O_ct. 15, 1946. 2,409,335 Y. Z. VON STACKELBERG HYDRAULIC BRAKE SYSTEM Filed NOV. 22; 1944 ____ J Yui*geh Z.von S’rackelberg Patented Oct. 15, 1946 2,409‚335 UNITED STATES PATENT OFFICE 2‚409,335 HYDRAULIC BRAKE SYSTEM Yurgen Z. von Stackelberg, Baltimore, Md.‚ as signor to The Glenn L. Martin Company, Mid dle River, Md.‚ a. corporation cf Maryland Application November 22, 1944, Serial N0. 564,594 11 Claims. (GI. 188—152) 2 This invention relates 110 a hydraulic braking system,- particularly for aircraft, and its prima object is to provide a hydrauli<: braking system ‚including an emergency fluid system whereby the bl‘akes may be operated in the event the ?uid pressure pump fails o1‘ where the normal ?uid line conveying fluid 110 the brakes has been rup tured. ~ It is more or less <:onventional in aircraft brak ing Systems to energize the wheel brakes by utiliz ing a ?uid pressure system comprising a ?uid reservoir and pump connected thereto fur forcing ?uid under pressure to foot-controlled valves which are attached to the right and left rudder pedals of an aircraft for operation by the pilot, With the Fluid under pressure controllecl thereby communicating With the wheel brakes for apply ing actuating pressure thereto. It is obvious that the fluid pressure lines leading from the 15001: quires a major overhaul 0f the system beqause of the air in the syste‘ms. ‘ In the present invention, the hydraulic braking system include3 a closed, normal ?uid system for the brakes, comprising a ?uid reservoir and pump, foot; control valves attached to the rudder pedals for passing ?uid to the wheel brakes, and a pair of four-way valves inserted in the fluid 1ines lead ing from the foot operated brakes, whereby ?uid 10 under pressure is normally passed therethrough _to the brakes.. A vent; line is provided from shut tle valves on the brakes back through the tour Way valves and thence 110 a common discharge line, which is connected to the r€servoir. A hy draulic fluid accumulator of any accepted de sign is placed in the ?uid line between the pump and the foot oper2mted valves, with a check valve interposed in ‘ehe ?uid 1ine betvveen the pump and the accumulator. With this arrangement, the accumulator is kept under full pressure ‘als all times and acts as~ a pressure equalizer on the line. Upon failure of the pump, tlr1e check valve operates to prevent escape of ?uicl from the ac controlled brakes on the rudder pedal to the wheel brakes a1‘e quite vulnerable and thai; if these lines rupture there would be no pressure available for actuating the brakes. Furthermore, this dangerous condition may occur if the pres cumulator back through the pump, and vthe pres sure pump develops any mechanical di?lculty 25 sure is maintained at the brake va1ves by the accumulator. and fai1s to maintain the necessary ?uid pres sure in the operating 1ines. ‘ ‘ “ A slhuttle valve similar to that illustrated in It is usual to carry a compressed air bottle hav Overbzäke Patent N0. 2,300‚694,dated October 3, ing a manually controlled valve thereon and a separate air circuit to the brakes through shut tle valves located adjacent the brakes whereby if the normal ?uid 1ine lacks suf?0ient pressure 130 operate the brakes, the air bottles may be opened to shift the shuttle va1ves and close off ?uid therethrough and to permit air from the compressed supply 120 energize the brakes. Hew ever, this type of emergency brake operator has several inherent disadvantages inasmuch as the 1942‚ is placed on each brake. The valve forms a ?tt‘lng to- Which the normal pressure line and the ve'nt 1ine which also forms the emergency ?uid pressure line, are connected. The four-way valves controlling the normal and emergency conduits are preferably made in a single unit and are manually operated ~by ‘ehe pi1ot, when the “feel” cf the pedal valves controlling the regular brake lines indicates there is insu?icient ?uid pressure to operate the brakes. By merely f1ip ping a 1ever, the plugs of thefour-way valves shift; the ?uid pressum from the control valves, air bottle permits only a Single operation of the brakes, and more important, after the emergency 40 opera’oi0n, ‚the entire hydraulic system is con from the normal line, into the emergeney line through the shuttle valves. I1: Will be appa3rent ' taminated wi‘oh air and. it is ther1 necessary to that When the normal ?uid lines are used, the disconnect and purge the Whole braking system ' emergency lines act as vents therefor and com-v before normal fluid operation can again be ef fected. The use of compressed air in the brakes, ' versely when the emergkency lines am used the because there is no- control over its application 110 the brakes, locks the aircraft wheels and in mos't cases causes the ti'res to be ruined in arresting the plane; As before stated; the greatest di'sad vantage in ‚such an em€rgency air system is that the WhOle system must be bled of the air before repairs can be made and the hydraulic ?uid sys normal lines act as a vent, and this~ ventlng operation and use of shuttle valves positively prevents any hydraulic lockin the system. Fur . thermorejthere is a great advantage attendant to the use of this type of hydraulic system over the air bottle heretofore proposed, as no air is aclrnitted into the ?uid System. 'I‘he Check valve referred. to prevents any recession of ?uid from ‘gern fails because of the non-operation of the ‘ehe accumulator‘either Joy fai1ure 0f the pump ?üid pump, such a minor mechanical falilure re or rupture of the normal ?uid pressure lines' 2,409,335 3 leading from the foot brakes to the wheel brakes. The attached drawing 15 a diagrammatical lay out of a ?uid system embodying the principles of this invention, but it will be obvious that these principles can be incorporated in ?uid braking systems of other design. Speci?cally the normal 4 vent for said shutt1e valve through said ?ow com trol valve. 2. A hydraulic brake system comprising a res_ ervoir, a pump, a pressure control valve, a ?uid line and a brake, interconnected to cooperate to deliver ?uid under controlled pressure 110 said brake, an accumulator connectecl to said 1ine be ?uid circuit extends from the ?uid reservoir R tween said pump and said. control valve to equal having a vent V thr_ough pump P and Check va1ve ize the pressure in said line, said ?uid line ex CV to aceumulator A and through main fluid line l to foot operated valves 5 and 5' which 10 tending from said pressure control valve to said brake including a manually operated ?ow control may be attached to the rudder pedals of the va1ve connected to receive ?uid under pressure aircraft and operated Joy linkages 7 and 'l’‚ re from the out1et of said pressure control valve, a spectively. As shown, the main ?uicl 1ine l is shuttle valve mountecl on said brake, a pair of branched. into the casings 0f brake pedal valves 5 and 5', and these valves ma-y De individually 15 flu_i_d lines extending from said ?ow control valve vented through vent 1ines 29, 29’ to ma‚in retllI-Il to the inl_et ports of said shuttle valves, said 1ine 2T. "I‘he four-way valves I5, I5’ receive ?uid manually operated valve so connected that fluid through lines H, H’ connected to the foohop erated valves 5 and 5’. In the position shown, under pressure may be di1‘ectecl through one 01‘ the oth„er of the brake lines to said shuttle valve, the plugs of the four-way valves pass ?uid to the 20 the 1ine through Which ?uid pressure is not di rected. a?ords a vent for said shuttle valve normal brake operating conduits I9, l9’ through through said ?ow contro1 valve. ~ shuttle valves 2 l, 2!’ to the whee1 brake B. Vent 3. A hydraulic braking system for vehicles com lines are provided via ’the four-way valves prising a brake, a reservoir, a pump having the through emergency lines 23, 23’ through the passa€€s of valves I5, l5' and vent line 27 C011 25 inlet side connected to said reservoir, an ener gizer-accumulator connected to the line on the nected _to the top of reservoir R. outlet side of the pump, a check valve between If the pump P falls or if the normal ?uid 1ines the inlet to the accumulator and said pump, a I9, I9’ are shot away the pilot operates lever l'l pressure control valve in said line controlling the and. moves it from the normal to emergency 100 sit‚ion indicated by the letters N and E 150 rotate 30 pressure of ?uid through the brake line to the brake, said brake line including a ?ow control the plugs of the four-way valves I5, I5’ whereby valve, a shuttle va1ve mounted on said brake and the ?uid circuit permits ?uids from the ever a pair of conoluits extending from said ?ow con gharged accumulator A t0 pass through 1ine I, tro1 valve to the inlet ports of said shuttle valve; valves 5 vand ‚5' as in normal Operation, and thence t0ßm€rgency lines 2.3, 23' and through the shut- ' said ?ow control valve connected to said pressure control valve to receive ?uid therefrom and di t1e valv‚es to the brakes. The normal lines I9, rect it through either of said pair o-f lines to said I9’ then vent; the shuttle valves and prevent any shuttle va1ve, the other line affording a vent for hydraulic lock from occurring. It is preferable said shuttle valve through said ?ow contro1 va1ve. 130 Vent the foot-operated valves 5 and 5’ inde 4. A hydraulic braking system for vehicles com pendentl5n and this is sho-wn by lines 29, 29' 40 prising a fluid circuit including a reservoir, a joined to the main return 1ine 2T. pump for maintaining the ?uid in the circuit; As be‚for_e indicatecl, the accumulator contains under pressure, a brake, an accumulator secured su?lcient ?uid pressure to 0p_erate the brakes a ‘so the line on the outlet side of the pump acting number of times, and ‚by reason of the check valve as a pressure equalizer, means to prevent ?ow of CV the accumulator is constantly Charged and ?uid frbm said accumulator through said pump, available for instant use. When lines I9, I 9’ a pressure control va1ve for controlling the ?ow are shot; away, the ?uid escapes therefrom and of ?uid to said brake on the vehicle, a normal the system does not become pressure locked. ?uid pressure line extending from said pressure The mechanism described a?orcls an alternate control valve to said brake, a second pressure line ?uid pressure source that operates the brakes in extending from said pressure control valve 1:0 said the same manner and With the same “feel,” after brake, a manually operable ?ow control valve lever I’! has been moved from the normal to the meang interposed between said pressure control emergency position. valve and said brake for directing ?uid under ‘It is to be understood that certain changes, a1 pressure through either the normal line or the. terations, modi?cations and substitutions can be secondary line. V made without departing from the spirit and scope 5. A hydraulic braking system including a plu of the appended claims. r-a1ity of brakes, a ?uid reservoir, a pump and ?uid pressure lines each having a pressure control I claim as my invention: va1ve for delivering, ?uid under controlled pres 1. A hyclraulic brake system comprising a res sures from the pump to each brake, an accu ervoir, a pump to deliver fluid under pressure from mulator interposed in the system between the the reservoir to a ?uid line, and a brake‚ a pres pump and the pressure control valve to equalize sure _contro1 valve in said ?uid 1ine controlling the pressure in the system and a manually op the ?ow of ?uid to said brake, said ?uid line erated ?ow control valve in said system for di extending from said pressure control valve to said recting ?uid under pressure from each of said brake including a ?ow control valve connected to pressure c_ontrol valves 120 saicl bra-kes through receive ?uid under pressure from the outlet of one or the other of separate ?uid pressure lines. said_ pressure control valve and a shutt1e va1ve 6. A hydraulic brake system comprising a res on said brake, a pair of ?uid lines extending from erv‚oir, a pump 130 deliver fluid under pressure s_ai<_:1 ?ow control valve to the inlet ports of said f‚r‚om the reserv‚oir 130 a ?uid line, and a brake, a shut‚tle valves, one o_f said lines constituting the pressure control val.ve in said fluid line control normal pressure line am]. the other an emergency ling the ?ow 0f ?uid to said brake, said fluid line pressure lin‚e‚ said ?ow control valve adapted to extending from said pressure control va1ve to said direct ?uid through either the normal or emer brake including a ?ow control valve connec'oed to gency pressure line, the other line ‚afforcling a B 2,409,835 5 receive ?uid under pressure from the out1et of said pressure control valve and a shuttle valve on said brake, a pair of ?uid lines extending from said ?ow control valve to the in1et ports of said shuttle valves, one Of said lines constitutiug the normal pressure line and ‘ehe other an emergency pressure line, said. ?ow control valve being a man 6 and said brake and an accumulator connected to the line between the pressure control va1ves and the pump a. Check valve between said accumula tor and said pump, said accumulator acting to equalize the pressure in the system maintained by said pump and act as an emergency source of pressure upon failure of the pump. 10. A hydraulic brake system comprising a res through either the normal or emergency pressure ervoir, a pump 120 deliver ?uid under pressure line, the other line affording a vent for said shut 10 from the reservoir to a‚ ?uid 1ine, and a brake‚ a tle valve through said ?ow control valve. pressure contro1 valve in saio‘l ?uid 1ine control— ual1y operable valve 130 selectively direct ?uid 7. A hydraulic brake system comprising a res ervoir, a. pump, a Dressure control valve, a, ?uid 1ing the ?ow of ?uid 110 said brake, said ?uid line extending from said pressure contro1 valve to 1ine anal a brake, interconnected to cooperate to said brake including a, ?ow control valve can deliver ?uid under controlled pressure 170 sa‚id 15 nected 130 receive ?uid under pressum from the brake, said ?uid 1ine extending from said pres« out1et of said pressure control valve and a shut sure control va1ve to seid brake including a. ?ow ’ole va1ve on said brake, a, pair of ?uid lines ex control valve connectea to receive ?uid under tending from said. ?ow contro1 valve 130 the inlet pressure from the outlet of said pressure control ports of seid shuttle valves, one 0f said lines con valve, a. shu’ßtle valve mounted 0n said brake, a 20 st‘ituting the normal pressure line and the other pair 0f ?uid liues extending from said ?ow con an eme1‘gency pressure line, said ?ow control trol valve to the inlet ports of said shuttle valves, valve adapted 170 direct ?uid through either the said ?ow control valve so connected that ?uid normal 0r emergency pressure line, said lines be under pressure ma.y be directed through one 01‘ ing so connectecl that one will serve a.s a Vent the other of the brake 1ines tdsaid shutt1e valve, 25 line for one side o1" the shuttle valve when the the other 1ine aifording a vent for said shuttle other 1ine Conducts fluid under‚pressum to the valve through said ?ow control va1ve. other side of said shuttle valve. 8. A hydraulic braking system for vehicles 11. A hydraulic brake system comprising a, res comprising a reservoir, a. pump having the inlet ervoir, a pump 130 deliver ?uid under pressure side connected to said reservoir, an equalizer 30 from the reservoir to a ?uid line, anti a brake, a accumulator connected ‘so the line on the outlet pressure contro1 va1ve in said Fluid 1ine control side 0f the pump, a, check valve between the inlet ling the ?ow of ?uid to said brake, said ?uid line to the accumulator and said pump, a pressure ‘extending from said pressure control valve ’oo said ' control valve in each 1ine controlling t‘ne pressure brake including a, ?ow control valve connected to 0f ?uid through brake lines to brakes, each of receive ?uid under pressure from the outlet of sa‚id brake 1ines includi_ng a, ?ow control valve, said pressure control valve and a shuttle valve on a shuttle va1ve mounted on said brake and a pair said brake, a pair of ?uid lines extending from of conclui’cs extending from said ?ow control valve said ?ow contro1 valva 120 the in1et ports of said 120 the in1et ports of said shuttle valve, said ?ow shuttle valves, one of sa.id lines constituting the control valve connected 1:0 said pressure control 40 normal pressure line and the other an emergency valve to receive ?uid therefrom and direct it pressllre line, said ?ow control valve adapted to through either of said pair of 1ines to said shuttle direct; ?uid through either the normal 01‘ emer va1ve, the other 1ine aifording ‘a vent for said gency pmssure 1ine, said 1ine being connected shuttle valve through said ?ow control valve. through the ?ow control va1ve so that when one 9. A hYdraulic braking system for vehic1es 1ine conductg ?uid under pressure 120 one inlet comprising a‚ reservoir, a pump for maintaining port of the shuttle va1ve, the other line serves ?uid in the system under pmssure, conduits ’ex as a Vent line from the other port 0f said shuttle tending from said pump to deliver ?uid under valve through the ?ow control va1ve. pressure 1:0 the brakes of said vehicle; pressure »COI11ZI'OI valves in said. conduits between said pump YURGEN Z. VON STACKELBERG.