Oct. 15, 1946. F. M. LEWIS , 2,409,218 STRAIN RELIEVING AND DEPHASING STOP MEANS FOR FREE PISTON ENGINES Filed Dec. 26, 1944‘ NW $343 4 sheets-sheet 1 __~ m‘ Get. 15, 1946., F. M. LEWIS _ 2,409,218 STRAIN RELIEVING AND DEPHASING STOP MEANS FOR FREE PISTON ENGINES Filed Dec. 26, 1944 4 Sheéts-Sheet 2 gnaw/bow @o-uycq W, I Oct. 15, 1946. F. M. LEWiS 2,409,218 "TRAIN RFJZIIEVINGv AND DEPHASING STOP MEANS FOR FREE PISTON ENGINES _ Filed Déc. 26, 1944 r ' _4 Sheets-Sheet s 20 Hi 95 95 97* 94 gnaw/WM THANK MLEWJB _ I 3343 @ae/m?' @0444,‘ ‘ Oct. 15, 1946. F. M. LEWIS 2,409,218 STRAIN RELIEVING AND DEPHASING STOP MEANS FOR FREE PISTON‘ Filed Dec: 26, 1944 ENGINES 4 Sheets~$heet 4 Patented on. 15, 1946 2,409,218 UNITED STATES PATENT OFFICE 2,409,218 'STRMN IRELIEVING AND 'DEPHASING STOP MEANS FOR FREE PISTON ENGINES Frank M. "Lewis, ‘Weston, Massg assignor to Gen eral Machinery Gorporation, Hamilton, Ohio, a corporation of Delaware Application December 26, 1944, Serial No. 569,871 22 Claims. 1 2 This invention relates to internal combustion engines of the free piston type, and particularly to means in connection therewith for stopping the operation of the engine when a dephased or rack-bars broken away, and including certain‘op crating features of the invention; Fig. 3 is__a cross~section thereof on the line 3—3 in Fig. 2; Fig. 4 is a central longitudinal section thereof unsynchronized running of the engine pistons on the line 4—-4 in Fig. 2; Fig. ‘5 is an end view develops. of the device shown in Fig. 2-, with one of the In an operation of ‘such engines, the so-called rack-Hears in section; Fig, 6 is an e'nlargedsec free pistons comprise two opposing piston sets tional detail of one of the fluid pressure line con which move outward under the force of an ig trol valves associated with the means shown in nited fuel charge injected therebetween and mov- 10 Fig. 2; Fig. 7 is a longitudinal sectional‘deta-il of ing inward under direct bounce action of comthe trip control ‘means for the fuel feed ‘pump; pressed gases to compress and ignite the next Fig. 8 is a sectional view of a conventional form fuel charge. The opposing pistons are connected of fuel pump; Fig. 9 is a modi?ed form of the ‘in in a manner to cause a proper synchronizing of vention embodying a valve in the fuel injection their movements, and in operation of the engine 15 line from the pump to the engine, which valve it is common occurrence for the parts of the is moved bya predetermined dephasing action of synchronizing means to be harmfully stressed ‘due the pistons to relieve injection pressure in such to the sticking or dragging of one of the piston line; Fig. 10 is a fragmentary detail of such mod sets, which creates a dephasing condition of the‘ i?cation; Fig. 11 is another modi?cation‘ of the piston movements, 20 invention embodying an electrical control feature The object of the present invention is the provision of simple and efficient means in connection with, and automatically operable by, the piston for the fuel feed shut-off; Figs. 12 and 13 are fragmentary details thereof, and Fig. 14 is a mod i?cation of the electrical control means shown in synchronizing means of an engine of this char- Fig. 111. actel" to interrupt the engine Operation when a 25 endency arises for the pistons to become dephased or unsynchronized in their motions due to either set of pistons sticking or dragging in Referring to the ‘drawings, 1 designates an in ternal combustion engine of the free piston type having opposed piston sets, each com-prising a working piston 2 operating in a combustion its action, or to other causes. chamber 3, an air compressor piston 4 operating A further object of the invention is the provi- 30 in a chamber 5, and a direct bounce piston 6 cp sion of means for governing the automatic stopcrating in a chamber 1, all for the purpose and ping action of the engine upon a dephasing 0011- dition of the pistons occurring, whereby the stopping means will be brought into effective action only by a predetermined magnitude of the dephasing stressess. Another object of the invention is the provision of simple and efhcient means of a cushion nature forming a part of the piston synchronizing means of free piston engines t0 absorb and materially reduce engine shock loads, especially when the shocks are due to unequal loading, and therefore to offer a certain amount of resiliency to the engine. Further objects and advantages of the invention will be apparent from the following detailed description, and from the accompanying drawings illustrating one embodiment thereof, and in which— Figure l is adiagrammatic View of a free piston engine equipped with means embodying the invention, with the pistons at substantially the limit of their outward strokes; Fig. 2 is an outer side elevation, partly in longitudinal section, of the synchronizing means for the pistons, with the in a manner well understood in the art. The two piston sets are connected by suitable means to cause them to operate in proper syn‘ 35 chronized relation. In the present instance, this means includes a rackebar 8 projecting inwardly from one piston 4 and a rack-bar 9 projecting ‘in wardly ffom the other piston 4 through the inner end wall of the respective cylinder 5, with the 4-0 bars in laterally ‘spaced parallel relation at a side of the cylinder I0 forming the combustion cham her 3. A pinion ll (Fig. 2) is interposed be tween the rack-bars, in mesh with each, and has trunnions i2 journaled in a carriage [block I3 for 45 ?oating movements therewith lengthwise of said rack-bars, for the purpose and as hereinafter more fully described; The engine is equipped with a fuel injection pump [5 which is conventionally shown in the 50 drawings (Fig, 8) as including a charge cham ber l6 receiving its fuel oil supply from a con stant pressure supply pump 52 through a pipe line 59, 5| and having its discharge to the asso ciated fuel injection nozzle IQ of the engine 55 through the line 20. A plunger .2! is reciproi 2,409,213 3 cably movable in the pump casing to force a fuel charge from chamber IE to the nozzle, and is rotatable about its longitudinal axis whereby a controlled metered charge of fuel is admitted to the charge chamber from the pipe 56 during one stroke of the plunger and is ejected therefrom to the fuel nozzle during another stroke thereof. Rotary adjustment of the plunger to vary the 4 with a supply line 5| leading through a pressure pump 52 from a tank, or other suitable supply source 53. Each branch line 49, 56, has a normally closed valve 55 therein. Each of such valves includes a casing 56 (Fig. 6) preferably secured for length wise adjustment’to a convenient part of the en gine frame by screws 51 projected through slots 58 in the casing. A valve stem 59 operates in the fuel feed is e?ected by longitudinal movement of a rack-bar 22 in engagement with a pinion 23 10 casing with one end projected therefrom and is adapted, when in one position, to close a cross on the plunger, as is common in the art. In passage 66 in the casing which forms a part of the present instance, the fuel charge is increased the respective branch line 49, 56 in which the when the rack-bar 22 is moved to the left and valve 55 is disposed. The valve stem has a recess is reduced when the bar is moved to the right. 6| disposed in position to register with the cross The plunger 2| carries a roller on its outer end passage 66 and open the respective branch line which travels on a side edge of the rack-bar 9, when the stem is moved inward a slight extent in the present instance, and is actuated to cause from its outward position. A spring 62 acts on the plunger to eject a fuel charge at a prede the valve stem to normally hold it in closed-posi termined point in an engine cycle by engagement of the roller with a cam 25 on said rack-bar. This engagement is customarily timed to take place just before the working pistons have reached the ends of their inward‘ or compression strokes. A control for the pump rack-bar 22 to impart reciprocatory movements thereto to increase or reduce the fuel feed charge to the injection nozzle |9 includes a rod 36 (Fig. 7) connected to or forming a, continuation of the left end, in the present instance, of the pump rack-bar 22. This rod projects at its opposite end into the open end tion. ‘ The carriage |3 for the pinion II is in the nature of a cross-head and is guided for move ments longitudinally of the engine | by upper and lower guides 65 provided in the attachment 66 secured to the side of the engine cylinder ID by screws 67. The rack-bars 8 and 9 of the piston synchronizing means are also guided for recipro catory movements in the attachment 65 and are held thereby in meshing engagement with the 30 pinion II at opposite sides of its axis. The car ~riage i3 is yieldingly held in central or neutral of a cylinder 3| where it connects to a hollow position by a spring pressed pad 68 at each end open ended plunger 32 which is reciprocally mounted in a trip sleeve 33 that is slidingly mounted in the cylinder 3|. A compression spring 34 is disposed in the hollow of the mem bers 32 and 33 between the opposed closed ends its spring ‘H are carried by a cup 12 at the re spective end of the carriage. The screw 69 may engaging an adjustable screw 69 in an end por tion it! of the attachment 66, Each pad 68 and be locked in adjusted position by a lock nut 13. A valve opening rod 15 is mounted in each part thereof and exerts an outward moving force on '10 in line with the movement of the carriage I3 the rod 30 to move the rack-bar 22 tothe right or in fuel feed reducing direction. The move 40 and normally slightly spaced therefrom, so that upon a predetermined movement of the carriage ment of the trip sleeve 33 to the left is opposed by a compression spring 35 in the closed or left end of the cylinder 3 I. A block 36 is slidingly mounted on the rod 30 in either direction from neutral position, it will strike one or the other of the rods 15 and, upon a continuation of such movement, move it out ward against the tension of a spring 16. Such spring, in the present instance, acts at one end against a stop collar 11 which is adjustable on the rod to vary the normal spacing 18 between its inner end and the carriage. Each rod 15 pro apart. Movement is imparted to the block 36 jects at its outer end from its mounting part 16 lengthwise of the rod 36 by a lever 36 which is in longitudinal register with the stem 59 of the fulcrumed to the engine frame at 39 (Fig. l) respective valve 55 and in position for an out and has one end in sliding pivotal connection ward movement of the rod from normal position with the block and its other end connected by a to move the valve stem to open position. link 46 to a manually operable control lever 4|. In the operation of this feed control, it is set This lever is retained in adjusted position by re by an adjustment of the hand lever 4| for desired leasable engagement of a hand latch thereon running conditions. In effecting such adjust with a ratchet sector 42. The spring 31 opposes ment, the block 36 is moved to the right or left the pressure of the spring 34, being normally of on the feed control rod 36, its movement to the greater tension, and the spring 35 opposes and is 60 right permitting a reduction in the fuel feed and of greater tension than both springs 34 and 31. its movement to the left effecting a tensioning The trip sleeve 33 is held in retracted position, of the spring 31 and causing a movement of the with the spring 35 compressed, by a trip pin 43 control rod to the left to increase the fuel feed operating through a side aperture in the cylinder until the tension of the spring 3'! is equalized with 3| and engaging at its inner end in an annular recess 44 in the circumference of the sleeve. 65 that of the opposing spring 34. It will be under stood that during such adjustment of the fuel The outer end of this pin is attached to a piston feed the trip sleeve 33 is retracted and held in 45 in a cylinder 46 mounted on the cylinder 3|. such position by the trip pin 43 against the ten A spring 41 applies an inward force to the piston sion of the spring 35. During normal operation to yieldingly hold the pin in looking engagement within the recess 44 of the trip sleeve 33, and 70 of the engine it functions on the two-stroke cycle principle, so that the cam 25 on the rack-bar 9 fluid pressure is admitted through a pipe line 48 of the engine piston synchronizing means engages to the cylinder at the inner side of the piston to the roller on the pump plunger and actuates the move it outward to cause the pin to release the pump to inject a fuel charge into the combus trip sleeve. The line 48, in the present instance, has connection through two branches 49 and 56 75 tion chamber of the engine each time the pis in spaced relation to the plunger 32 and a com pression spring 31 is mounted on the rod be tween the block and plunger in end-thrust en gagement with each and tends to move them 5 2,409,218" tons are substantially at the ends of their inner charge compressing movements. However, should either ‘of the engine pistons fail to function prop erly, thereby throwing an'undue stress upon the rack-bars 8 and 9, or on the coacting pinion H, pin, designated 43*‘ in Fig. 13, is held yieldingly engaged with the trip sleeve 33 by a spring lil'5L and is released from’ the sleeve by the energizing of a solenoid 90 associated therewith. One end of the solenoid coil is grounded through a lead 9| while the pinion carriage it will move in the direction its ‘ other end is connected, through a control of the applied stress, If such movement is of switch 92 and leads 93 and 94, to an electric cur su?icient magnitude for the carriage to traverse rent supply source 95; This switch, in the present the space 78 between it and the pin 15 toward instance, includes a frame 96 attached to the en which it is moving and to move such pin to push 10 gine frame and having two spaced contacts 91, 91, valve rod 59 to open the coacting valve 55, the Which are in connection with the positive side of respective branch pressure line 49, 55 will be the solenoid coil through the lead 93. These con opened to the cylinder 46, thus instantly admit tacts are in normal predetermined spaced rela ting pressure thereto to move the trip pin 43 tion and each is permitted to move outward from outward to release the trip sleeve 33. Upon such 15 such position against the tension of a spring 98. release taking place, the sleeve 33 will be quickly In the space between the two contacts 91 are moved to the right by the action of the spring mounted two ?oating contacts 99, 99, each carried 35 and will act through the spring 34 on the con by a respective oscillatory spring ?nger I90, and trol rod 39 to move the pump-rack 22 the full normally held thereby in spaced relation both to extent to the right and shut off the pump fuel each other and to the contacts 97. The contacts supply. The amount of effort required to cause 99 are connected by lead 94 to a battery or other the carriage 13 to shift from neutral position is suitable current supply source 55. A ?nger llll determined by the adjusting screw 69 acting projects from the carriage block I 3 between the against the carriage springs ‘H. The adjustment two contacts 99, and upon a predetermined move of the space 78 to determine the magnitude of ment of the carriage in either direction from neu movement of the carriage before one or the other tral will move one or the other of said contacts, of the pressure control valves 55 is opened is depending on the direction of movement of the obtained by an adjustment of the stop collar ll’ carriage, into engagement with the companion on the control pin 15. An adjustment of the contact 91, thus closing the solenoid circuit to clearance spaces 18 may be compensated for by 30 effect a release of the trip pin. moving the entire valve unit '55 relative to- its If desired, the control for the rack bar 22 of mounting screws El, thus maintaining proper the fuel pump I5 may have its “off” movement relationship between the valve stem so and the electrically actuated instead of utilizing electrical rod ‘:5. means to release the trip pin 63a to permit quick ' In the modi?cation shown in Figs. 9 and 10, a 35 movement of the sleeve 33 to move the rack bar to relief valve 80 for the fuel injection pressure is oif position. This is illustrated in Fig. 14 wherein provided in the fuel injection line 28 and is actu the pump rack bar 22 is yieldingly connected at ated upon predetermined movement of the pinion one end to a manual control 33% and at its other carriage block !3 in either direction, through an end to a solenoid M5, the core H16 of which is at interposed lever 8!, to relieve the pressure in tached to the rack bar while its coil l 01 is inter such line and cause a stopping of the engine. posed in the line 93, 9| in place of the solenoid The relief valve 8i‘), in the present instance. 98. It is apparent that when the solenoid I05 includes a casing 82 mounted on the tube 20 and is energized the rack bar 22 is quickly moved to having a pressure relief passage 83 at each of two o? position. opposite sides of the tube and in communication It is apparent that in the operation of the en therewith. Each of such passages is normally gine, full manual control is maintained over the closed by a respective valve 84, the stem 85 of quantity of oil injected by the fuel pump with which projects outward from the tube through out interfering with the automatic action of the a guide opening in the casing 32 and is acted on dephasing actuated stop means to shut off the by a spring 86 to normally hold the valve in fuel feed and stop the operation of the engine re closed position. The stems are radially opposed gardless of the governor or manualcontrol set relative to the tube axis and an inward move tings, and also that the automatic stopping means ment of either will move its valve inward to un will be brought intoeifective action only by a pre cover the respective relief passage 83 to the tube determined magnitude of the dephasing stresses. passage, thus releasing the fuel injection pres- i Inasmuch as the cushioning feature of the pis sure in the tube, ton synchronizing means is itself novel and is The lever 8! is fulcrumed to one of the carriage usable alone to absorb and, reduce the shock loads block guide parts 66 and has one end forked and of engines, especially when shocks are due to un slidingly straddling a pin 81 on the carriage block equal loading, and also for use in connection with l3 and its other end provided withtwo spaced 60 or to correct other operating features of the en arms 88 which span the valve 88, and each carries gine than the dephasing stop means herein de an adjusting screw 89 for engagement with the outer end of a respective valve stem 85 to open its valve upon a predetermined movement of the lever. When the carriage block I3 is in neutral position, each screw 89 is spaced a predetermined distance from its valve stem so that a relief valve is not opened until the carriage block has moved a predetermined distance in either direction from neutral. In the modi?cation shown in Figs. 11, 12 and 13, an electrically operated trip for the trip sleeve‘ 33 of the fuel feed_control is substituted for the scribed, it is separately claimed. The ?oating feature of the pinion in the piston synchronizing mechanism is disclosed but not speci?cally claimed in a co-pending application Serial No. 558,360. ‘ . I wish it understood that my invention is not limited to any speci?c construction, arrangement or form of the parts, as it is capable of numerous. modi?cations and changes without departing from the spirit of the claims. Having thus described my invention, what. I claim as new, and desire to secure by United hydraulically operated trip pin 43 of the means States Letters Patent, is: shown in Fig. 7. In the present form, the trip 75 1. In an internal combustion free piston en-,, 2,409,218 7 8 with i a fuel feed control means for the engine, gine having a piston synchronizing means includ meansfor actuating said control means to reduce the fuel feed, and means operable by predeter mined movements of said mounting means from neutralposition to render said last named means ing a rack-bar projecting inwardly from and mov able with each of the opposing free pistons, and pinion means-connecting and rotatable by oppos ing movements of the rack-bars, a carriage form ing a mount for the ‘pinion means and mounted active. for reciprocatory movements lengthwise of the rack-bar movements, and means normally hold gine having piston synchronizing means, movable ing said carriage in a predetermined neutral po sition and yieldable to relieve load shocks and pis ton dephasing strains on the pinion means. 2. In an internal combustion free piston en * 8. ‘In an internal combustion free piston en means mounting a part of said synchronizing 10 means, ‘and means yieldingly holding said mount gine having a piston synchronizing means includ ing a pinion having connection with and recipro cally rotatable by inward and outward move ments of the pistons, means carrying said pinion and movable lengthwise of the piston movements and operable to yieldingly hold the pinion with its axis in predetermined centered relation to the piston movements, whereby to compensate for load shocks and dephasing strains on the syn chronizing means. 3. In an internal combustion free piston engine having a piston synchronizing means including a ing means in a neutral piston synchronized posi tion-and permitting movement thereof from such position to relieve load shock or piston dephasing strains on the synchronizing means, together with a fuel feed means for the engine, and means operable to quickly move at least a part of said means to impart a predetermined fuel feed con trol movement thereto upon movement of said mounting means a predetermined extent from neutral. 9. In an internal combustion free piston engine having piston synchronizing means, movable means mounting a part. of said synchronizing means, and means yieldingly holding said mount ing means in a neutral piston synchronized posi rack-bar projecting inward and movable with 25 tion and permitting movement thereof from such each of opposing free pistons, and a pinion con position to relieveload shock or piston dephasing necting the rack-bars and tending to cause them strains on the synchronizing means, together with to operate in synchronizing relation, a mountro a fuel feed control means for the engine, trip tatably carrying said pinion and reciprocally means automatically operable when released to movable lengthwise of the rack-bar movements, 30 and means yieldingly holding the mount in a predetermined position of its movement whereby it may move from such position to relieve load shock or piston dephasing strains on the syn chronizing means. 4. Inan internal combustion free piston engine having a piston synchronizing means including a, rack-bar projecting inward and movable with each ‘of opposing free pistons, and a pinion con necting the rack-bars and tending to cause them to operate in synchronizing relation, a mount ro tatably carrying said pinion and reciprocally movable lengthwise of the rack-bar movements, and a cushion acting on said mount at each end and tending to yieldingly hold it in a neutral posi- . tion and to yield under load shock or piston de phasing strains on the synchronizing means. 5. In an internal combustion free piston engine move at least a part of said control means to impart a predetermined fuel feed control move ment thereto, and means operable by said mount ing means when moved a, predetermined extent from neutral to effect a release of said trip means. '10. In an internal combustion free piston en gine having a periodically operable fuel charge means and a, piston synchronizing means, the latter including a rack-bar projecting inward from each piston and pinion means in meshing connection with said bars, a carriage for the pinion means mounted for yielding movements in either direction from neutral lengthwise of said rack-bars, control means for said fuel charge means operable to vary the fuel charge volume thereof, and means automatically operable by predetermined movement of said carriage from neutral upon occurrence of a dephased piston having piston synchronizing means, movable condition to render the pump inoperative. neutral position and permitting yielding move ments thereof to absorb load shocks and piston a control for said last means, means normally 11. In an internal combustion engine of the means mounting a part of said synchronizing 50 free piston type having fuel injection means, rack means, and means yieldingly holding said mounte barsprojecting inwardly from the pistons in lap ing means in a neutral piston synchronized posi ping relation and a synchronizing pinion inter tion and permitting movement thereoffrom such posedbetween the bars in connection therewith, position to relieve load shock or piston‘dephasing means carrying the pinion for movements length strains on the synchronizing means. wise of the rack-bars when a dephased piston con 6. In an internal combustion ‘engine of the dition is present and for normally holding the free piston type having a piston synchronizing pinion in a neutral position, and means operable means including reciprocally movable rack-bars, by predetermined movements of the pinion car a connecting pinion means, and a shaft for the rying means from neutral position to render the pinion means, means forming a guideway length fuel injection means inoperable to inject fuel wise of said rack-bar movements, a carriage charges into the engine. guided for movements in said guideway and form 12.‘ In an internal combustion free piston engine ing a mount for said shaft, and cushion means for having a piston synchronizing means including a said carriage tending to hold it and the shaft in a rotatable pinion, and fuel charge feeding means, movable to actuate said control to reduce the fuel charges a predetermined extent; trip means oper ableto hold said last means against normal move having piston‘ synchronizing means; movable means mounting a part of said synchronizing 70 ment, a carriage carrying said pinion and mount ed for reciprocatory movements transverse to the means, and means yieldingly holding said mount pinion axis and lengthwiseof the engine piston ing means in a, neutral piston synchronized posi movements, means yieldingly resisting movement tion and permitting movementthereof from such of the carriage from a neutral pinion position, position to relieve load shock or. piston dephasing and means rendered operative by a predetermined 75 strains on the synchronizing. means, together dephasing strains on the synchronizing means. '7. In an internal combustion free piston engine 9 2,409,218 movement of the carriage from neutral position to release said trip means. 13. An arrangement as called for in claim 12 wherein the means which is operable to release the trip means is of a hydraulic nature. 14. An arrangement as called for in claim 12 wherein the means which is operable to release the trip includes a hydraulic pressure line, a nor mally closed valve in said line, and means mov 10 upon a predetermined movement of the pinion mounting means from neutral position. 18. In an internal combustion free piston en gine, a piston synchronizing means, and a fuel charge pump having a reciprocally movable fuel charge control member, means yieldingly oppos ing movement of said member to increase the fuel charges, manually controlled means operable to yieldingly move said member in opposition to said 10 yielding means, and to control movement of the 15. An arrangement as called for in claim 12 member in the opposite direction to reduce the wherein the means which is operable to release fuel charges, and means rendered operable by said the trip means is of an electrical nature. synchronizing means when subjected to a prede 16. In an internal combustion free piston en termined strain caused by load shock or a de able by the carriage to open the line. gine having a fuel charge pump, and a piston 15 phased piston condition to quickly move said con synchronizing means, a control for said pump trol member to predetermined charge reducing including a reciprocally movable member movable in one direction to increase the fuel charge and in the other direction to reduce the fuel charge, means movable to retracted position and operable when released from such position to quickly move said member a predetermined extent in charge reducing direction, and means rendered operable by said synchronizing means to release said re tractable means from retracted position when a predetermined stress resulting from load shock position against the tension of said yielding means and without disturbing an adjusted position of the manual control means. 19. In an internal combustion free piston en gine, a fuel feed means, a piston synchronizing means with a part yieldlngly movable in response to piston dephasing stresses, means for actuating the fuel feed means to reduce the fuel feed, and means operable .by predetermined yielding move ments of said part to render said last means or a dephased piston condition is applied to the active. synchronizing means. 20. An arrangement as called for in claim 19 17. In an internal combustion free piston en wherein the last-mentioned means includes an gine having a fuel charge pump and a piston syn 30 electrical control feature. chronizing means including a pinion, means 21. An arrangement as called for in claim 19 mounting the pinion for yielding reciprocatory wherein the last-mentioned means includes a hy movements transverse to its axis and from neu draulically operable control feature. tral position when a stress resulting from load 22. In an internal combustion free piston en shock or a dephased piston condition is applied 35 gine, a fuel feed means including a feed line, a thereto, a fuel control for said pump operable to valve in said line operable to render the fuel feed shut off the fuel charge supply, means normally held inactive and being operable, when released from inactive position, to effect a sudden move ment of- said control to shut-01f position, trip means for holding said last means in inactive position, and means rendered operative by said pinion mounting means to release said trip means to the engine inoperative, a piston synchronizing means with a part yieldingly movable in response to piston dephasing stresses, and means connect ing said part and valve to move it to inoperative fuel feeding position when a predetermined piston dephasing stress is applied to said part. FRANK M. LEWIS.