Патент USA US2406854код для вставки
Sept. 3, 1946.. D. SAMIRAN‘ 2,406,854‘ MULTIPLE TANK- FUEL SYSTEM~ , Filed Feb. 12, 1943 3., Sheets-Sheet 2 441' 49 i5 - 3 - 5, ‘ 3/ ‘ '47; ‘53 4-5 '55 , WQ‘ILIIIII Ill 35‘ 4/ , - 48 . , 3 > 43 m , ' ,3 ‘3,9 25 _ II ,5 @135’. Z Z7 ./7 ‘ —-> 5M6. Pump’ 3 4‘ 90X. PUMP OUT Patented Sept. 3, 1946 2,406,854 ‘ UNITED STATES PATENT OFFICE 2,406,854 MULTIPLE TANK FUEL SYSTEM David Samiran, Osborn, Ohio Application February 12, 1943, Serial No. 475,683 9 Claims. (Cl. 158-364) (Granted under the act of March 3, .1883, as amended April 30, 1928; 370 0. G. 757) 2 The invention described herein may be manu factured and used by or for the Government for Referring to Fig. 2, which shows an enlarged longitudinal cross section through one of the sole noid-operated valves, the ?ow between the inlet governmental purposes, without the payment to me of any royalty thereon. ~ This invention relates to fuel systems and has particular reference to systems employing a plurality of fuel tanks such, for instance, as the system on an aircraft. An object of the invention is to provide a fuel system of this character with means to maintain 1e pressure in the fuel line substantially constant while changing the connection of the suction side of the fuel pump from one tank to the next as successive tanks are emptied. Another object is to provide power-operated means to change the connections of the fuel pump, which extend to the fuel tanks, from an empty to a full tank, with means for automatically sensing the fact of an empty tank and applying the power means for making the change, then disconnecting the power means after the change is made. Another object is to provide manually selective means for quickly connecting to any one of the several tanks, independently of the power means, when that becomes desirable. Other objects and advantages will be readily perceived by a study of the following description with reference to the drawings, wherein: Fig. l is a schematic view of a fuel system made according to my invention; Fig. 2 is an enlarged View of the solenoid-oper- 5 33 which is lifted 'to “open” position by a sole noid core 36, which is in turn lifted by coils 38 and 4G. The coil 38 is wound of relatively coarse wire and few turns, While the coil 40 is wound of ?ner wire, the intention being to apply a heavy 10 current to the coil 38 to lift the valve disk from its seat, then discontinue the heavy current in the coarse wire coil .38 and apply a small current to the ?ne wire coil 49, to thereby hold the valve in “Open” DOSitiOn With a minimum expenditure 0f’ 15 energy- A solenoid-controlled valve, such as is lOWIl in Fig. 2, will be described and claimed in' a Separate application Of which I am joint in Ventor. A fuel discharge pipe 42 extends from the main 20 fuel pump l2 to the bottom of an air separator 44, the outlet pipe 46 of which delivers fuel to the carburetor Id. The pump I2 is of the type having a built-in relief valve such as is shown at 57 in the enlarged View, Fig- 5 being thereby 25 adapted to maintain a given pressure Output, the relief valve in this pump being adjusted to deliver fuel to the outlet at ?fteen pounds pressure. A ?oat 48 in the top of the air separator is so loaded as to permit the discharge of vapor from 30 the top of the separator to the tops of the tanks through a pipe 50 when the amount of accumu lated vapor in the top of the air separator forces ated valves of Fig. 1 shown in detail; ' Fig. 3 is, an enlarged vertical axial section the liquid fuel down to a predetermined level. The air separator is unique in that it is ar through-the air eliminator of Fig. 1; 39 and the outlet 32 is controlled by a valve disk 35 ranged to receive the fuel discharged‘from both Fig. 4 is an enlarged vertical axial section the main pump l2 and an auxiliary pump 52 and through a special check valve of Fig. 1; discharge the fuel free from air through a com Fig. 5 is an enlarged vertical section through mon pipe 46. It is shown in detail to an enlarged either'the main pump or the auxiliary pump of scale in Fig. 3 and comprises an outer vessel Fig. 1; 40 II and a concentric imier vessel 13 secured to Fig. 6 is an axial section through the powergether so as to leave a space l5 between them operated selective switch for operating the solewhich connects with the opening I‘! into which noid valves. the engine-driven fuel pump discharges. A con Similar numerals refer to similar parts centric cone~shaped part I9 is secured at its throughout the drawings. ’ _ Referring now particularly to the schematic illustration Fig- 1, an engine I" Carries a main 45 periphery to the inner vessel 13 and a long tubu lar portion 2| connects to the opening 23 into which an auxiliary fuel pump discharges. The fuel pump E2, the pump being operatively conspace 25 between the vessel I3 and cone l9 con nected to the engine to be rotated thereby, and meets to the outlet opening 21 from which the fuel adapted to supply fuel to a carburetor I 4- A 50 flows to the carburetor through the pipe 46. The manifold it connects the intake side of the fuel ?ange of a ?oat housing 29 is held between a pump [2 to a series of tanks I to 6, inclusive, cover 3| and an intermediate section 33, leaving the‘fuel passing through solenoid-operated valves a space 35 between the float housing and the l8 to 28, which control the flow from the tanks intermediate section. Circular rows of small to the pump. 55 holes 31 and 39 connect the spaces I 5, 25, and 2,406,854 3 35 to each other. The float 48 is guided at the bottom by a tube 4! which fits freely in a hub 43 of the ?oat housing and at the top by a valve needle support (l5 which ?ts freely in a valve seat member 6.1. The valve needle 43 is resiliently held by a spring 5| extending upward from the bottom of the support 45 which is fastened onto the hub 53 on the upper side of the ?oat, whereby the needle is resiliently seated when the float 4 pipe 42 to about twelve pounds. A signal lamp 85 is so connected to the switch terminal 10 as to give warning whenever the switch 15 has reached a “closed” position. A second pressure-sensitive switch, which may be broadly designated by the numeral 8!, com prises a body ‘12 and a contact bar ‘M which is adapted to be moved to connect the contacts 16 and 18. Switch 81 may be supported on the en rises. The sides of the ?oat housing 29 have a 10 gine ill and is connected to the lubricating oil system by a pipe 83, being responsive to the oil plurality of perforations 55. pressure of the engine. The switch 8| is con The auxiliary fuel pump 52 shown to an en structed substantially like the switch 15 with re larged scale in Fig. 5 may be connected to either spect to the diaphragm and the spring, except one of the six tanks by a suction pipe 5%, the that while the application of pressure to the up tank selected. in the instant case, for illustrative per surface of the diaphragm of the switch '15 purposes, being tank 6. A discharge pipe 58 ex opens it, the application of pressure to the upper tends from the outlet of the auxiliary pump to surface of the diaphragm of the switch 8| the bottom of the air separator M, whereby fuel closes it. from the auxiliary pump also passes through the A main manual switch Bi! is provided to con air separator and through pipe I16 to the car 20 nect the battery 82 to the post 84. An additional buretor Me. The auxiliary pump is also of the manually controlled switch 85 connects the switch type having a relief valve 51 which maintains a given pressure output, the relief valve 5‘! in the auxiliary pump being set to deliver fuel under a pressure of ten pounds. An electric motor 58 is provided for operating the auxiliary fuel pump. Since the relief valve 5‘! is set to return fuel from the high to the low pressure side at ten terminal 10 of the switch 15 to the binding post This switch may be used whenever it becomes desirable to stop rotation of the pump motor 58 while the main . 88 of the auxiliary pump motor 58. switch 80 is closed. An automatic power-operated valve selector 9!] (see Figs. 1 and 6) comprises an electric motor 92 pounds pressure, and the engine pump l2 puts fuel into the high-pressure side at ?fteen pounds 30 which may preferably have an inbuilt speed reducing gear box of high ratio so that the shaft pressure, a check valve 59 is provided to prevent 94 may operate at greatly reduced speed——that is, fuel returning from the high pressure side the motor 92 may preferably rotate as much as through the auxiliary pump 52 to the tank 5. two hundred R. P. M. to one B. P. M. of the shaft Check valve 59 shown in detail in Fig. 4 com 94. A dielectric disk 95 is concentrically sup ported on the ?ange 91 of the motor 92, and prises a casing 6| divided into three compart ments—63, 65, 6'!—by two spaced-apart Sylphon carries a circular row of twelve electrical con diaphragms 69, compartment 65 being open at 8‘! tacts, pairs of which are connected to the sole to the atmosphere, whereby, since the atmos noid-operated valves, contact IL being connected pheric pressure acts in opposite directions on the two Sylphons 69, any change in altitude, and its 40 to the lifting coil of valve l8, and contact I being connected to the holding coil of valve [8; contact consequent change in atmospheric pressure, does 2L being connected to the lifting coil of valve 20, not affect operation of the valve. A valve head and contact 2 being connected to the holding coil ‘H has its stem 13 sealed to both diaphragms by of valve 2%; etc. A cam 98 is secured to the shaft nuts 89. Valve head ‘H is biased to “open" posi 54 to rotate in unison therewith. A contact arm tion by the spring 11 which reacts against a par we is loose on the shaft 94 and insulated there tition 19 extending from the casing 6!. Com from by a dielectric bushing 95 but is caused to partment B3 and the space 99 above the relief rotate with the shaft by means of a plunger [02 valve 51 of the auxiliary pump are connected to which is slidable in a dielectric bushing I03 in the pipe 4% by a pipe 9!, whereby the Valve 59 is closed by the pressure in compartment 63 when 50 the end of the arm H30 and has its free end ex tending into one of the six notches I94. A knob m5 is provided, the knob and the arm H10 both being fast on the bushing 95, whereby the con tact arm I09 may be manually rotated in advance of the slow rotation of cam 98 when so desired. ever the discharge pressure of the main pump 12 exceeds the discharge pressure of the auxiliary pump 52 by a predetermined amount, and the spring 99 of the relief valve 51 is assisted in pre venting leakage backwardly through the auxil iary pump by the same pressure while compart ment 61 is connected by a pipe 33 to the pipe 46 through the air separator 44 and to the outlet 56 of the auxiliary pump when the valve 59 is A spring I86 maintains the plunger I02 seated in open. A dielectric plunger I Ii) is carried on a metal arm Connected into the high-pressure side of the two fuel pumps above described, by connecting into the pipe 42, is a fuel-pressure-sensitive elec trical switch which may be broadly designated by the numeral 15. Switch ‘[5 comprises a body 60 divided into two compartments by diaphragm 62 which is moved in one direction by the pressure whichever notch it happens to engage. On the outside of cam 98 are a series of six cam lobes I08 equally spaced around its periphery. H2 which is hinged at HG to the dielectric disk 96, the free end of this arm being adapted to en gage an extension of the binding post H6 of the motor 92. A coil spring H8 urges the arm H2 " toward engagement with the binding post exten sion. The point of contact between the arm H2 and the extension of the binding post H6 serves in the pipe 42, but urged in the opposite direction by a spring 64 whereby, in the absence of suf? cient pressure in the pipe 42, the spring 64 moves a contact bar 65 into engagement with contacts 68 and ‘H1, thereby keeping switch 15 closed as shown in Fig. 1 until the pressure in pipe 42 is restored. The spring 64 is so proportioned that switch 15 closes upon a drop in pressure in the 75 as a switch which may be hereinafter referred to as the switch I29. Electrical conductors connect the post 84 to the terminal 68 of switch 15, the terminal ‘E0 to its signal light 35, the terminal 70 to the terminal 16, the terminal 18 to the bind ing 'post i IS, the terminal ‘l'il through the switch 86 to the binding post 88, and the post 84 to the arm H2 and the contact arm I09. I 2,406,854, 5 6 ' ITheoperation of the mechanism is as follows; If the engine is at rest and no fuel pumps are 92‘from the‘ ignition post through both switches ‘I5 and BI, the arm could readily stop rotating in operation, the reduced pressure in the body 50 before it had reached a proper position for hold of the switch ‘I5 will have permitted the switch to ing open the valve 20 of tank 2, since the fuel beclosed as shown, while absence of oil pressure 5 pump I2 might readily- have built up a pressure in the engine. I0 will have permitted the switch of twelve pounds and opened the switch ‘I5 in 8| to beopened as shown. In order to start the advance of a complete movement of the arm I00 ~ engine, the main switch 80. and the manual switch through 60 degrees to its next succeeding posi 86 should now be closed. This will supply current tion. With the arrangement shown, when a tank to the binding post 88 of the auxiliary pump mo 10 from which fuel is being pumped becomes empty tor 58. Rotation of the auxiliary pump 52 will and air passes through the pump I2, resulting in nowbuild up a pressure of ten pounds in the car a drop in pressure on the diaphragm 62, and the . buretor I4, which is enough to start the engine valve ‘I5 thereby closes and starts rotation of the The building up of the pressure in this manner arm I00, rotation may not cease until the arm should be accomplished before there is any at 15 has traveled through one-sixth of a revolution, tempt to start the engine. The ten-pound pres even though pump I2 may build up sumcient sure supplied ‘to the carburetor I4 will not, how pressure to open the switch ‘I5 ‘before the one ever, operate the switch ‘I5 tof‘open” position, in- ‘ sixth revolution has been completed. It should asmuch as this switch is setto open at twelve be kept in mind also that the auxiliary pump 52 pounds. As soon, however, as the engine starts, 20 continues to supply fuel under a pressure of ten thepump I2, which is set to deliver fuel at ?fteen pounds pressure and which is driven by the en gine, will operate the switch ‘I5 to “open” posi tion, while the oil pressure built up by the engine pounds up to the instant that the engine-driven , pump I2 builds up its pressure to twelve pounds and opens the switch ‘I5, which insures a satis factory fuel pressure during the entire time that will operate thepswitch ill to its “closed” position. 25 a change-over from an empty to a full tank takes As soon as this occurs, current will be cut off from place. the auxiliary pump motor 58, and the duty of When the next succeeding lobe I08 has raised supplying a ?fteen-pound pressure to the car the lobe He and opened the switch I20, the arm buretor I4 will be assumed by the pump I2, the I00 will have passed the contact 2L by which the ‘ check valve 59 becoming operative to prevent 30 valve 20 was opened and will now be resting only fluid from the pump I2 being pumped in reverse on the contact 2 by which the valve 20 will be direction through the relief valve 51 of the aux held open. The width of the arm I00 and the iliary pump 52, and the relief valve 51 being re size and spacing of the contacts, however, should inforced'against leakage by virtue of the ?fteen be such that the arm engages the contact 2 pound pressure being applied in the space above 35 slightly before it leaves the contact 2L, for other the relief valve to hold it closed. wise the valve would close as soon as the arm left Thus far no electric current has as yet been ' the contact‘ 2L. When change in connection has delivered to the binding post II6 of the valve thus been made between an empty tank I and a selector motor 92, inasmuch as the switch ‘I5 and full tank 2, no further changes will take place the switch 8| have not thus far been closed at 40 until tank 2 becomes empty. If, however, tank the same time; neither has current been delivered 2 when thus connected was found to be already‘ to the binding post IIB through the arm II2, empty, the selector merely passes over it, since since this occurs only when the spring [I8 effects air drawn from empty tank 2 and transferred to contact of the arm with the binding post, which pipe 42 would close the switch ‘I5 and move the may not occur until the lobe I08 of the cam moves arm I00 forward to connect the tank 3. Thus from under the lobe I III of the arm. The contact the automatic selector will search the entire series arm I00, therefore, up to this time, has main— of tanks and will not stop until a full one is found, tained the valve I8 in its “open” position and the auxiliary pump meanwhile maintaining a will continue to so maintain it until current is satisfactory fuel pressure until a full tank is in some manner supplied to the binding post I I6. 50. found. Such an arrangement is desirable be 1 When the engine has been in operation for a cause it may sometimes happen, particularly sufficient time to empty the tank I, the pump I2 where the system is used on war craft, that one will momentarily draw air from the empty ‘tank of the tanks will have been punctured and the I and pump it into the pipe 42, which will in fuel lost, in which case it becomes necessary that stantly cause the pressure in the discharge pipe 55 the selector operate to pass such tank and con 42 to drop. ' When it‘ has dropped to as little as nect the system to one that is full. As an added twelve pounds, which will be almost instantly, measure of safety, I may provide a multiple hand the switch ‘I5 will close, while the previously operated fuel valve I22 by which any one of the closed switch 8| remains closed, the air drawn in tanks may be connected to the pump I2 should by pump I2 passing out through the air separator automatic operation of the selector valve fail. 44.’ When both switches ‘I5 and 8| are closed, The need for using this 'manual valve would ap current will ?ow to the binding post I I6, and the pear upon an extended signal from the light 85. selector motor 92 will begin rotating the cam 98 I claim; ‘ ' clockwise, carrying the contact arm I00 with it. 1. The combination, in an aircraft fuel system, As soon as the cam 98 rotates slightly, the lobe 65 of an engine, a main fuel pump driven by said I08 moves from under the lobe I I0 and the spring engine, .a plurality of fuel tanks each connected II8 closes the switch I20, after which current to the suction side of said pump, an electromag will be supplied to the binding ‘post Il6 directly netically operated valve interposed in each of the from the post 84 until the next succeeding lobe I08 moves under the lobe IIO, thereby opening the switch I20 and stopping the arm I00 at the desired place. The above arrangement is highly desirable, for lines which connect a tank to the pump, a sole ,noid for holding the valve open, a carburetor con nected to the discharge side of said pump, an auxiliary fuel pump having its suction side con— nected to one of said tanks independently of the while the arm I00 would continue rotation as electromagnetically operated valve and having long as current wasbeing supplied to the motor 75 its discharge line connected to the discharge side 2,406,854 7 of said main pump, a check valve in said dis charge line biased to prevent ?ow from the dis charge side of the main fuel pump to the dis? charge side of the auxiliary fuel pump, an electric pump being adapted to deliver fuel at a higher pressure than the auxiliary fuel pump, a check valve adapted to. prevent flow from the discharge side of said main fuel pump to the discharge side motor for driving said auxiliary fuel pump, an 5 of said auxiliary fuel pump, a pressure responsive switch associated with the main fuel pump, electric current source, a switch for connecting adapted, upon a predetermined drop in pressure said electric motor to said source, a pressure op at the discharge side of the main fuel pump, due erated means connected to the discharge side of to a receptacle to which its suction side is con said main fuel pump for holding said switch open nected being empty, to close and direct an elec by said discharge pressure, a rotatable switch tric current to operate said electric motor driven having circumferentially spaced insulated cur auxiliary fuel pump, and electromagnetic means rent supplying contacts for directing current to the coils of the electromagnetically operated operative by said switch, upon closing, to discon valves, an electric motor for rotating said rotat able switch, a cam rotatable by said motor, said nect the suction side of the main fuel pump from the empty receptacle and connect it to a full re ceptacle, whereby said main fuel pump may pro vide said predetermined pressure to open said pressure operated switch to stop said electric mo cam having a series of lobes and a series of de tent notches, each corresponding to the number of electrically operated valves, a cam operated switch, successively operable to open position by each of said lobes upon rotation of said cam, a tor driven auxiliary pump. 4. The combination, in an aircraft fuel system, of a main fuel supply receptacle, a main fuel pump having its suction side connected to said main fuel supply receptacle, a reserve fuel supply container, an auxiliary fuel pump having its suc said detent notches, said ‘notches and said lobes being so spaced on said cam that when the arm 25 tion side connected to said reserve fuel supply container, a fuel receiving means, the discharge engages a valve holding solenoid contact, the cam side of both said pumps being connected to said operated switch is open, electrically conductive current supplying arm rotatable about the axis of said cam, a detent member carried by said arm for resiliently engaging in any selected one of fuel receiving means, and a fuel pressure respon means for connecting the current source in paral sive means associated with the main fuel pump, lel through the fuel pressure operated switch and through the cam operated switch to the rotatable 30 adapted, upon a predetermined drop in pressure switch electric motor, electrically conductive means for connecting the current source to the arm of the rotatable switch, and electrically con ductive means for connecting the current source through the fuel pressure operated switch to the at the discharge side of the main fuel pump to operate said auxiliary fuel pump. 5. The combination, in an aircraft fuel sys tem, of a main fuel supply receptacle, a main fuel pump having its suction side connected to said main fuel supply receptacle, a reserve fuel sup auxiliary pump motor. ply container, an auxiliary fuel pump having its 2. The combination, in an aircraft fuel system, suction side connected to said reserve fuel supply of a plurality of main fuel supply tanks, a main container, a fuel receiving means, the discharge engine driven fuel pump, valves operable to con— nect the suction side of said pump to either of 40 side of both said pumps being connected to said said main fuel supply tanks, a reserve fuel supply container, an electric motor driven auxiliary fuel pump having its suction side connected to said re serve fuel supply container, a fuel receiving means, the discharge side of both said pumps fuel receiving means, and a pressure responsive means associated with the main fuel pump, adapted, upon a drop in pressure at the discharge side of the main fuel pump to a pressure slightly above the discharge pressure capacity of the aux iliary fuel pump to operate said auxiliary fuel being connected to said fuel receiving means, and pump, whereby restoration of the discharge pres the main fuel pump being adapted to deliver fuel sure of the main fuel pump is required to stop at a higher pressure than the auxiliary fuel pump, the auxiliary fuel pump. a check valve adapted to prevent flow from the discharge side of said main fuel pump to the dis 50 6. The combination, in an aircraft fuel system, of a main fuel supply receptacle, a. main fuel charge side of said auxiliary fuel pump, a pres pump having its suction side connected to said sure responsive switch associated with the main main fuel supply receptacle, a reserve fuel supply fuel pump, adapted, upon a predetermined drop container, an auxiliary fuel pump having its suc in pressure at the discharge side of the main fuel pump, due to a tank to which its suction side is 55 tion side connected to said reserve fuel supply container, a fuel receiving means, the discharge connected being empty, to close and direct an side of both said pumps being connected to said electric current to operate said electric motor fuel receiving means, each pump being adapted driven auxiliary fuel pump, and electromagnetic to maintain a predetermined discharge pressure, valve operating means operative by said switch upon closing to close the valve of the empty tank 60 the predetermined discharge pressure of the main pump being higher than that of the auxiliary and open the valve of the next full tank, where pump, and a pressure responsive means associ by said main fuel pump may provide said prede ated with the main fuel pump, adapted, upon a termined pressure to open said pressure operated predetermined drop at the discharge side of the switch to stop said electric motor driven auxiliary 65 main fuel pump to a pressure between the dis pump. charge pressures of the two said pumps to operate 3. The combination, in an aircraft fuel system, said auxiliary fuel pump, whereby restoration of of a plurality of main fuel-supply receptacles, a the main pump to its predetermined pressure main fuel pump having its suction side connected capacity will stop operation of the auxiliary to either of said receptacles, a reserve fuel-sup pump. ply container, an electric motor driven auxiliary '7. The combination, in an aircraft fuel system, fuel pump having its suction side connected to of an engine, a main .fuel supply receptacle, an said contaainer, a fuel receiving means, the dis engine driven fuel pump having its suction side charge side of both said pumps being connected connected to said main fuel, supply receptacle, to said fuel receiving means, and the main fuel 75 a reserve fuel supply container, an electrically 2,406,854 driven fuel pump having its suction side con nected to said reserve fuel supply container, a fuel receiving means, the discharge side of both said pumps being connected to said fuel receiv ing means, each pump being adapted to main tain a predetermined discharge pressure, the pre determined discharge pressure of the engine driv en pump being higher than that of the electri 10 - which is between the discharge pressures of the two pumps to operate said electrically driven pump, and a check valve interposed between the discharge sides of the two pumps biased to pre vent ?ow from the discharge side of the engine driven pump to the discharge side of the electri cally driven pump. ' 9. The combination, in an aircraft fuel system, cally driven pump, and a pressure responsive of an engine, a plurality of main fuel supply re electric switch associated with the main fuel 10 ceptacles, an engine driven pump having its suc pump, adapted, upon a predetermined drop at tion side connected to either of said main fuel the discharge side of the main fuel pump to a supply receptacles, a reserve fuel supply con pressure between the discharge pressures of the tainer, an electrically driven pump having its, two said pumps to operate said auxiliary fuel suction sideconnected to said reserve fuel supply pump, whereby restoration of the engine driven container, a fuel receiving means, the discharge pump to its predetermined pressure capacity will 15 sides of both pumps being connected to said fuel stop operation of the electrically driven pump. receiving means, the engine driven pump being 8. The combination, in an aircraft fuel system, arranged to maintain a given discharge pressure of an engine, a main fuel supply receptacle, an and the electrically driven pump being arranged engine driven fuel pump having its suction side 20 to maintain a lower discharge pressure than connected to said main fuel supply receptacle, the engine driven pump, a pressure responsive a reserve fuel supply container, an electrically electric switch connected to the discharge side driven fuel pump having its suction side ‘connect of the engine driven pump, adapted upon a drop ed to said reserve fuel supply container, a fuel at the discharge side of the engine driven pump, receiving means, the discharge side of both said 25 to a pressure which is between the discharge pumps being connected to said fuel receiving pressures of the two said pumps, to operate said means, the engine driven pump being arranged electrically driven pump and electromagnetic to maintain a predetermined discharge pressure means operative coincidentally with said pressure and the electrically driven pump being arranged responsive electric switch to disconnect one main to maintain a lesser discharge pressure than the 30 fuel supply’ receptacle from the suction side of engine driven pump, a pressure responsive elec the engine driven pump and connect another tric switch connected to the discharge side of the main fuel supply receptacle thereto. main fuel pump, adapted, upon a drop at the dis charge side of the main fuel pump to a pressure I DAVID SAMlRAN.