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Nov. 19, 1946. 2,411,375 A‘ P. JACKEL REMOTE CONTROL SYS_TEM Filedv'July 31, 1943 4+ -wa Bc 8 Sheets-Sheet l a 6) I IN'VENTOR ‘ APL‘huPR Jac’kel. BYQQMMW H5’ ATTORNEY Nov. 19, 1946. 2,411,375 A. P. JACKEL REMOTE CONTROL SYSTEM Filed July 31, 1943 8 Sheets-Sheet v2 47 17 C’ B: i bl ‘bl 9 w: 1&1 lb: I5: ' 52 55 Office 4&1 i: 1? v 54,155 £56 49456" 1B. ‘ Apzflz - M INVENTOé unP. Jac'liel BYQQ H15’ I ATTORN‘I-LIY e2 Nov. 19, 1946. 2,411,375 A. P. JACKEL REMOTE CONTROL SYSTEM Filed July 31, 1943 8 Sheets—Sheet 4 J65‘ J47 115 F.“ J69 161 162 [60 115' 112 2A " Arz’bup ?viigiez . H15 BY ATTORNEY Nov. 19, 1946. 2,411,375 A. P. JACKEL REMOTE CONTROL SYSTEM Filed July 31, 1945 715 8 Sheets-Sheet 5 : 5 : 1 L5 ' lei id J01]Jim 0' 157 52 155 154 155 156 14945;; Fly'zg' maaillga H15’ ATTORNEY ’ Nov. 19, 1946. 2,411,375 A. P.IJACKEL REMOTE CONTROL SYSTEM Filed July 31, 1945 8 Sheets-Sheet? (459/1457 [60 y.” aH J. w 4 5 5H W .W@ We8_H0 /w R ._M9”? w ml.‘4 We 0 m .A0 a M» W r mA??? F .7Tpn F; -li.|m 52% \j p5 H um . mmm@a@ .31 +mp._ . RA. Rdw?w UY. r Nov. 19, 1946. 2,411,375 A. P. JACKEL REMOTE CONTROL SYSTEM Filed July 31, 1943 Sz‘afz'on Coding’ 153 Unit "is Sheets-Sheet 7 1/3», CM 5 S @2/ INVENTOR Apth up P. J¢Z0151Ql . Fly. 5 ._ BY a?wlll'we? H15’ ATTORNEY Patented Nov. 19, 1946 2,411,375 UNITED STATES PATENT OFFICE 2,411,375 REMOTE CONTROL SYSTEM Arthur P. Jackel, Penn Township, Allegheny County, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application July 31, 1943, Serial No. 496,907 16 Claims. 1 My invention relates to remote control systems, (Ci. 177-353) 2 of a series of register relays, one for each ele ment, as used heretofore. Another feature of my invention relates to im and more particularly to centralized traffic con trol systems for railroads comprising an oi?ce and a plurality of stations connected by line wires proved arrangements for associating additional over which impulse code signals are transmitted Cl station storage units with the same coding unit, to effect the operation of tra?ic governing de reducing the number of relays required when the vices located along the trackway, and to indi number of controlled devices at a location is cats the condition of such devices at the o?ice. larger than can be controlled and indicated by a The system of my invention is of the time code single composite code. A limited number of typaemploying codes of long and short elements 10 storage units may be connected directly to the which are transmitted one at a time over a single station coding unit, as heretofore, and in addi line circuit, and is based upon the system shown tion, auxiliary groups of selecting relays, desig in Letters Patent of the “ United States No. ‘ nated 1“pyramid” units, may be interposed to af 2,229,249, granted January 21, 1941, to L. V. Lewis, ford connections for additional storage units, for Remote control systems. My system includes 15 only one station coding unit being required at a also certain improvements upon the system of this patent relating to the use of a central bat tery line circuit of the bridged type ?rst shown in Letters Patent of ‘the United States, No. location even though the number of controlled devices is su?icient to absorb the entire capacity of the system. ' Another feature of my invention comprises the 2,303,875, granted December 1, 1942, to G. W. 20 provision of a starting relay of the normally ener Baughman and N. F. Agnew, for Remote control giz‘ed type in each station storage unit which ‘systems in order to permit the joint use of the takes the place of two relays as required hereto same line wires by the centralized traf?c control fore, and is also more e?‘lcient in operation. system and by other communication facilities. » 'Iviy invention as arranged for the indication of Certain features of my invention disclosed‘but train movements includes an improved “track OS not claimed herein, are claimed in my divisional storage” feature‘ for insuring the transmission of applications, Serial No. 554,199, ?led September an indication of a train movement through a 15, 1944, for Selective receiver for remote control particular track section even though the line cir systems, now Patent No. 2,381,499, issued August 7, 1945, and Serial No. 554,200, ?led September 30 cuit is not available when the train movement takes place. 15, 1944, for Transmitting apparatus for remote control systems, now Patent 2,393,377, issued Jan. 22, 1946. The system of my invention also includes nu merous circuit improvements whereby the timing of the relays which measure the lengths of the The components of the system of my invention code elements is more accurately controlled, as are preferably assembled in the form of coding will hereinafter be pointed out, thereby increas and storage units each containing a group of re ing the margin of reliability of the system, and lays. The system employs a station coding unit causing it to function properly through a wider at each ?eld location for transmitting indication range of variation of local battery voltage. codes and for selectively receiving control codes, together with a station storage unit for each unit > Another'feature of my invention relates to im proved arrangements for e?ecting joint opera group of controlled tra?ic governing devices, for associating such devices with the station coding tion over a line circuit which is used for the operation of telephone call selectors, without in unit. The of?ce equipment preferably includes terference. an individual control panel for each unit group of controlled tra?ic governing devices, and an 45 Another feature of my invention relates to pro o?ice coding unit which is connected over the visions at the office for preventing the further line circuit with the station coding units to es-_ reception of a code containing a manifest error, tablish communication selectively between each , such as might occur due to a fault when two sta panel and the corresponding station storage unit. tions attempt to transmit different code calls at One feature of my invention is the provision 50 the same time. a i 7 of an improved station storage unit requiring Other features, purposes and objects of my in fewer relays than heretofore, due to the provi vention will be pointed out as the description pro sion of a pair of register relays which are oper ceeds. ated alternately and repeatedly to register the ‘One form of apparatus embodying my inven character of a series of code elements, in place tion and several modi?cations thereof will now 2,411,375 then be pointed out in claims. 4 are transmitted by opening and closing the line circuit by operating relay OT periodically. The circuit also includes back contacts I) and d of a lockout relay X, provided in accordance with be described and the novel features thereof will _ Referring to the accompanying drawings, Figs. 1A, 1B and 1C, taken together, illustrate in con densed form oi?ce equipment employed in one for .’l of centralized tra?ic control system embody a feature of my invention, and in addition, the primary windings of an impulse transformer RT, inventionl The apparatus. :of FigsilA ‘ by means of which ‘the office line relay OR is controlled-when receiving indication codes, and comprises the'o?ice coding unit for gen the normally closed contact of a disconnect but and delivering control codes to the line and for receiving indication codes. Fig.1 10D ton DB by means of which the line may be opened ‘.r-nanually. Relay OR is of the stick polar type, 10 shows an individual panel containing :the as described and claimed in Patent N0. 2,303,875, levers and lamps for controlling and indicating a typical unit group of traf?c. governing devices ~~and>responds to impulses of alternately opposite "polarity delivered by transformer RT when the in the ?eld, together with the ‘selecting relays for associating the one‘ panel‘ with"v the of?ce 15' lineicurrentis varied by the operation of a sta tion transmitter relay T, such as' is shown in coding unit. It is to be understood that each 2A.! Indication codes are transmitted by panel is similarly connected but by‘means of operating relay T to connect the line wires to a different arrangement of selecting relays. gether periodically through an impedance of Figs. 2A, 2B and 2C, taken together,’ illustrate the corresponding apparatus at a typical ?eld 20 relatively low value iii-comparison with the nor ing my and 1B‘ erating circuit, . mal impedance of the line circuit, comprising ‘location arranged as required-"when there is but one unit group of controlled devices at the loca tion. The apparatus of Figs; 2A'andi2B, together - with the left-hand portion of Fig. 20, comprises I the station coding unit, while the right-hand por the coils of alow pass ?lter LPF'similar to the vrone at the ‘office, which is interposed ‘between the-line and the station apparatus. 25 tion ‘of Fig. 2C shows the relays of a station storage unit suitable for the ‘control of a typical " At each ?eld station, as shown in Fig. 2A, 2. ~ high resistance line relay R is connected across the line wires Y. and Z in series with a resistor WI, the connection normally including back con ‘groupof 'traflic governing devices. Fig. 20 also tacts band d of a master relay M and the coils ‘includes a .track‘diagram ‘illustrating such a . group,‘ which as showmincludes a power oper-x 30 of the low pass ?lter LPF. The station line re ~ated track switch and a group of signals such ' ' lays Rare of the biased polar type and are nor ‘mally energized, in parallel, by current supplied ' as: are commonly associated'with one-end of a by battery 8%, each relayR closing its left-hand passing siding on a ‘single track railway. It is ‘to be understoodth‘at‘the portion of the coding contacts a and b, as shown, when its left-hand, ‘ unit‘ shown in'Fig. 2C is arranged to provide con-l. 35 terminal is positive, and closing its right-hand ‘contacts a and bwhen energized. in the reverse nections‘ for from one to ?ve station storage ‘units, such as the one‘shown. direction. with its right-hand terminal. positive, . or when-deenergized. The connection of the sta tion apparatus to the line wires‘ Y and Z'is con trolled by a fault relay RPP in a mannerherein Fig. 3 illustrates the circuits for the pyramid ‘units hereinbefore referred .to, and replaces the left-hand portion “of Fig. 2G in the circuit plans; when connections for additional storage units are after pointed out, but as this relay is not involved ' ' in the normal operation of the system itmay be required. v .. assumed for the present to remain inits normal Fig. 41 illustrates amodi?-cation of a portion energized position as shown. ' of the oii’lce coding unit which replaces the upper ~ ‘part of‘Fig. 1A in the circuit plans when thersysa ‘ . I Each station line relay R. controls a group of slow release timing relays Ll, L2, LP, LB and ~tem isto use aline circuit over. which telephone selectors are controlled, this View also-showing a typicalcodewheel and apparatus for trans »mitting selector code calls. LBP. These timing relays are normally deener gized and are controlled by relay R to govern the ! transmission and reception of codes in accordance Fig. 5 illustrates another modi?cation of 7 av 50 with line conditions like the similarly designated relays of‘ Patent No. 2,229,249, hereinbefore re portion of the of?cecoding unit of Fig. 1A, .com “prising, a. circuit. for. controlling . a secondary v ferred to. Their release times are likewise gov erned by electronic recti?ers, as shown, the rec ti?ers also ‘serving to prevent contact sparking in the line, ortc meet other special line condi-;. ; - ‘and to minimize contact wear, as explained in " this'patent. tions. The system. of my invention is arranged to Similar reference characters refer to similar ‘employ codes each having sixteen steps, and in parts in each of the ‘several views. each control code delivered by the o?ice trans Referring to Fig. 1A, the reference characters Y and Z designate a pair of line wires which 60 mitter relay OT, the line circuit is open during ‘each odd-numbered'step and closed during-‘each extend from the o?ice through the several sta . even-numbered step. More particularly, thefoii‘ice tions and provide a line circuit for the centralized ' coding unit is placed in condition. to transmit a traf?c control system of my invention and also control code by energizing the master relay OM may be used to provide channels for telephone transmitter relay TS which may be used when the control of?ce is locatedat an intermediate point and telegraph communication, as explained ini 65 of Fig. 1A, which completes circuits for eifecting the periodic operation of the associated trans connection with the similarly designated line ' wires shown in the Baughman et al. Patent No. “ mitter relay OT to open and close the line circuit to‘ operate the line relays R at all stations in 2,303,875. This line circuit, as shown, is nor unison, both the open and closed periods constit "mally energized by current from the office line battery as, the positive terminal of‘ which‘is” 70 ‘tuting code elements. When the line circuit is opened to ‘begin the normally connected to line'wire Y and the nega "first element of a code, each line relay Rreleases tive terminal to line wire Z over back contacts "and its right-handrcontact b completes a circuit I) and d of a pole changer relay PC and of the from the-positive or sup-ply terminal B of a suit "office transmitter relay ‘OT and the coils of a suitable low pass ?lter LPF, and control codes" able local source of current over aback contact 2,411,375 5 6 d of relay I6,;back contact a of relay L2, back charging current as is desirable when the line is in a cable. At the same time, relay OT operates contact g of relay LBP through relay LI to» the negative or common return terminalC of the source. Relay LI then picks up and its front con tact a completes a circuit from terminal B at the relay OR to reverse over the circuit extending from the positive terminal B over front contact e of relay OT through relay OR to terminal 0. right-hand contact I) of relay R through relay Each time relay OT releases it closes the line circuit to pick up the line relays R and at the same time it operates relay OR to normal 'by com pleting a stick circuit at its own front contact a pleting the circuit at its back contact e extending and also completing a circuit from terminal B over front contacts 0 of relays L! and L2 to pick 10 from terminal 0- through relay OR to terminal C. Relay OR thus operates in unison with the relays up relay LP, which relay in turn completes cir L2 to terminal C, so that relay L2 picks up, com R during the transmission of control codes. Each line relay controls a chain of counting relays over circuits generally similar to those of cuits over its front contact a to pick up relays LB and LBP. Relay LBP becomes energized in tandem with relay LB when the latter closes its cessively after relay LP is released. When relay L2 picks up on the first step of a code, its contacts Thus relay OR, by means of its contact a, controls the counting relays OI to O8 and 018 of Fig, 1B, and each relay R con a and 9 shift .theccnnections of relay LI from trols a similar chain such as the relays I to 8 front contact a so that these relays release suc 15 Patent No. 2,229,249. and I6 of Fig. 23. Referring to Figs. 2A and 2B, it will be seen that a pick-up circuit for relay 5 R, and then contact g of relay LBP is picked up is closed momentarily in response to the first of a to maintain the latter connection until the code series of operations of relay R, which extends is terminated. It follows that relays Li and L2 from terminal B at the right-hand contact a of are energized alternately, relay LI over the left relay R over back contact e of relay I6, back con~ hand contact I) of relay R, and relay L2 over the right~hand contact 2) of relay R, in response to 25 tact b of relay LBP, front contact g of relay Ll, wire IBI through relay I to terminal C. Relay I the periodic operation of relay R. Relays LI and therefore picks up on the ?rst step of‘ a code L2 remain picked up for the duration of short the right-hand to the left-hand contact I; of relay code elements, relay LI releasing during each odd-numbered long element and relay L2 during each even-numbered long element. These relays serve, therefore, to indicate code character in a received code, and together with relay LP they serve to control the lengths of the long steps of a code generated by the associated transmitter relay ‘T. Relay LB and its repeater relay LBP *' are bridging relays which remain picked up for upon the energization of relay LI, and when relay LBP picks‘up, it opens the circuit just traced and closes a stick circuit for relay I extending over front contact 17 of relay LBP, wire H9, back contact b of relay 2, front contact a and winding of relay 5 to terminal C. When relay R is op erated to normal to begin the second step of a code, terminal 13 is disconnected from relay. I, which remains picked up due to the discharge the duration of a code and serve to prepare var path provided by the recti?er connected to wire ious local circuits when the code operation of relay R begins and to open them when it ceases. The oliice line relay OR, Fig. 1A, controls a H2, and a circuit is closed from the left-hand contact a of relay R over front contact at of relay similar group of timing relays OLI, 0L2, OLP, OLB and OLBP, which function in a similar man LBP, wire £28, back contact a of relay 8, front contact I) of relay I through relay 2 to terminal C. Relay 2 therefore picks up and completes its stick circuit extending to terminal B at Wire I20 ner. Relay 0R, however, is normally deenergized over its front contact a and back contact b of and is adapted to hold its contacts in either posi tion to‘which it is operated by a momentary im 45 relay 3. The operation of contact I) of relay 2 disconnects relay I from the rectifier but closes pulse, and hence it may become accidentally a second discharge path for relay I comprising reversed. 'If this ‘occurs, relay OR is restored automatically to normal by the action of the timing relays in a manner hereinafter explained, and it may be assumed therefore that relay OR, although deenergized, occupies its normal posi tion corresponding to that of the normally ener gized station line relays R, when the system is the winding of relay 3, whereby relay I releases shortly after relay 2 picks up but without spark ing at its contact a, the dropping of which con» nects relay 3 to wire H9 to condition that relay to respond to the third step of the code. Relays A to it are similarly controlled one at a time by current supplied alternately over wires H9 and When receiving indication codes, relay OR is 55 I20 in response to the fourth to ‘eighth steps of the code. If the various operations associated operated by impulses of alternately opposite with these steps as hereinafter described are polarity delivered by transformer RT. During properly carried out. a chain repeat relay CR is the transmission of control codes the master relay picked up on the eighth step to prepare a pickup OM, Fig. 1A, is held energized and its contact 0 circuit for relay I over front contact I) of relay short circuits transformer RT and disconnects 8 so that relay I will operate as the next in order it from relay OR, and relay OR is then operated after relay 8, relays I to ‘I being then operated locally by the transmitter relay OT. When relay through a second cycle on the ninth to ?fteenth OM picks up, relay OR becomes energized in the .teps of the code, relay i6 responding in place normal direction, as shown, over the circuit from the mid point terminal 0 of the local battery 65 of relay 8 on the sixteenth step, during which the apparatus is restored to its normal at rest through its lower winding, back contact 6 of relay in its normal at rest condition. ‘ OT and front contact 6 of relay. OM to the nega condition. tive terminal C. From a comparison of these circuits with those of Patent No. 2,229,249, itwill be seen that a Relay OT becomes energized over contact at of relay OM and is then controlled over wires 68, Stand 62 in a manner hereinafter explained to generate the code. Each time relay 0T picks up, it opens the line circuit at its con tacts b, and d to release the line relays R at the stations and connects line wire Y to wire Z > discharge path is provided for each of the relays I to 8 each including the winding of another re~ lay, which paths are effective on each interme diate step of the code, whereas in the patent'they are effective on certain steps‘ and not on others. through a resistor W5 to discharge the line 75 It ‘follows that the circuits asshown herein pro 2,411,375 7 vide more uniform. and accurate operation of the counting relays in receiving a code, and since these relays control the transmitter relay T, the 8. stepto distinguish it froman indication code in which the ?rst step is relatively ‘short. ‘ When relay‘ OI picks up on the ?rst step,vits transmitted impulses are made-more uniform. back contact .17 opens the pulsing circuit for relay Referring now to Figs. 1A and 13, it will be 5 OT, but relay OT is held energized to generate a seen that the o?ice counting chain circuits are long step over a branch circuit extending from similar to those above described, relay Ol picking up on the ?rst step over wire 8!, the remaining relays being operated one at a time by current terminal B at front contact 0 of relay OI, back contact 01 of relay SP, contact e of relay OLI and contact I) of relay OLP in parallel, back contact supplied alternately over wires !9 and 2%) in re IO e of relay SP to wire 68, and'thence over contact sponse to the periodic operation of relay OR. ‘ 01 of relay OM and the winding and front con In Patent No. 2,229,249, the timing relays Li tact c of relay OT through resistor W3 to termi and L2 and the counting relays are energized in nal c. Relays OLI and OLP then release suc parallel over the same contacts of the line relay, cessively, the opening of contact I) of relay OLP in which case the release periods of the timing disconnecting terminal B from wire 68 causing relays depends to some extent on whether or not relay OT to release to energize the line relays R a counting relay is connected in parallel there and to operate relay OR to the left to begin the with to provide a discharge path for a portion of - second step, relay OR causing relay O2 to pick its stored energy. This is a variable condition up and relay OI to release. in the normal operation of the system, as herein 20' The closing of back contact g of relay Ol com‘ after pointed out, and the provision of separate pletes the pulsing circuit for relay OT over wire contacts a and b for the line relays R and OR 63, this circuit functioning repeatedly to gener renders the operation of the timing relays more ate the short steps of the code. The pick-up uniform and accurate. time of relay OT depends upon the time constant I shall now describe the transmission of a con trol code, step by step, by the oi?ce apparatus of Figs. 1A, 1B and 1C. To initiate a control code, ‘the operator momen tarily presses a starting button STB identifying the control panel ‘associated. with the station storage unit to which the code is to be trans mitted to thereby pick up a starting relay such as the relay ZMST, which relay is held encr gized over a stick circuit extending to terminal 13 at the back contact 2' of an associated panel selector relay such as the relay 2343 until the desired selection has been eifected. Wire 4?, in Fig. 1C, is normally connected over back contacts of various selecting relays E, F and G to branched ' circuits extending to contact b of the starting ‘ relay ST of each panel. The closing of front con .tact b of relay 234ST'therefore extends the con nection of terminal B over a particular branch, which as shown, includes back contact a‘ of relay 234s, and back contacts 9 of relays 23G, 2F and E to wire 41, and if the system is in its normal at rest condition so that relays OLI and 0L2 are released, a circuit is completed from terminal I B at wire 41 over the back contacts b of relays 0L! and 0L2 through relay OM to wire I? and then. to terminal C at the normally closed con tact of the cancelling button CB. Relay OM therefore picks up in response to the operation of any startingirelay such as ZMST and completes a pulsing circuit for the o?ice transmitter relay OT extending from terminal B at back contact e of relay Ole over back contacts a of relays O1, O5, O3 and 0!, wire 68, contact d of relay OM through relay OT and. resistors W2 and W3 to terminal C. Relay OT therefore picks up to be gin the ?rst step of the code, its front contacts b and d opening the line circuit to release the station line relays and its front contact e com pleting a circuit already traced for operating re lay OR to its reverse position, whereupon relay OR operates the timing relays 0L and the ?rst counting relay‘ OI as already described. When relay OLB picks up, its‘contact c completes a stick, circuit for relay OM extending from ter minal B at back contact 2 of relay OlS, wire I8, contacts 0 of relays OLB and OLBP, in parallel, contact a and winding of relay OM, and thence over wire I’! to terminal 0. The ?rst step of each control code is a long 75 7 of the circuit including its winding and resistors ' W2 and W3. ' When relay OT picks up, its front contact 0 short circuits resistor W2 so that the energization of relay OT rises‘ quickly to a higher value than would otherwise be the case, and con sequently providing a more constant release peri od under conditions of variable voltage. Its re lease period, it will be noted, is determined by 1e time constant of the circuit including its winding and resistor W3 only, and it follows that its pick~up andrelease periods may be adjusted independently. Wires 6| and 62 provide connections, described hereinafter in detail, for holding relay OT picked ’ 7 up or released to generate the long steps of the code‘. The connection-from terminal B to wire M is controlled by relays OLI and OLP so as to hold relay OT picked up after its pulsing cir cuit opens, to generate a, long odd-numbered step, while a similar connection controlled by relays . 0L2 and OLP extending from terminal B over wire 62 and front contact f of relay OM and back contact 0 of relay OT to the left-hand ter minal of relay OT is effective to short circuit its winding and thereby hold relay OT released after its pulsing circuit closes, to generate along even-numbered step. ' The second to eighth steps of each code may be arranged in any one of thirty-?ve different combinations of three long and four short steps to form station code calls, which are identi?ed by three-digit numbers in which the digits rep resent the long steps of‘ the code call. Thus the number 235, assigned to the individual panel of Fig; 1C and the corresponding station‘ storage unit of Fig. 2C, is one in which the second, third and fourth steps of the code are long, ‘and the ?fth to eighth steps are short. The code calls are generated by completing connections from‘ terminal B at contacts b of the office starting relays ST, to wires 6! and 62, these being ar ranged so that when a plurality'of starting relays are energized, their respective codes will be trans mitted one at a time in a‘ given order of code superiority, a long element taking precedence over a short one on each step._ That is to say, 234 is the most superior code call, 235 the next, and so on, 678 beingthe most inferior. The se lection of the of?ce panel containing an ener gized relay ST is effected by the energization of an entry relay E, Fig.- 1C, in response to the ?rst 2,411,375 element of the code, followed by the energization of three relays in sequence by the three long ele ments of the code call, comprising a ?rst selector relay F, a group selector relay G, and a station 10 cuits for generating code calls in which the ?rst digit is 3, 4, 5 or 6. Each of the relays E, F and G, and certain other relays hereinafter described, are provided with selector relay S, these relays being identi?ed more a discharge circuit including a resistor in lieu. of particularly by pre?xes designating the code ele the usual recti?er. These resistors are of a rela ments by which their operation is effected. For tively high value in comparison with the resistance example, relay 2F is responsive to the second ele of the relay winding, and provide a slight degree ment, relay 23G to the third, provided relay 2F of retardation in accordance with the circuit re has been operated, and relay 234s to the fourth, 10 quirements, and also serve to prevent contact provided relay 23G has been operated. When sparking. used to capacity the system will employ ?ve F When relay 03 picks up, the connection from relays, ?fteen G relays and 35 S relays, arranged terminal B over wire 33 is extended over contact generally as shown in Figs. 2, 3 and 4 of Patent 0 of relay O3 and back contact e of relay OCR to No. 2,229,249 and since the relation of these re wire 5! to complete the stick circuit for relay O'I‘ lays one to another and the connections for as to generate the long third step of the code call sociating the different panels with the coding 234. unit may be ascertained from the patent, for sim plicity I have shown the circuits hereinv in con a circuit from terminal B at wire Bil over back densed form, showing the circuits in detail for only one panel and for only one selecting relay of each kind. Relay E is picked up on the first step of each code, over a circuit extending from terminal B at Relays OLI and OLP release, completing contact a of relay OCR, wire 53, back contact (2 of relays OLP and OLI to wire 63, back contacts b of relays OCR and OCD, front contact (1 of relay 03, wire 23, front contact I) of relay 2F through relay 23G to terminal C. Relay 23G picks up, its contact a completing a stick circuit extending over contact a of relay OLBP, Fig. 1A, wire 60, back 25 back contacts a of the associated G relays in se contact a of relay SP, front contact d of relay OI, ries to wire 29, and thence to terminal B at wire Wire 2|, ‘through relay E to terminal C, and relay 60. E then completes a stick circuit at its front con When relay 23G picks up, the branch circuits tact at extending over back contact m of relay 2F, extending from wire 33 to terminal B over the and over back contacts of relays 3F to BF, if pro 30 contacts of those starting relays which have 23 vided, to wire 29, and thence over resistor W4, as the ?rst two digits of their code calls are dis back contact a of relay SP and wire 60 to terminal connected from Wire 33 and divided into branches B at contact a of relay OLBP, by contacts 9 to k of relay 2G and connected to It is to be understood that each of the branch wires 34 to 33 to prepare circuits for'gcnerating circuits extending from terminal B at contact b the third digit of the calls 234 to 238, respectively. of a starting relay‘ST to wire 41 identi?es the cor responding code call, as indicated by the refer ences 234 to 238, adjacent contacts g to k of relay 23G. When relay E picks up, these branches are all disconnected from wire 131 and divided into groups by contacts 9 to lb of relay E, and con nected to wires 32 to 36 to prepare circuits for generating the ?rst digit of the code call. When relay 02 picks up on the second step, the connection from terminal B to wire 32 is ex tended over contact 0 of relay 02, back contact J‘ of relay OCR to wire 62, and thence to the left hand terminal of relay OT, thereby short circuit ing its winding and holding relay OT released to generate a, long second step. Relays 0L2 and OLP release, completing a circuit from terminal B at wire 60 over back contact a of relay OCR, wire 58, back contacts d of relays 0L2 and OLP, wire 64, back contacts d of relays OCR and OCD, front contact d of relay 02, wire 22, front contact 17 of relay E through relay 2F to terminal C. Relay 2F picks up, its contact a completing its stick circuit extending over back contacts a of relay 23G and The interruption of the connection to wire 63 by the opening of back contact g of relay 23G allows relay OT to release to begin the fourth step. Relay 2F is released by the opening of back conv 40 tact a of relay 23G, and the opening of front con tacts h to k of relay 2F disconnects the branch circuits which these contacts control, thereby limiting the control‘ of the third digit to those starting relays of the group 235 to 238. 45 When relay 04 picks up, the connection from terminal B over wire 34 is extended'over contact 0 of relay O4 and back contact f of relay OCR and wire 62 to hold relay OT released to gen erate the long fourth step of the code call 234. 50 Relays 0L2 and OLP release, completing a circuit from terminal B at wire 66 over back contact a of relay OCR, wire 58, back contacts (1 of relays OLP and 0L2, wire 64, back contacts at of relays OCR and OCD, front contact if of relay 04, wire 55 24, contact b of relay 23G through relay 23% to terminal‘C. Relay 234s picks up and the closing of its front contact a extends the connection from terminal B at its left-hand terminal, to wire 33 and thence through relay SP to terminal C, so of other G relays of the same group, such as the relays 24G to 21G, if provided, to wire 29, and 60 that relay SP picks up, completing its stick circuit extending from terminal B over wire 6% and its thence to terminal B over wire 6%]. front contact a and winding to terminal C, and When relay 2F picks up, the branch circuits ex also completing a stick circuit for relay 2315s ex tending from wire 32 to terminal B over the con tending from terminal B at the front‘ contact a of tacts of those starting relays which have 2 as the relay SP, wire Siland the front contact a and ?rst digit of their code calls are disconnected from winding of relay 234$ toterminal C. i wire 32 and divided into groups/by contacts 9 to k The interruption of the connection to wire ‘62 of relay 2F and connected to Wires 33‘to 31 to pre by the opening of back contact 51'" of relay 2343 pare circuits for generating the second digit of allows relay OT to pick up to begin the fourth the code call. The interruption of the connec . tion to wire 62 by the opening of back contact 9 70 step. of relay 2F allows relay OT to pick up to begin It'will be seen, therefore, that whereas at the the third step. Relay E is released by the opening of back con tact m of relay 2F, and the opening of- front con tacts h to k of relay E disconnects the branch cir end of the ?rst long step, relay CT is operated ‘by opening a front contact of relay LP, in the case of the long steps of the station code call 75 relay OT is operated by the opening of back con 2,411,375‘ 12 tacts of the selecting relays .215‘, 23G and 234s, tiontof the associatedstarting button 'S'I‘B to respectively, each of which relays picks up in re sponse to' the closing of a back contact of relay LP. It followsthat the long steps of the station the“ button is operated before'zthea?rst' code. is. code can are all-of-the same length, but these are slightly longer than the other long stepsof Duringthe. reception of an ‘indication'code, relay O?‘and' the relay S of the selected panel: are the;code';.which 'are terminated in the same man also energized as in the case of the control code store ~ 9. second code‘ for transmission;v even though -1 completed; described, but then=receivingrelay OM is‘ not energized‘iand its‘ backicontact 9 provides a con When": relay S3v picks up, the opening of its. back "contact a disconnects terminal B from wire 10 nection from terminal '3 to wire 46 to preventthe nerrasthelong ?rst step. 29, thereby releasing relay 23G. The opening of release of the starting relay, such ‘as relay ‘23’4ST, , in response ‘to the‘ operation of:relay.-OB;v the front contacts I)‘ to f of relay 23G opens the When relay 0 l E picks-up on-the sixteenth step,.. pick-up circuits for relay 234s and other similar which, being duezto thee release'of :r'elay OT; is a 1 relays 2353 to 2388, not shown, of the same group, while the. opening of front contacts h to k of 15 line closed step, termina'lBiis‘disconnected from. relay 23G prevents the generation of long code wires 68. and H3 at back contact‘ 6 of reIayVO'IB - elements on the ?fth to eighth steps, when con slightly‘ before relay .Olrreleases to‘;close itsi backv contact ,g.. Consequently‘. relay OT ‘remains re‘ wires. 35 to 38- are successively closed. leased, relay OR remains normal; and ‘relay OM-' The fifth to eighth steps are therefore short, 20 jreleases, andxth'enthe timing'irelays, OLaZ, .OLP, and :when relay 08 picks up a circuit is completed OIiB; OliBP'and‘ OLI release in that orderx Relay/J 066, which is held energized over a stick circuit? from terminal B over Wire BiLcontact h of relay including wire 481'and contact b of relay OLB be O8,;contact b of relay SP, through'relay OCR to . tacts e of the counting relays O5 to 08 leading. to terminal C." Relay OCR therefore picks up on the " comes deenergized upon the release of relay OLB ‘ eighth step completing a stick .circuit at its front 25 and releases. Relay 'OLBPYY disconnects terminal-vi B from wire 68, thereby releasing relays CR,'1SP I‘ contact .a, The opening of back contact a of andthe operated selector relayv such as. 2312s,: relay OCR disconnects terminal B from Wire 58 whereupon .the apparatus is in conditionsto .re-./ and hence from wires es and t4, and the closing ceive a new code. If any other office starting relay of front contact 9 of relay OCR prepares a circuit extending from wire I9 over backcontact b of 30. has been picked up ,to storea .controlfcode‘, such 1, codewill be initiated upon, the release of‘relay ' relay RCR, back contact a of relay 0'! and front contact b of relay 08 through relay O! to termi OLai , this relay being the lastto release. The six-. teenth step thus corresponds to the return of the‘ ~ nal C,‘ to allow relay 0! to be operated as‘ the next in order‘after relay 03. line circuit to its normal closed condition, and .in.~case of the transmissionpf. successive codes, Steps 9 to 15 of the code have now been ren represents a line closed ‘step which is materially dered available for the control of seven movable longer than any .suchistep occurring within a » devices at the selected. stations, in accordance with the positions of the control levers or push code; Consirlering now the operation. of ‘the station buttons of-the corresponding panel, such as the apparatusof Figs: 2A, >2B1and‘2C‘in receiving a » one shown in Fig.'lC. VWhen relay 234$ picks control code‘ just described, it will be‘under-J up, terminal B becomes connected over its con tacts d to h' to the lever contacts and thence to v the wires 39 to‘ 45 leading to contacts 1‘ of relays O1 to 07. With‘relay OCR‘ picked up, the f ‘ contacts of the-r-odd-numbered counting ‘relays provide connections over front contact 11 of relay SP,¥front contacts e and b'ofrelays Old and ‘ OLPJin parallel, front contact e of relay OCR to ' wire 6|v and thence to the stick circuit for relay‘ . ' O-T, whereby relay. OT may be held energized untilvrelays OLl and. OLP release, to thereby generate long odd-numbered code elements. The f contacts of the even-numbered counting relays stood that the line ‘relay R at each vstationv and ~ . the timing reEays'Li, L2, LP," LB and LBP operate 1. in'unison with the corresponding .ofiice relays. The counting relays at .each station operate through the first eight steps'in’unison. with they o?c‘e :ccunting relays, while only those at the. selectedqstation atwhich :the selector'relay S‘ is‘ picked ‘up,:*are operated through their second . I'cycle; Onthe first step ;of_~the; control code a delivery ‘control relay 'CD'is selectivelyioperated:‘ inv long response character to' the‘release of _this"step,'.over ofv relay ‘Ll, a circuit; clueyto the eX-w provide connections over front contacts 0 of re tending from terminaLB at frontv contact CV01}: lays 0L2 and OLP in parallel, and front contact 1‘ of relay OCR to wire 62, and thence to the left :relay‘LBP, wire i?il, ‘back-contact d of "relay<Ll_,:1 hand‘ terminal oflrelay OT, whereby relay OT. may be vheld-released until relays 0L2 and OLP - wire £693, fbaokv'contact b of relay CR,~conta‘ct c" of relay -i, through the "upper winding of relay," CD'to terminal ‘C.- Relay‘. CD picks up and ‘com-‘ pletes a stick circuit from terminal Blat-jwire I601,‘ release, to thereby generate long even-numberedv code'~ elements, these .circuits obviously being 60'". over its contact a and~lower=winding~ to termia Y nal C. v , available only‘during~~'the second cycle of opera As shown in Fig 2C; the-station- coding unit tion of the counting relays. In View of the simi larity of these control circuits to those‘ of Patent No. 2,229,249, a detailed description in the present contains a set of ‘three selector- relays ‘FA, GA’ described,;its' contact’i transfers the direct con nection of'terminal- B tothe stick circuit for the relay ‘8 is responsive ;to_ ther~code ‘call 234»- The circuits‘for these relays aregenerally- similar to thosefor the o?ice selecting‘relays alreadyde iscribedp The-circuits- for the selector relays/which ‘ and vS,.;'~.vhiclr1- may be‘ adju‘sta'bly ‘connected-to 651 respond to anyone ofthe'thirty-?ve'code calls, application is believed to ‘be unnecessary. the connections asshown -.being*arranged~so; that- When the selector relay 234$ picks up as above‘ starting relay 234ST to one including wire 46 and - extending to terminal B at back contact f of relay O8,~>and it follows: that the operated starting relay. such'as-i 23481’ is released‘ on~the eighth step‘of the corresponding code. This'has the ad_ vantage‘ that it permits the starting relay of. any paneltO-be ‘reenergizedby a momentary opera-v respond terminal- on B ateven-numbered front contact a‘ steps of relay-LBPgFig. .- extend" from“ . 2A, over wire let/back contact at of relay L2, wire ltd, ‘back’ contact-d of relay CR,ifront contact 4d j ‘.‘of relay CD'and thence;over'frontycontacts d of: 2,411,375 13 relays 2, 4, 6 and 8 to wires I22, I24, I26 and I28. As shown, a connection to wire I22 provides a 'circuit for energizing relay FA on the second step, relay FA having a stick circuit extending to ter minal B at wire I66 over its own front contact a and a back contact "/22 of relay GA. The circuits for the selector relays which respond on odd- , 14 stick relays, such as the relays FS and MCS shown. These polar stick relays are operated to normal . or reverse by impulses supplied by the coding unit over wires I49 to I55, inclusive, and are placed under the control of the station coding unit by the operation of a delivery relay D. Re lay D at the selected station is picked up when relay 8 releases on the ninth step of a control numbered steps extend from terminal B at wire I60 over back contact (1 of relay LI, wire I53, back contact 21 of relay CR, front contact I] of relay 101 code, over a circuit extending from terminal B CD, and thence over front contacts cl of relays at contact 0 of relay CR, Fig. 23, back contact e 3, 5 and ‘I to wires I23, I25 and IN. As shown, of relay 8, front contact 0 of relay CD, wire H5, a connection to wire I23 provides a circuit over front contact g of relay S through relay D to contact I) of relay FA for energizing relay GA, the terminal C, and remains energized until the end stick circuit for which extends to terminal B‘ at 15 of the code. wire I60 over its own front contact a, and back Circuits suitable for operating the polar stick contact a of relay S. Similarly, a connection to control relays in accordance with the long .or wire I24 provides a circuit over contact b of relay short character of the ninth to ?fteenth steps of GA for energizing relay S, the stick circuit for the code are obtained by the operation of a pair which is connected directly to terminal B at wire 20 of register relays PI and P2, Fig. 2A, the circuits ‘ see over its own front contact a. for which are prepared by the closing of front It is to be noted that the various selecting re contacts of relays CR and CD. If relay LI re. lays G and S are operated directly following leases on any odd-numbered step of the group the release of relay LI or L2 when the apparatus comprising steps 9 to I5, a circuit is closed from is in the receiving condition as described, and 25 terminal B at contact a of relay L'BP, wire I60, consequently these relays are operated prior to back contact (1 of relay LI, wire I 63, front con the termination of the long steps, thereby pro tact b of relay CR, front contact h of relay CD, viding a margin to allow for variations in timing. wire I29, and the upper winding of relay PI to It is to be understood that the relays FA at the terminal C. When relay PI picks up, it is held different locations may be connected to any of 30. energized for the duration of the next following even-numbered step over a stick circuit extend the wires I22 to I26, and the relays GA to any ing from terminal B at the left-hand contact a of the wires I23 to I21 below the one to which of relay R, front contact 01 of relay LBP and the the associated relay FA is connected. It follows front contact a and lower winding of relay PI that when the code call is 234, those relays FA ' to terminal C, relay PI releasing when the left connected to wire I22 will respond to the second hand contact a of relay R is opened at the be long step, those relays FA and GA connected to ginning of the next odd-numbered step. Simi wire I23 will respond to the third long step and larly, if relay L2 releases on any one of the even those relays FA and GA connected to wire I24 numbered steps III, I2 or I4, relay P2 is ener will respond to the fourth long step along with relay s of the selected station storage unit, but 40. gized over the circuit from terminal B at wire I60, back contact 01 of relay L2, wire I64, front that the selection will be completed to pick up contact (1 of relay CR, contact a‘ of relay CD, wire a relay S at one location only. At theiother I19 and the upper winding of relay P2 to termi locations the counting relay operations terminate nal C. When relay P2 picks up, it is held ener-‘ with the eighth step and only the line relay R and the timing relays continue in operation 4. gized for the duration of the next odd-numbered step, during which relay R is reversed, over a through the remainder of the code. stick circuit extending from terminal B at the At the selected station, relay S prepares a pick— right-hand contact a of relay R, back contact e up circuit for relay CR completed on the eighth of relay I 6, front contact b of relay LB? and step. 7 This circuit extends from terminal B at the front contact and lower winding of relay P2 50 contact :1 of relay S, Fig. 2C, wire I46, contact 1‘ to terminal C, relay P2 releasing when the right of relay 8, relay CR. to terminal C, and when relay hand contact a Of relay R is opened at the be CR picks up, its front contact a completes its stick circuit extending to terminal B over wire I60. ginning of the next‘odd-numbered step. ‘ The circuits which the contacts of relays PI Front contact g of relay CR. completes a connec and P2 provide for the control of the polar stick tion from wire I I9 over back contact a of relay 1 55 relays are of a variety of types, one of which is and front contact b of relay 8 for effecting the operation of relay I next in order after relay 8, and front contact 72 of relay CR completes a con nection over back contact g of relay 8 for ener gizing relay It‘ in place of relay 8, on the six teenth step. The ninth to ?fteenth steps of the control code are employed for the control of a series of con trol relays of the stick polar type, in accordance with the positions of the corresponding o?ice levers. Fig. 20 shows a typical arrangement of such relays including a switch control relay WS and signal control relays LI-IS, RHS and COS, illustrated bythe circuits for relay WS, which relay is controlled in accordance with the posi tion of the switch lever SW of Fig. 10. When lever SW is normal, the ninth step of the control Code is long and the eleventh step short, and when lever SW is reversed, the ninth step is short and the eleventh step long. If lever SW is nor Vmal, relay PI is picked up‘ on the ninth step, and When relay R is operated to the left to begin the tenth step, its contact a connects terminal B to the stick circuit for relay PI to hold it picked up, and also connects terminal B to front contact b of relay PI to complete a circuit momentarily which may be used to control a track switch and 70 over wire III, contact e of relay I, wire I49, con an associated group of signals in the manner tact a of relay D through the upper winding of described in connection with Figs. 8 and 9 of relay WS and the front contact of relay LR to Patent No, 2,229,249. In the present system, terminal C, thereby operating the contacts of however, the control code includes two additional ‘7 relay WS to their left-hand position as shown. steps providingfor the control of two additional Relay WS is thus energized in the normal direc 2,411,375 f‘: tion in multiple with relay 2, by animpulse which. is terminated upon the release of relay 1 . Relay. PI is not operated“ on: the. eleventh step, and release ‘ in unison‘ with :the corresponding;.oflicerr relays'and' likewise the-relays .1, ‘it; CR and‘ S :at ' although, v.at the beginning-of ‘the. twelfth step, the‘ selected station,.relay. Li. beingthevlast vto: ' release. Relay CD is released by relay LBP along . wire" III is connected momentarily over contact . With relay CR and then'relay D is released, plac e of relay 3,‘wire I51‘, contact c of‘ relayDand the lower ‘winding ‘of relay WS toterminal C; ing the apparatus in‘ condition to receive a newv code. The release ofLrelay. Ll. places the appa-. ratusin condition .ito initiate the transmission of relay WS'is not energized because relay Pi is. in an indication "code; iassuniingthat the relay 'SS, its released position in'whichlwire'l H‘ is discon; nected‘ fromterminal‘B; Similarly,"if lever SW 10 hereinafter describedgis: not -.energizecl. The. station:codingrapparatus of Figs. 2A, 2B is reversed, so that the ninth step is short, relay Pl remains released and relay .WSis not oper and.:2C'. is also adapted to transmitindication codes whichthe. of?cezapparatus is adapted to ated on‘vthe itenth: step, 4 and. when the. long‘ elev enth step is. reached irelay Pl‘ipicks up'so that receive. Each indication code‘ comprises sixteen relay WS‘ receives an impulse throughiits lower 15 steps, of which the? ?rstlis relatively short, the second to eighthiarezarranged inzdiflerent com Winding to. operate .it to reverse on the twelfth step. binations of threeilo-ng.=-and four. short steps to operate selecting .relays'F, ‘G and S at the office ~ Another'typ‘e of 'contr‘olcir'cuit-is illustrated by the one" forlrelayiFS; which is ‘controlled by the and station in‘ accordance with different code o?ice Ikey 'FTB so as to be operated .to normal or 20 calls as alreadyv described, and in which. theninth to ?fteenth steps mayl'belmade long or short to reverse in accordance lwithlthel' short or long character of a single‘code‘ step”: If the tenthstep indicate the condition ‘of-seven movable devices is short, relay 'P2'is'rin tits‘ released positioniiwhen at the station by the operation of a group of indi relay R1 is operatedfto :the right. to begin” the cation‘relays K-“of the selected oiiice panel, on eleventhstep; anda circuit'iswthen closed m0 25 the sixteenth step of the code. mentarilyi from terminal 3' at the; right-hand contact‘aof relay R'overiback contact e of relay A typical group of such devices is shown in Fig. 26, illustrated asagroupof indicatingrelays including a trackistc'ring relay TKS, an approach I6,-'front contact b-of relay. LBP,; backcontact-b of relay P2, Wire vl 56 through‘relay PS to contact relay .AR, . a power-o?xrelay .POR, normal . and b ‘of relay-1D", wire v.IEELx-contact e of relay 2,'wire 30' reverse switch repeating relays NWPand RWP, and two .signal3contro1 relays LHR‘ and RHR. H2,.b'ack contact fc of‘ relay P2,.to terminal-Use that relay:v FS' is operated Ito - theileft. If’ ‘the The station apparatus;.isarr‘anged to initiate an indication.codexautomaticallydn response to a tenth step .islong. relay P2‘ ispicked .up .and held energized by relay Rifor the duration of the elev change in position ofany ofrthe indicating relays, enth step and its'contacts b and '0 reverse the 35 each’ ‘such code‘ ‘being stored ‘for transmission direction ofithe‘ flow of current. through‘relay FS, andit will-be .operate‘dito. the right. The cir when the- line. circuit ‘becomes available, by the release of the station starting-relay ST of Fig. 2C. cuits 'fori-relays'MSC‘Land COS are similarly. con Relay .ST is normallyheld energized over a stick trolled by relay ‘P2,. andirelays LI-IS ‘and RHS . circuit extending frornxterminal B at its own by‘relay'PLeach by a momentary impulse at 40 front contact mover back contact e of relay S, the beginning. of the “step following. its assigned the winding of relay ST and thence over a front step, that-is to say» following the'step the char or- back contact c ‘of eachiof the several indicat acter of iiwhich governs its operation. Relays‘ LI-IS and RHS are also provided ‘with a local re storing circuit which functions ‘in ‘a manner here-I ing relays, in series, .to. terminalC. An indication code may also be initiated manually by thetrans mission of a special ,‘frecall’f. code from the office, inaft'er described ‘:to' energize these relays in the ' by means of which relay ST Inayalso be released, ~ as explained hereinaften. Heretofore a normally ' normal : directio‘m :in response ~ to; ' the release ' of energized starting. vcircuit ofv this type has been objected .to because of the necessity‘ for a special trolling-polar stick-‘relays are described‘: .Inthe 50 adjustment of thelcontactsloi the indicating re ?rst type-i as.~ill.ustrate'd5by the. circuitforfrelay ‘ laysin order to. insure the release of the starting WS, the polar stick>relaiy isuenergized only ‘if the‘. relay during the brief period the circuit is opened _' corresponding register relay. P3 or P2‘ is picked‘ up during the transitof the contact from one posi response to along step,i-and'ilis .noneresponsive tion to another, This cli?iculty hasybeen over the .track'relay'lTR‘. . ' ' In the foregoing-two types of circuits for con iftheistep is ‘short; . In-the second type, as illus 55 come in the circuitsv as'shown by'the use ofa trated by the circuitfor relay. FSy-‘the polar. stick ' sensitive relay of the biased polar type having an relay is’energizedinlone direction if the assigned. inductance ‘ '58 ‘connected step ‘is’. long ‘and in'the opposite directionrif ‘that 7 The energy stored 'in' coil "it when relay-ST is ' energized provides ~asource of induced current 1 step is short. A, third type, not-shown, ‘is-also‘ across its ‘ terminals. _ availablegandvmay be ebtaine'd by ~ connecting. 60 for operating relay ST to its reverse position to anyof ~the-relays to “wire 158' orrl59,'ile'ading-to - open its stick circuit in response to any sudden back ‘contact “a of ‘relay Pt'vor- P i, Fig; 2A,1~instead of to wire I56 vYer; i5‘l. Assuming that one ter minal of relay PS isconnecte‘dto wire ‘I58 instead" ‘ increase in circuit resistance due to- the movement ' of "to'wir'e l56',~for-eXample,-= its other terminal 7 being connected to‘rwire HB-IasshoWn, it- will-be seenthat'relay FS will be-momentar-ily energized‘ by ' relay'R only when the assigned-step .is .short solthatv relay P2 ‘lremains 1released. It‘ vfollows of one’ of~the~indicating relay-contacts 0, even though- the time such contact is actually open ~ is substantially zero,'consequently no special ad justment of these contacts is needed; VI shall next describe the transmission of an indication code by'the apparatus of Figs. 2A, 2B and 2C, assuming the code to beinitiated as the that any-of the. polar stick ‘relays maybear 70 result of a train movementthro-ugh thetrack ranged to respond to a short step-but -to'- be non responsive when the step isflong; section VIT. The opening. of ‘contact a of the track relay TR; opens the normallyv closed stick When the - sixteenth: step c of ‘the’ control;:.icode circuit for relay TKSv extending vto terminalB .at . is reached; the line relays‘ R; remain steadily. ener- , its-‘fr'ont contact 1),‘; and ‘also vopens its pickeup gized 4 iand-"the-lltiming relayslL-l ati- eachlstation ‘circuit extending 'fromiterminal l3 atback ‘contact. 0 2,411,375? . 18 17' h of relay MSP, left-hand contact 02 of relay ST at a considerable distance from the‘ office it may be that the voltage across the line, which, varies from nearly the full voltage'of battery 8!] at the office to substantially zero at the point where the shunt is applied, will remain su?icient to keep the relays R picked upat stations near the office. These relays, however, will be released by the reversal of line polarity by relay PC. It follows that all line relays R release substantially in and front contact a of relay TR through relay TKS to terminal C, and relay TKS releases, its contact 0 in turn, opening the stick circuit for relay ST causing it to release. If the line circuit is available, the starting cir cuit is closed, extending from terminal 13 over back contacts I) of relays ST and SS, wire Hi7, contact Z) of relay RP,-contact a of a cut-out relay COR, back contacts b of relays L! and L2 through 10 unison when any relay M picks up to initiate a relay M to terminal C. Relay M picks up, com code, each relay R operating its timing relays L pleting a temporary stick circuit over its contact and ?rst counting relay 1. a extending to terminal B at wire Ml over back At each station at which relay M is not op contact 0 of relay LBP. Contacts b and d of relay erated, relay R remains released, holding relay M reverse the connections of relay R'to line wires 15 L2 energized but allowing relay Ll to release to pick up relay CD, and then relays LP, LB, LBP, , Y and Z, front contact d of relay M also closing a low impedance shunt path from line Y over back contacts I of relays CD and LPB to line Z. l and CD release in that order. Contacts 0 and d of relay M now connect the condensers of the low pass ?lter LPF' across the front contact e of relay M completes the pulsing circuit for relay T, which extends from‘ terminal B at back contact e of relay ‘CD, Fig. 2B,. over back contact e of relay l5 and back contacts g of relays ‘l, 5, 3 and l, wire I68, contact e of relay M through relay T and resistors W5 and WT to ‘ ‘ At the transmitting station, the closing of line, so that during transmission, its connections correspond to those of the one at the office. Nor mally, the impedance across the line presented by the station apparatus is materially increased, as is desirable, by disconnecting those condensers, 25 terminal C. Relay T transmits the code by *the this arrangement being shown in a co-pending operation of its contact b which is rendered e?e‘c tive when relay LBP picks up on the ?rst step application for Letters Patent of the‘ United to open its back contact J‘ in parallel therewith. States Serial No. 401,092, ?led July 5, 1941, by G. W. Baughman and N. F. Agnew, for Remote control systems. Each time relay T picks up, a low resistance shunt 30 path is closed from line Y over back contact f When the line circuit is shunted by relay M, of relay CD, front contact I) of relay T and front the associated line relay R releases and the in crease in current delivered by battery 80 causes contact d of relay M to line Z, and at the same time, the circuit for relay R which‘ now extends transformer RT,v Fig, 1A, to deliver an impulse from the positive wire Z over front contact 11 operating relay OR to reverse substantially in 35 of relay M, back contact b‘ of relay T, resistor unison with relay R. Wi, relay R, front ‘contact 19 of relay M to wire Relay R operates the associated timing relays Y, is opened by relay T, thereby releasing ‘relay, and relay I, the closing of contact 0 of relay LB R more quickly than if it was merely short cir completing the normal stick circuit for relay M‘ cuited by the ‘closing of front contact b of re—. extending over wire H8 and back contacts e of 40 relays l6 and CD‘ to terminal B. Relay OR operates the timing relays 0L,’ relay I and relay E, as on the ?rst step of a con trol code, and in addition a circuit is completed from terminal B at the right-hand contact a of relay OR over back contact 71. of relay OLBP, back contact I) of relay OM, back contact d of relay 0! 6 through relay PC to wire I‘! and thence to terminal C at contact a of button CB. Relay PC therefore picks up and its contacts b and d reverse the polarity of the ‘current delivered to the line, while its contact 0 completes a circuit energizing a slow pick-up», slow release repeating lay T. ‘ > . . Although the ?rst stepIof ‘an indication code is short in comparison with the ?rst step of a control codeait is slightly longer than the other short steps, since it begins .beforerelay T picks up, and because relayT‘is held energized until relay LB picks up, which occurs shortly after relay l picks up to open the ‘pulsing circuit, clue to‘ the provisionv of a connection from terminal B, at back contact e ‘of relay LBP over back contact at of relay LB to wire; I68.‘ The response of the apparatus at the transmit, ting station as required to allow the transmission to continue is also dependent ‘upon conditions at relay PCP. ’ ‘ o?ice. Since the connections of relay R tov The‘sudden variation in the line current due 55 the the line have been reversed by relay M, relay R to the operation of relay PC is devoid of effect upon relay OR for the reason that when relay PC picks up, the secondary of transformer RT is momentarily short circuited over the front con- ' tact c of relay PC and back contact 0 of relay PCP, and the lower winding of relay OR is ener gized in the reverse direction over the circuit ex tending from terminal B at back contact b of relay PCP, front contact 1‘ of relay PC, and back contacts 0 of relays X, OM and OT through relay DR to terminal 0. Relay PC is held energized over a stick circuit including its front contact a and front contact h of relay OLBP until relay Ol6 picks up upon the return of relay OR to normal at the end of the code. ‘ The shunt across line wires Y and Z applied by relay M at the transmitting station as de scribed will also ‘short circuit and consequently ‘ release the line relays R at stations more remote 1 picks up to begin the second step only if relay PC has been picked up to reverse the polarity of the line current, this indicating that the o?lce appa ratus is in- the proper receiying condition with relay OM released, ' i . 1 The code call ‘steps of the indication code are generated by relay T inthe same ‘manner as by relay OT in the control codealready described. Assuming‘this to be 234, the second step is‘ pro longed'by the closing of a‘hold-down circuit for relay T extending from terminalB over back con—. tacts c of relays ST,‘ SS and S, back contact g of relay GA, back contact ,6 of relay FA to wire 132,: thence over contact 0 of relay 2 and back contact J‘ of relay CR, wire I62, contact I of relay Mhand. back contact 0 of relay T'to its lefteha'nd terminal, thereby ‘short circuiting relay ‘TL , On the ‘second step, relayFA picks up in'response to the re lease of relays L2 and and‘its contact e‘tra‘ns fromth'e oilice. ‘If the transmitting station is 75 fers the connection of‘ terminal]; from wire I32. 19 2,411,375 20 lay T remains released and relay M releases, re~ to wire I33, opening the hold-down circuit for re lay T to allow it to pick up to begin the third step. The third step is prolonged by the operation of the stick circuit for relay T extending from termi nal B over front contact e of relay FA to wire I33, versing the connections for relay R to render it responsive only to line current of normal polarity. ‘At the‘oii‘ice, relay OR is operated to normal, ' thence over contact 0 of relay 3, back contact e of back contact at releases relay PC‘, thereby restor ing the line polarity to normal so that relay R energizing relay OIS, which relay by opening its relay CR, wire, ISI, contact a of relay T and the Winding and front contact'c of relay T and re sistor W'I to terminal C. On the third step, relay GA picks up in response to the release of relays LI and LP and its contact 9 transfers the con will remain steadily energized after relay M re- " leases.- Relay PC releases relay PCP,‘ and relay OR release-s ‘relays 0L2, OLP, OLB, OLBP and V OLI, in’ order. . . Relay OR remains in its normal position and is not affected by the operation of relay PC be nection of terminal B from wire I33 to wire I34, ' opening the stick circuit for relay T to allow it to release to begin the fourth step, which like the second, is prolonged by the operation of a hold down circuit for relay T, the circuit for generating circuited over back contact 0 of relay PC and front contact 0 of relay PCP, and relay OR is. the long fourth step including front contact g of relay GA, wire I34 and contact 0 of relay 4. On PCP releases over the circuit extending from ter cause when this occurs transformer RT is short held energized in the normal direction until relay the fourth step, the station selector relay S picks minal O through the lower winding of relay OR, up in response to the release of relays L2 and LP, 20 back contacts e of relays OT, OM and X, back the opening of back contact 0 of relay S allowing contact 1' of relay PC, and front contact a of relay T to release to begin the ?fth step. relay PCP to terminal C. When relay S picks up it completes the circuit The restoration of the line polarity to normal for the repeating relay MSP, extending from ter by relay PC causes the line relay R at each of minal B at front contact g of relay M, Fig. 2A, the other stations to pick up. At these stations, over wire I69, contact b of relay S through relay relays LI, LP, LB and LBP pick up‘ and then MSP to terminal C. Relay MSP therefore picks relays L2, LP, LB, LBP and LI release in that up on the step corresponding to the last digit of order. the code call, remaining energized until the end At the transmitting station, even though relay of the code. Since the pulsing circuit for relay T‘ functions in the same manner as that for relay OT already described, it will be clear that if relay S is op erated on the fourth step, the ?fth to eighth steps will be short steps, generated by the opera tion of relay T over its pulsing circuit. Relay CR M releases at the exact instant that the line polarity is restored to normal, relay‘ R may be momentarily, deenergized, but since relay I6 is picked up, its contacts d and e connect the right hand and left-hand contacts a and b of relay R .. together so that the circuits controlled by relay " ‘R remain in the same condition as if relay R remained steadily energized.‘ Consequently the picks up on the eighth step over the circuit ex tending from terminal B at contact d of relay timing relaysL at that station release in order, S, wire I46, contact I of relay 8 through relay substantially in unison With those at the ofiice CR, to terminal C, relay CR completing its stick 4.0 and slightly in advance of those at the other sta circuit extending to terminal B at wire Hill by tions. Relay MS? is released by relay M, relay It closing its front contact a. is released by relay LB and relays CR and S are When relay CR picks up, it completes a pick released-by relay LBP. When relay. M releases, up circuit for the normally energized starting its back contact 21-, Fig. 2B, connects wire, I23 relay ST extending from‘ terminal B at contact 0 over back'contact‘ h'of relay I to wire IIli ‘to maintain the temporary stick ‘circuit forrelay of relay CR over front contact me of relay 8, front ST closed after relay LB releases. When relay S contact in of relay M, wire II4, front contact J‘ of releases, the dropping of its continuity transfer relay S through relay ST and coil ‘Ill, in parallel, and thence over the front or back contacts 0 of contact 6 restores the normal stick circuit over the indicating relays TKS, etc., to. terminal C. Relay ST picks up and establishes a temporary stick circuit extending from terminal B at its which relay ST is held» energized until a change front contact a over front contact 6 of relay S, It‘will be seen that all coding unitsarereé stored to normal and placed in the proper re ceiving condition prior‘to the release of relays occurs in the position of one of the indicating relays to‘initiate a new code. wire I I3, front contact d of relay LE, to wire I Iii, and thence as traced above through relay ST and coil 10 to terminal C‘. On the eighth step, relay CR establishes con . " OLE‘ and LI to condition the system for the trans’ mission of the next code. nections from terminal B at the contacts 19 of . ' . ‘ Achange in position of one of the indicating the indicating relays NWP, TKS, etc. of Fig. 20 relays may occur during the transmission of the over contacts a to yof relay MSP, wires I39 to 60 indication code just described. If this occurs I46, completed successively over contacts 5‘ of prior tov the transmission-of any of the indicating I relays I to ‘I on the ninth to ?fteenth steps of the steps nine to ?fteen, relayiST will be reenergized . code, either over contact e of relay LI and contact I) of relay LP, in parallel, and front contact 0 of relay CR to wire IBI, or over contact 6 of relay 65 L2 and contact 0 of relay LP, in parallel, and‘ front contact 1‘ of relay CR to wire I62, to hold onthe eighth stepand but one/code will be trans mitted. Since the pick-up circuit for relay ST is opened at the beginning of the ninth step, the. temporary stick circuit by ‘which relay ST is held energized will bev opened to cause it to release, again, if’ a change in the vposition of any‘of the indicating relays, occurssubsequent to the trans available for indicating the positions of seven 70 mission of the eighth step.’ Thus a: newindica indicating relays at the same location.» tion codetwill be transmitted to indicate the new relay T up or down, as the case may be, until relay LP releases, therebyv rendering these steps When the sixteenth step is reached, relay R at the transmitting station picks up, energizing relay l6 which opens its back contact e to dis connect terminal B from wires I68 and H8. Re condition. " ‘ w w _ " t ‘ It may ‘also occur, dueto afault, that the trans- - a mission} is interrupted before the; sixteenth step 75 is reached to restore the normal stick circuit for V £4112 ‘3175"; 21 22 relay ST. If an extended pause in theoperation of relay R. occurs after relay ST has been picked up, relay LI or L2 will release, releasing relay LB. 2C,‘over a contact of an‘ indicating relay, the In this instance relay LB will open its contact at before relay M releases, to release relay ST and one of the register'relays 9 to I5 will be‘ picked up. ‘I If the ninth step is long, ‘for example, relay OLI ‘ thereby condition the apparatus ‘to retransmit will release closing its‘ back contact b to complete a‘ circuit from terminal B at contact a’ of‘ relay OLBP‘ over‘ contact 1‘ oferelay PCP, back contact corresponding step of the transmitted code will be prolonged‘ andat the o?ce, the corresponding the code in its entirety when the line becomes available. ~ ‘ = ~ Heretofore in connection with starting" relays of the normally energized type, as illustrated for example by the relay S of the Letters Patent of the United States No. ‘2,273,231, issued February _ d of relay‘OLI, wire 63, front contact b oflrelay OCR, contact e of relay OI through relay 9 to terminal C, relay 9 picking up to completeia stick circuit extending to terminal B at wire 60 over its front contact“ a, and also closing its contact 1'7, 1942, to C. S. Snavely 'et al., it has been nec essary to provide a repeating relay SP, which is restored to normal at the end of a complete code, in order to make sure that a code interrupted on any of the steps following the one on which the starting relay is picked up, will be retransmitted. This result is attained in accordance with my in vention by the provision of a temporary holding circuit as above described, in addition to the nor mal holding circuit for the station starting relay ST. ‘ b‘t'o connect terminal B to wire 49. 15:11 ‘ On the sixteenth step, relay OIB picks up, clos ing a circuit from terminal B over front contacts 0 of relays OCR. and OCD, Fig. 1B, contact 1‘ of relay OIS, wire 56,,co1l1tact b of the selector relay 224s throughthe associated delivery relay 234D 20* to terminal C. Relay 234D therefore becomes energized to‘ operate the indication relays K of the group which it controls in accordance with the positions of the register relays 9 to I5.‘ ‘ Relay ‘ I shall now describe the operation of the office apparatus of Figs. 1A, 1B and 1G in receiving an indication code. It will be understood that relay 234D opens the stick circuits for‘the relays K and .;: prepares pick-up circuits for each'of these'relays, extending over wires 49 to 55 to terminal B at the front contacts b of relays 9 to I5, respectively, the position of which indicates the condition of the indicating relays of the group controlling the OR is operated, through transformer RT, to the right on each odd-numbered step and to the left on each even-numbered step, and thus operates its timing and counting relays through sixteen steps in unison with the corresponding relays at the transmitting station; On the ?rst step, relays OLI, OI, E, PC and PCP pick up as already described, as well ‘as relays 0L2, OLP, OLB and OLBP, but relay OLI does not ‘release because the ?rst step is short. turn releases relay PCP. The release of‘ relay PC restores the linev polarity to normal, relay OR ‘being held normal over back contact f of relay PC and front contact a of relay PCP until relay Selected ones of the of?ce relays F, G and ‘S - PCP releases, relay OR. being 'disconnectedfrom A transmission of the code. The opening of back contact (1 of relay OI6 on the sixteenth step releases relay PC, which in‘ pick up on the steps Corresponding to the digits of the station code call. More particularly, in, response to the code call 234, relays 2F and 23G are operated on steps two and three, ‘and relays ' ‘234s and SP‘ on step four. “In the receiving con dition, back contact at of relay OLP in the circuits for these relays is bridged by front contact [of ‘ relay PCP, so that these rela‘ysare picked up upon the closing of back contact d of relay OLI or 0L2, on the long steps. ' ‘ > 3 e The energization of ‘relay PCP also prepares ‘a circuit extending from‘terminal Bin Fig.'1A overfront contacts 0 of relays OLI ‘and 0L2, front ‘contact e of relay PCP, wire 59, front con tact c of relay SP through the‘upper winding of relay ‘0CD to terminal G. ‘Since’ relay ‘SP is picked?‘ up over a back contact of relay OLI or 0L2, the circuit‘for relay 'OCD is held ‘open on ‘ ‘ the step on which relays S or ‘SP are‘operated, and‘closes as soon as relay OLI or ‘0L2 picks‘ up at the beginning of the next ‘I stepfollowing the ?nal digit of the station code call, that is, On the ?fth step 1when the code call is 234. ‘When re lay OCD picks up it completes a-stick circuit transformer ET by ‘the opening of back contact 0 of relay M6. The'o?ice timing relays then-re lease in the normal order, relay OLI being the last to release. Relay OLB releases relay'OIIS, which releases‘ relay 234D, reestablishing the stick circuits for the indication relays K which were energized over wires 49 ‘to 55. Relay OLBP < releases relays OCR, 0CD, SP and 2343, as well I as the energized relays of the group 9 to I 5..‘ In the foregoing, it was assumed thatthe code. was initiated by the release of the track relay TR,: relay I I] being energized on the tenth step‘ and; relay TK on the sixteenth step to light the lamp TKE, and also, if key 'I‘KB is closed to operate the bell relay-BR momentarily over contact b of relay TK to actuate the single stroke bell‘BL. If this code is repeated, relay ‘TK remains picked up and the bell BL is notzoperated, as will be readily apparent. Front contact a of relay TK provides a connection from terminal B for ener gizing the pen magnet PM of a graphic recorder such as is usually provided in systems of this ' character. over it’s‘contact a and lower winding'extending to terminal B at wire" 69. 'In order to insure that magnet PM will be oper ated iii-response to each train movement through the controlling track section, even though the line viously ‘Relaydescribed. 00R picks Front up on contact thefeighth 7‘ ofstep relay as PCP“ pre-‘? circuit does not become available for, the trans mission of the indication code until after the maintains the connection from terminal Bat wire . Glover back contacts (2 of relays 0L! and 0L2 to ‘ wires 63 and 64 after relay OCR picks up',‘am1 the closing of front’ contacts b and d of relay OCR track section has been vacated, a storing relay v TKS is provided as shown in Fig. 20, which relay is normally held energized over a stick circuit _ extending from terminal B at its front contact prepares circuits extending from wires'?s and'litl ‘ to b over front contact a of relay TR through relay to contacts e‘ of relays OI to 0]’ whereby a series TKS to terminal C. ‘The release of relay TR‘ of registerrelays 9 to I5 arerendered responsive when a trainenters section IT therefore releases ;_ tothe character of the correspondingly numbered. relay TKS to open itsstick circuit and to ‘con steps of the code. .That is, when terminal B is} . . nect terminal B over itsfback‘contact b, to contact;_ connected to any one of the wires I39 to ‘I45, Fig?’ a b of relay MSP, to condition the unit to ‘transmit 2,411,375 23 24 a track occupied indication. Relay ST is released by the dropping of contact 0 of reIayITKS, and the normal order due to the deenergization of re~ lay L2, relay Ll being the last to release. opens its contact din the pick-up circuit for relay If a control code is terminated on an even TKS extending to terminal B at back contact 72 numbered step prior to the sixteenth step, due to of relay MSP, so that relay TKS remains released 01 the'failure of relay OT to pick up, relay OR is until the track occupied code is transmitted. held normal and the timing relays releasein the normal order, relay OLBP releasing the count-v During the transmission of this code, back con tact h of relay MSP opens prior to the closing of ing and selecting relay circuits and also releas ing relay OM, relay OLi, being the last to release. contact (1 of’ relay ST, which occurs on the eighth step, and when back contact h of relay MSP 10 The station line relays remain steadily energized closes again on the sixteenth step, relay TKS be and their timing relays release in the normal or— comes reenergized, provided relay ST is picked der as ‘at the end of a complete code, relay Li up, indicating that the track occupied code has being the last to release. . v been transmitted ‘andprovided also that relay If an indication code ‘is terminated on an odd TR is picked up. When relay TKS picks up, the opening of its back contact c‘releases relay ST again, to initiate a code for indicating the track numbered step, as for example, would be the case if relay T remainedpicked up due to a fault, relay OR remains reversed until relay OLBP re leases, relay OL2 remaining picked up. Relay clear condition, but since relay ST is extremely OR is restored to normal upon the closing of back fast, the energizing circuit for relay TKS is opened by relay ST before relay TKS is fully 20 contact J‘ of relay OLBP‘ over the circuit above picked up to establish its stick "circuit. A con denser CI of relatively large capacity-provides sufficient energy‘, storage to prolong the energiza tion of relay TKS until its front contact b closes to establishits stick circuit, under the condition 2.5 described.’ - ~ ' 1 traced which includes front‘ contacts of relays PC,’ PCP and 0L2, and back contacts I of relays OLBP AND'OLI. At the transmitting station, relay R remains released, and the timing relays Ll, LP, LB and LBP release. Relay LB releases relay M, which Relay TKS also controls a circuit for restoring the polar stick signal control relays to normal relay releases relay T. and removes the lineshunt when a train enters the track section to release tions for relay R so that relay R ‘remains re applied by relay T,-and also reverses therconnec relay TR, to prevent the clearing of the signals 30 leased, the apparatus assuming the. same. condi automatically when a train vacates the track sec tion as at the other stations where relay R and ' tion, no additional repeating relay being required, this circuit extending from terminal B at back the timing relays stand released with relay LZ' contact b of relay TR over front contact a of picked up. When relay OR is restored to normal, the of?ce , relay TKS through the lower windings of relays 35 timing relays are reenergized and relay PC is'de energized and releases before relay OLBP picks LHs' and Rl-IS in- series, to .tBrminalC. up. The office timing relays them release in the I shall next describehow the system is restored norma1 order, relayOLl being the last to release. to normal in the case of a fault. When relay PC releases, it restores the line po A control code may be terminated on an odd numbered step due to a fault, relay OT being held 40 larity to norma1 so all the line relays Rpick up in unison,v reenergizing their timing relays, and energized over wire 88, for example. Relay OR the timingrelays at each station then release in 'V is then held reversed until the timing relays OLI , the normal order, qrelay Ll being the last to 1OLP, OLB and OLBP release, relay 0L2 remain ing energized. ‘Relay OLBP releases relay OM and opens the counting: and selecting relay cir cuits. The release of relay OM ‘with relay OR reversed ‘allows relay PC to pick up. Relay OM also releases relay OT, and relay PC picks up relay PCP. ' ' ' release.‘ , I . 7 M > - If an indication code is terminated on aneven numbered step prior. to the sixteenth'step,v due to the failure of relay T to pick up; relay OR, remains normal-until the timing relays 0L2, OLP, OLB and OLBP release, the closing of back I At‘ each station, relay R remains released and 50 contact 1‘ of relay OLBP completing-‘a circuit for operating relay OR to reverse extendingfromiter- -. the'timing relays release in the same order, relay minal B at front contact (1 of relay-PCP, back 0L2 remaining energized. Relay LBP opens the contacts 1" of relays 0L2 and OLBP, front contact I‘ counting-‘and selecting relay circuits to prevent b of relay PCP, front contact 1‘ of-relay PC and . the line circuit, but the relays R do not pick up 55 back V contacts e of relays'iX, OM and OT through ' further reception. The release of relay OT closes relay OR to terminal 0. because ‘the polarity has been reversed by lay PC. ~ ' At the transmitting station, relay R remains’ a When relay PCP picks up, relay OR is operated to normal over the circuit from ‘terminal 0 picked up and the timing relays L2, LP and LB, release. 'Relay'LB releases relay M and reverses , the connections for relay R So that relay R re, through its lower winding and back contacts e 60 leases, reenergizing the timing relays'whichthen; of relays OT, OM'and X, front contacts 1‘ and b release in the order Ll , LP, LB and LBP, the ap - of relays PC and PCP, front contact I of relay paratus assuming the same conditionas,atthe__ 0L2 and back contacts f of relays OLBP and 0L! other stations where relay R and the timing re- ' to terminal C. The‘ office timing relays are there-‘ 65 lays stand released, with relay R2 picked up. ,, by reenergized and relay PC‘ is deenergized, relay PC releasing before relay OLBP’ picks up. The office timing relays then release in the normal ore der due to the deenergization of relay 0L2, and relay PCP also releases, relay OLi being the last 70 to release. 7 . When relay PC releases it restores the line no larity to normal so all'the line relays R pick up in unison, reenergizing their timing relays, and At the o?ice, relay OR is reversed upon the rev-‘1 lease of relay OLBP, and since the'pick-up cir-l cuit for relay PC. is closed when its stick circuit . opens, relay PC ‘remains picked up. The office timing relays are reenergized and then release in the order OLI, OLP,'OLB. and'OLBPjrelay 0L2 remaining picked up. Relay OR islrestore’d to normal upon the closing of back contact I of relay OLBP over the circuit above traced which the timing relays at each station then release in '75,in_cludes .front contacts of relays, PC,‘ PCP and.