US1356820A - Reversing mechanism for internal-combustion engines - Google Patents

Description

R. HILDEBRAND.

REVERSING MECHANISM FOR INTERNAL COMBUSTION ENGINES. APPLICATION FILED IUNEZ, I919.

1,356,820, Patented Oct. 26,1920.

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R. HILDEBRAND.' -REVERSING MECHANISM FOR INTERNAL COMBUSTION ENGINES.

APPLICATION FILED IUNEZ, 1919. I

Patented Oct. 26, 1920.

4 SHEET$SHEET 2.

R. HILDEBRAND.

REVERSING MECHANISM FOR INTERNAL COMBUSTION ENGINES.

APPLICATION FILED JUNE 2. 1919.

1,356,820. Patqnted Oct. 26,1920.

4 SHEETS-SHEET 3.

R. HILD EBRAND.

REVERSING MECHANISM FOR INTERNAL COMBUSTION ENGINES. APPLICATION FILED JUNE 2. 1919.

1,356,820, Patented Oct. 26,1920.

4 SHEETS-SHEET 4.

v ling member hereinafter referred to as a UNITED STA REINHARD HILDEBRAND, 0F WEBSTER GROVES, MISSOURI. ASSIGNOR OF ONEeHALF TO GEORGE D. POGUE, OF PHILADELPHIA, PENNSYLVANIA.

REVERSING MECHANISM FOR INTERNAL-COMBUSTION ENGINES.

Specification of Iet'ters Patent. Patented Oct. 26, 1920.

i Application filed June 2, 1919. L Serial No. 301,256.

To all whom it may concern Be 1t known that I, REIXHARD HILDE- BRAND, a 'CltlZGIl of Germany, reslding at 'ebster Groves, Missouri, have invented a certain new and useful Improvement in Reversing Mechanisms for Internal-Combustion Engines, of' which the following is a full, clear, and exact descriptiom such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to reversing mechanisms of. the kind that are used in connection with marine internal. combustion en gines for changing the direction of rotation of the crank shaft, and particularly to reversing mechanisms of the typ ein which the change in the direction of rotation of the crank shaft is effected by changing the relationship between the rocker arms or valve actuating devices and two separate and distinct sets of cams on the cam shaft, one of which sets cooperates with. the rocker arms when the crank shaft is rotating forwardly and the other when the crank shaft is rotating, rearwardly.

One bject of my invention is to provide an inexpensive reversing mechanism for internal, combustion engines which does not comprise a materially greater number of parts than the reversing mechanisms used on stationary engines.

Another object is to provide a reversing mechanism which is so constructed and combined with the controlling mechanism for the engine that the fuel valve which regulates the supply of fuel to the engine has to be closed before the. reversing mechanism can be operated.

Another object is to provide a reversing mechanism that comprises a single controlreversing member. which, upon being. moved by the operator in charge of the engine, renders the rocker arms inoperative with relation to the set of cams on the cam shaft with which they have been cooperating. trips a locking mechanism which holds said cams in alinement with said rocker arms. causes the other set of cams to be brought into alinement with 'said rocker arms and thereafter brings the rocker arms into oprocker arms wi h rocker arms to be locked in alinement with each other.

And still another object is to provide a reversing mechanism of the character just i referred to, which is' so constructed that the operator in charge of the engine can easily v determine whether or not the cooperating parts or elements of same are functioning properly while the reversing member is being moved from one position toanother. Other objects and desirable features of my invention will be hereinafter pointed out.

In the preferred form of my invention, as herein shown, the operative and inoperative relationships between the rocker arms and the cams on the cam shaft are established by moving the fulcrums of all of the rocker arms simultaneously relatively to the cam shaft, the alinement of therocker arms with the two sets of cams on the cam shaft is effected by shifting the cam shaft longitudinally and the locking of the rocker arms in alinement with one or the other set of cams on the cam shaft is obtained by means of a lockingdevice that cooperates with the cam shaft. I wish it to be understood, how-. ever, that my inventionis not limited to a reversing mechanism of 'the particular design -or construction herein illustrated, as my broad idea consists in a reversing mechanism comprising a reversing member, which. upon being moved by the operator in charge of the engine, produces the following results,na 1nely, renders all of the set of cams on the cam shaft, trips the locking means that governs the alinement of the said cams, causes the other 'set of cams to be brought into alinement ber starts to. move from one position into another, and the means for shifting the cam shaft longitudinally preferably consists of a double acting servo motor directly con,-

nected with the cam shaft, or two single acting servo motors arranged at the opposite ends of the cam shaft and directly connect ed with same. The servo motor or servo motors may either be operated by electricity or a medium under pressure. and the device or devices which control the operating medium for said motors are combined with the reversing member of the mechanism in such a manner thatthey will be directly controlled by said reversing member. The locking means that holds the cam shaft in either of its two positions is also combined with the reversing member in such a manner that said locking means will be rendered inoperative and then restored to its normal position while the reversing member is being moved from one position to the other. Any preferred type of controlling means may be used for governing the operation of the engine, but the reversing member is combined with the controlling means in such a manner that the fuel valve which governs the supply of fuel to the engine will have to be closed before the reversing member can be moved to change the direction of rotation of the crank shaft of the 'engine.

F lgure 1 of the drawings is a front elevz tional view of a marine internal combustion engine of the Diesel type equipped with a reversing mechanism constructed in accordancewith my invention.

Fig. 2 is a vertical cross sectional view of said engine.

Fig. 3 is an enlarged detail view, illustrating one of the rocker arms and the two cams on the cam shaft thatcooperate with said rocker arm.

Fig. 4 is a view taken at right angles to Fig. 3.

Fig. 5 is a detail view, illustrating the locking means for the'cam shaft.

Fig.6 is a detail sectional view of one of the servo motors.

Fig. 7 is a side elevational view of the reversing member. the controlling mechanisni for the engine and certain of the parts that are combined with and directly operated by the reversing member.

Fig. 8 is a front elevational view of the parts shown in Fig. 7.

Fig. 9 is a vertical sectional view, taken on the line 9-9 of Fig. 7; and

Fig. 10 is a horizontal sectional view, taken approximately on the line 10-10 of F i 7 eferring to the drawings which illustrate the preferred form of my invention. 1 designates the rocker arms orvalve operating devices of a marine internal combus tion engine of the Diesel type. A designates a cam shaft provided with cams that actuate the rocker arms 1. and 2 designates the crank shaft of the engine which is operatively connected in any suitable manner with the cam shaft A. In the engine herein shown thecam shaft A is composed of two sections athat are joined together bv a coupling device a, as shown in F igi 1, said coupling device being inclosed in a hollow gear 2 that forms part of the mechanism for transmitting movement from the crank shaft 2 of the engine to the cam shaft A. In order that the direction of rotation of the crank shaft 2 may be reversed, the cam shaft A is provided with a set of cams 3 that are adapted to be brought into alinement with the rocker arms 1 when it is desired to .have the crank shaft of the engine rotate forwardly, and a separate and distinct set of cams at that are adapted to be brought into alinement with said rocker arms when it is desired to have said crank shaft rotate rearwardly, the cam shaft A being normally arranged either in one position,which I will refer to as its ahead position, or in another position, which I will refer to as its astern position.

My invention consists in a reversing mechanism for changing the relationship between the rocker arms and the cams on the cam shaft so as to cause said rocker arms to cooperate with either set of cams at the will of the operator in charge of the engine. In the preferred form of my invention, as herein shown, two cams 3 and 1 are provided for each of the rocker arms 1 and all of'the rocker arms are pivotally mounted on a common fulcrum member consisting of a shaft B that is arranged parallel to the cam shaft A. as shown in Fig. 3. The rocker arms 1 are rendered operative and .inoperative with relation to the cams on the cam shaft A by turning the fulcrum member B relatively to the cam shaft so as to move the rollers 1 on the rocker arms 1 into or out of the path of movement of the operative set of cams on the cam shaft. In the form of my invention herein illustrated the fulcrum member B consists of an eccentrically mounted shaft. which, upon being rotated in the direction indicated by the arrow in Fig. 3, causes the rollers 1 on the rocker arms to be moved upwardly out of the path of the set of cams on the cam shaft which are then in alinement with said rocker arms. After the rocker arms have been rendered inoperative with relation to the cams. as just referred to, the cam shaft A is moved longitudinally so as to shift the other set of cams on the cam shaft into alinement with the rocker arms. If. for example, the cams 3 are cooperating with the rocker arms and it is desired to reverse the engine. the operator in charge of the engine actuates a means that causes the rocker arm shaft or fulcrum member B to move-into the position shown in dotted lines in Fig. 3 and the cam shaft A to move longitudinally into such a posi- .engine to. start. hen the engine has in Fig. 9.

If desired, a visual indicator F may be employed so as to show at all times the position of the cam shaft A, theindicator F herein shown consisting of a hand or pivotally mounted device arranged in prox-.

imity to the quadrant 30 so that it will point to the words ahead," neutral and astern on said quadrant, depending upon the position of the cam shaft. said indicator F being secured to a shaft provided with an arm 31 that is joined by means of a link 32 to an arm 33 secured to one member of a reduction gearing. indicated as an entirety by the reference character 11: in Fig. 1. that is operatively connected by means of a rack bar 35 to'a yoke or fork 36 which fits in a groove in .the cam shaft A. \Vhen the crank shaft of the engine isrotating forwardly the indicator F will occupy such a position that it points to the word ahead on the quadrant 30. and when the cam shaft A is shifted longitudinally into its astern position. the indicator F will swing to the right. looking at Fig. 8. into such a position that it will point to the word astern on the quadrant.

The fuel pump that regulates thesupplyof liquid fuel to the engine and the means for controlling the starting. air and for governing the operation of the distributing valves of theengine have not been illustrated. as they form no part of my present invention. The controlling member, however. which governs the fuel pump, starting air and distributing valves is herein illustrated as a hand wheel G that is arranged in proximity to the reversing member C. Said controlling wheel G has to make four distinct movements in starting the engine. each movement being approximately a quarter turn. Assuming that the engine is at rest and it is desired to start the engine, the first quarter turn of the controlling member G admits compressed air to the starting valves of all of the cylinders, thereby causing the gained a certain speed the controlling member G is given a second quarter turn which shuts off the starting air from some of the cylinders and causes said cylinders to be supplied with fuel. After these cylinders have started to fire the controlling member G is given another quarterturn so as to completely shut off the starting air and cause all of the cylinders to be supplied with fuel; thereby causing the engine to generate its maximum power at the end of the third quarter turn ofthe controlling wheel G. Any further turning of the controlling by the engine. During the first three quar-v ter turns of the controlling wheel G, howi ever, a ratchet mechanism operates to pre vent the wheel G from being turned rear wardly after it has been started on its cycle. In order to prevent the operator from moving the reversing member C without first cutting offthe supply of fuel to the engine. means is provided for interlocking the reversing member C with the controlling member G of the engine in such a manner that said reversing member can not be moved unless the controlling member G stands in a certain position. The interlocking device herein illustrated comprises one or more disks 3? on the reversing shaft 5, each of which is provided with two flattened sides 37", as shown in Fig. 8. The vertically-disposed shaft 38, to which the controlling wheel G is connected, is arranged in vertical alinementwvith the reversing shaft 5 and is provided at its lower end with anoblong-shaped member 39 that is adapted to cooperate with the disks 3?. The member 39. and the'disks3T are so formed and arranged that when the engine is in normal operation the member 39 stands crosswise of the disks 3?, thereby preventing the reversing member C from being turned without first moving the controlling member G to cut off the supply of fuel and arrange the member 39 in parallel relation with the disks 37, as shown in Fig. 10. lVhen the reversing member C stands in either its ahead position or in its astern position the controlling member G can be operated due to the fact that the flattened sides of the disks 3? lie below the member 37. hen the reversing member stands in its neutral position however, as shown in Figs. 7, 8 and 10, the disks embrace the member 39, and thus prevent the controlling member G from being operated. Consequently, it is impossible to start the engine when the reversing mechanism is in an improper position, namely, in such a position that one or the other set of cams on the cam shaft A is not in alinement with the rocker arms 1 and. it is impossible for the operator in charge of the engine to reverse the engine before he has turned off the supply of fuel to the engine. or at least, turned the controlling wheel G far enough on the last quarter turn turn of its cycle to greatly reduce the speed of the engine.

From the foregoing it will be seen that my improved reversing mechanism is so constructed that in the operation of reversing the engine the rollers on the rocker arms are first removed from the set of cams on the cam shaft with which they have been cooperating, the cam shaft is then shifted longitudinally so as to bring the other set of cams thereon into alinement with the rocker arms and thereafter the rollers on the rocker arms are brought into position to cooperate with said second set\of cams. The movement of the rocker arms into and out of operative position with relation to the cams on the cam shaft is effected by bodily moving the shaft B on which all of the rocker arms are fulcrumed, and the longitudinal shifting of the cam shaft is effected either by means of a double acting servo motor directly connected with the cam shaft, or by means of two single acting servo motors arranged at the opposite ends of the cam shaft and directly connected with same. \Vhen two single acting servo motors of the type herein illustrated are employed, one servo motor will act as a dash pot or retarding device to prevent the cam shaft from moving too abruptly, due, of course, to the factthat the longitudinal movement of the cam shaft causes the piston of the inoperative servo motor to move toward the head of the cylinder of said motor, and thus gradually expel the air in the dash pot of said cylinder through the leak port or discharge opening 18 leading from said cylinder. During the actual running of the engine the pipes 17 and '17 leading from the casings of the controlling valves to the cylinders of the" servo motors are vented by the lealr grooves 21 and 22 in the stems of the valves 21 and 22, respectively. It is only during the operation of reversing the engine that the operating medium is supplied to the servo motors. At all other times the controlling valves 21 and 22 are seated so as to cut the word fahead on the quadrant 30, the

rocker arms 1 are in operative position with relation to the cam shaft, the cams 3 on said cam shafts are in alinement with said rocker arms and the locking device E is in en agement with the groove 24 of the collar on the cam shaft A. To reverse the engine the operator first turns the controlling wheel G so as to cut off the supply of fuel to the engine and arrangeithe substantially oblongshaped member 39 on the lower end of the controlling shaft 38 in parallel relation with arrow in Fig. thereby rendering all of the rocker arms 1 inoperative with relation to the cam shaft and also causing the locking device E to be moved upwardly out of locking engagement with the cam shaft. This movement of the reversing member C, namely, from its ahead to its neutral position, causes the cam 23 on the reversing shaft 5 to wipe past the spring-pressed valve lever 21 that cooperates with the val"e,21 without, however, opening or unseating said valve 21, due, of course, to the fact that the cam 23 engaged the valve lever 21 and moved it downwardly away from the lower end of the stem of the valve 21. Just before the cam 23 reaches the neutral position shown in Fig. 9 the valve lever 21 snaps upwardly into engagement wit-h the stem of the valve 21. As shown in Fig. 9 the valve levers 21 and 22 are combined with springs 21* and 22 that normally hold said levers in engagement with the stems of their respec- 9'5 tive valves. During the second part of the movement of the reversing member C from 'its neutral into its astern position the cam 23 on the reversing shaft 5 engages the valve lever 22 and moves said valve lever in a direction to unseat the valve 22, thereby causing compressed air to be admitted to the servo motor D so as to cause the piston of saidmotor to move the cam shaft A longitudinally to the left," looking at Fig. 1, and thus bring the cams 4 on said cam shaft into 'alinement with the *rocker arms 1. The valve 22 seats or closes as soon as the cam 23 passes out of engagement with the roller on the valve lever 22, and while the cam shaft is moving longitudinally in the direction, P previously referred to, the servo motor- D acts as a dash pot to retard the movement of the cam shaft and prevent it from moving abruptly from its ahead into its astern position. By the time the cam shaft reaches its astern osition the arm 9, which is connected by means of the gears 6 and 7 with the reversing shaft 5, will have been brought into such a position that the rocker arms are 120.

restored to operative relationship with the cams 4 on the cam shaft and the locking device E moved into engagement with the groove 24* in the collar E on the cam shaft.

It will thus be seen that in my improved reversing mechanism a single manipulation of the reversing member C either from, its.

ahead position to its'astern position or from its astern' posltion to its ahead position successively operates the various elements that v ters Patent, is

effect a change in the direction of rotation of the crank shaft of the engine. This is a. very desirable feature of a reversing mechanism for internal combustion engines, as it is exceedingly simple; it is inexpensive to manufacture; and it is simple to understand and operate.

I The locking device E is preferably so constructed that it will be out of engagement with the cam shaft during the major portion of the time, when the reversing member C is moving from its neutral into its ahead position or into its astern position. This is a desirable feature, in that it gives ample time for the servo motor which is then operating to shift the cam shaft longitudi- 'nally. In casethe reversing member C is moved too quickly, or in case the servo motor which is then operating is too sluggish, the locking device E will engage the collar E on the cam shaft without entering one of the grooves in said collar. No damage results, however, to any of the parts of the'mechanism, because it is impossible for the operator to complete the movement of the reversing member C or move it into its final position intil the cam shaft A reaches such a position that the locking device E is in alinement with the proper groove in the collar E on the cam shaft. Accordingly, the locking device E, in addition to securely locking the cam shaft in one or the other of its positions, also enables the operator in charge of the engine to determine whether or not the servo motors are acting properly, for if the servo motor that is operative is sluggish, it will be impossible for the operator to turn the reversing member C into its final position. This additional function of the locking device E is not relied upon,

however to insure the proper operation of the mechanism, for the visual indicator F constitutes a means that enables the operator to see at all times just how the servo motors are acting, for when the cam shaft has reached one or the other of its normal positions, the indicator F will point either to the Word ahead or astern on the quadrant 30.

Having thus described my invention, what I claim as; new and desire tosecure by Let- 1. An internal combustion engine provided with valve operating devices, an opcrating means for said devices comprising two sets of cams, one of which sets cooperates with said devices when the crank shaft of the engine is rotating forwardly and the other when the crank shaft is rotating rearwardly. a reversing member, mechanism op-, erated by said reversing member for rendering said'valve operating devices inoperative with respect to the cams with which they have been cooperating when said reversing member moves from one of its positions to its other position, a motor adapted to be actuated by anroperating medium for causing the other set of cams to be brought into alinement with said devices, and means governed by said reversing member for conshaft of the engine is rotating forwardly.

and the other set alining with said devices when the crank shaft is rotating rearwardly, a locking'means for holding said valve op erating devices in alinement with one or the other set of cams, a reversing member that normally occupies one of two positions, and means whereby the movement of said reversrenders said valve operating devices inoperative with'respect to the cams with which they have been cooperating, renders said locking means inoperative, causes the other ing member from one position to another set of cams to be brought into alinementwith said valve operating devices and finally establishes operative relationship bet-ween said valve operating devices and said sec- 0nd set of cams and alsorenders said 'op erating mechanism operative.

3. An internal combustion engine provided with a controlling member for governing the operation of the fuel pump, starting air and distributing valves of the en-- gine, a reversing member that normally occupies one of two positions, means for causing the direction of rotation of the crank shaft of the engine to be reversed when said reversing member is moved from one of its positions to its other position, and means for preventing said controlling member from being actuatedwhilesaid reversing member is being moved from one of its positions to its other position or .whenit is standing in an intermediate position. I

l. An internal combustion engine provided with a controlling member for gov erning the operation of the fuel pump, starting air and distributing valves of the engine, a reversing member that normally occupies one of two positions, means for causing the direction of rotation of the crank shaftof the engine to be reversed when said reversing member is moved from one of its positions to its other position, and means for preventing said reversing member from being operated or. moved before the control group of elements that cooperate with said devices to cause the crank shaft of the engine for rendering the valve actuating devices inoperative with relation to one of said groups of elements, a motor adapted to be actuated by a medium under pressure for moving the other group of elements into operative position with relation to said devices, and means operated by said reversing member for controlling the medium that actuates said motor of elements.

6. An internal combustion engine,

of the engine, a 'cam shaft provided with two sets of cams, one or the other of which sets is normally in alinement with said rocker arms, a locking device for said cam shaft operatively connected with said rocker arms, means for rendering said rocker arms inoperative with relation to the cams that are arranged in alinement with same and.

said arms have been brought into alinement with said second set of cams.

7. An internal combustionengine provided with rocker.v arms for actuating the valves of the engine, a cam shaft provided with two sets of cams, a locking means for holding said cam shaft in such a position that one or the other sets of cams thereon will aline with said rocker arms, means forrendering 'said locking means inoperative, and means for shifting said cam shaft longitudinallyso as to move one of the sets of' cams thereon out of alinement with the rocker arms and bring the other set of cams into alinement with the rocker arms.

8. An internal combustion engine, comprising rocker arms for actuating the Valves of the engine, a shaft on which all of said rocker arms, are fulcrumed, a shiftable cam shaft provided with two sets of cams that are adapted to cooperate with said rocker arms,'and means for moving said rocker arm shaft bodily relatively to said cam shaft so as to render the rocker arms inoperative with relation to the cams on the cam shaft preparatory to shifting the cam shaft. w 1

9. An internal combustion engine, comprising rocker arms for'actuating the valves of the engine, an eccentricallymounted shaft on which said rocker arms are fulcrumed,

a shiftable camshaft provided with sepa-.\

rate and distinct sets of cams that are adaptcom-' )risin rocker arms for oaeratin the valves ed to cooperate with said rocker arms, and means for turnmg sald rocker arm shaft so as to bodily shift same and thus render the rocker arms operative or inoperative with relation to said cams.

10. An internal combustion engine provided with rocker arms for actuating the v valves of the engine, a fulcrum member common to all of said rocker arms, a cam shaft provided with two sets of cams for cooperating with said rocker arms, one or the other of which sets is adapted to cooperate with the rocker arms, depending upon the direction of rotation of the crank shaft of the engine, means for moving said fulcrum member first in one direction, to render the rocker arms inoperative-and thereafter back to normal position to render said rocker arms operative, and means separate and distinct from said fulcrum member and operated independently of same for shifting the cam shaft longitudinally "when the rocker arms are inoperative so as to move one set of cams outof alinement with the rocker arms and the other set of cams into alinement with said rocker arms.

11.. An internal combustion engine provided with rocker arms for actuating the valves of the engine, a fulcrum member common to all of said rocker arms, a cam shaft provided with two sets of cams for cooperating with said rocker arms, one or the other of which sets is adapted to cooperate with the rocker arms, depending upon the direction of rotation of the crank shaft of the engine, means for moving'said fulcrum member first in one direction to render the rocker arms inoperative and thereafter back to normal position to render said rocker arms operative, means for shifting the cam shaft longitudinally when the rocker arms are inoperative so as to move one set of cams out of alinement with the rocker arms and the other set of cams into alinement with cam shaft, and means for rendering said locking device inoperative when the fulcrum member is moved to render the rocker arms inoperative and for moving said locking device back into engagement with the cam shaft when said fulcrum member is restored to its normal position. I

12.:An internal combustion engine provided with rocker arms for actuating the Valves of the engine, a shiftable cam shaft provided with two sets of camsfor cooperating with said-rocker arms, a piston that bears directly against one end of said cam shaft and shifts it, longitudinally so as to change-the relationship between said rocker arms and the cams on said shaft, and means for supplying an operating medium to the cylinder in which said piston is arranged.

13. An internal combustion engine, com;

vices, a cam shaft provided with a plurality of sets of cams for cooperating with said rocker arms. servo motors arranged at the opposite ends of said cam shaft for shifting said shaft longitudinally so as to change the relationship between the rocker arms and the cams on said shaft, a manually-operable reversing member. means for rendering said rocker arms inoperative with relation to said cam shaft during the first part of the movement of said reversing member, and an independent means governed by said reversing member for thereafter supplying one of said servo motors with an operating medium.

14. An internal combustion engine, comprising rocker arms or valve operating devices, a cam shaft provided with a plurality of sets of cams for cooperating with said rocker arms. and a shifting means for said shaft comprising devices arranged at the opposite ends of said shaft and each composed of a cylinder and a piston in said cylinder that bears against one end of the cam shaft. one of said devices acting as a dash pot to retard the movement of said cam shaft when the piston of the other device is moving under the influence of an operating medium supplied to its cylinder.

15. An internal combustion engine, comprising rocker arms or valve operating devices, an eccentrically mounted shaft on which all of said rocker arms are fulcrumed, a shiftable cam shaft provided with two sets of cams for cooperating with said rocker arms, servo motors arranged at the opposite ends of said cam shaft for shifting it longitudinally, a reversing member, a mechanical connection between said reversing member and rocker arm shaft for turning said rocker 'arm shaft so as to disengage the rocker arms from the cams, and an independent means governed by said reversing member for causing one of said servo motors to operate so as to shift the cam shaft longitudinally.

16. An internal combustion engine, comprising rocker arms or valve operating devices. an eccentrically mounted shaft on which all of said rocker arms are fulcrumed, ashiftable cam shaft provided with two sets of cams for cooperating with said rocker arms, a locking device that is capable of holding said cam shaft in either one of two positions. servo motors arranged at the oposite ends of said cam shaft for shifting it ongitudinally, a reversing member that normally stands in either one of two positions, and means operated by said reversing member for turning said rocker arm shaft in a direction to render the rocker arms inoperative, for disengaging the locking device from said cam shaft. for causing one of the servo motors to shift the cam shaft longitudinally and for restoring the rocker arm shaft and the locking device to' their normal positions when said reversing member is erning the operation of said shifting means.

said locking device being so constructed that said reversing member can not be moved to its final position until after said cam shaft has reached its final position during the operation of shifting said shaft.

18. An internal combustion engine, comprising rocker arms or valve operating devices, ashiftable cam shaft provided with two sets of cams for cooperating with said rocker arms. single acting servo motors arranged at the opposite ends of said shaft for shifting it longitudinally in opposite directions, valves for governing a medium used to actuate said servo motors,a reversing member that normally stands in one of two positions, a mechanical means actuated by said reversing member for rendering said rocker arms inoperative with relation to the cams on said cam shaft, and an independent means actuated by said reversing member for causing one of said valves to operate when said reversing member is moved from one position to the other and for causing the other valve to operate when said reversing member is restored to its former position.

19. An internal combustion engine, com-' prising rocker arms or valve operating devices, an eccentrically mounted shaft on which said rocker arms are fulc'rumed, a shiftable cam shaft provided with two sets of cams for cooperating with said rocker arms, servo motors arranged at the opposite ends of said cam shaft for shifting it longitudinally in opposite directions, devices for governing the medium used to actuate said motors. a reversing member, means operated by said reversing member forturning said rocker arm shaft so as to render therocker arms inoperative and for thereafter actuating one of the devices that controls the operating medium for one of the servo motors so as to cause said motor to shift the cam shaft longitudinally, a controlling member for the engine, and an interlocking mechanism between said cont-rolling member and reversing member that prevents the reversing member from being operated without first moving the controlling member to cut off the supply of fuel to the engine and for preventing said controlling member from being operated when the reversing member by said reversing member for turning said:

rocker arm shaft so as to render the rocker arms inoperative and for thereafter actuat-.

ing one of the devices. that controls the operating medium for one of the servo motors so as to cause said motor to shift the cam shaft longitudinally, a controlling member for the engine, and cooperating devices combined with said controlling member and with said reversing member and constructed in such a manner that said controlling member can not be moved when said controlling member is in an improper position and said reversing member can not be moved when said controlling member is in an improper position.

21. An internal combustion engine, comprising a cam shaft provided with a double set of cams, rocker arms adapted to cooperate with said cams, an eccentric shaft on which said rocker arms are fulcrumed, means for locking the cam shaft in two positions so as to hold eitherset of cams in alinement with said. rocker arms, means for successively unlocking the cam shaft and simultaneously turning the rocker arm shaft so as to move the rocker arms into an inoperative position with relation to said cams, means for shifting the cam shaft longitudinally and for thereafter relocking the cam shaft and restoring all of the rocker arms to operative relationship with one set of cams on the cam shaft.

22. An internal combustion engine, comprising rocker arms or valve erating devices, a' cam shaft composed o a plurality of sections, a coupling device for joining said sections together, and mechanism for transmitting movement from the crank shaft of the engine to said cam shaft comprising vice.

vided with a cam 'shaftthat is adapted to be shifted longitudinally when it is desired to reverse the engine, servo motors arranged atthe opposite ends of said shaft for moving said shaft longitudinally in opposite directions and arranged so that one motor acts as a dash pot to retard the movement of said shaft when it is being shifted by the other motor, and a reversing member for controlling the operation of both of said servo motors.

24. An internal combustion engine, comprising a cam shaft that is adapted to be shifted longitudinally to change the direction of rotation of the crank shaft of the engine, a locking device for saidcam shaft that is capable of holding said shaft in either one of two positions, a reversing member, a connection between said reversing member and locking device, means controlled by said reversing member for shifting said cam shaft longitudinally, said locking device being so constructed that it will prevent said reversing member from being moved to its final position before the cam shaft completes its movement in one direction, and a visual indicator combined with sa1d camrshaft' for indicating the position of said cam shaft.

25, An internal combustion engine provided with as'hift-able cam shaft, a housing for said cam shaft, and servo motors carried by said housing for shifting said cam shaft longitudinally. 26. An internal combustion engine provided with rocker arms, a shaft/on which said rocker arms are fulcrumed, an operat- 23. An internal combustion engine 'proing mechanism for said rocker arms, and

means for rotating and bodily shifting said shaft so as to render said rocker arms inoperative with respect to said operating mechanism.

27. An internal combustion .engine provided with rocker arms, an eccentrically mounted shaft on which said rocker arms are fulcrumed, an operatingmeans for said rocker arms, and means for turning said rocker arm shaft so as to render said rocker arms inoperative with relation to said operating means. I

REINHARD HILDEBRAND.

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