US2657776A - Throttle control device for internal-combustion engines - Google Patents

Description

s. M. PARKER 2,657,776

THROTTLE CONTROL DEVICE FOR INTERNAL-COMBUSTION ENGINES Nov. 3, 1953 5 Sheejs-Sheet l F'i led Sept. 17, 1951 5 Sheets-Sheet 2 Nov. 3, 1953 s. M. PARKER THROTTLE CONTROL DEVICE FOR INTERNAL-COMBUSTION ENGINES Filed Sept. 17, 1951 3 s. M. PARKER ,776

THROTTLE CONTROL DEVICE FOR INTERNAL-COMBUSTION ENGINES Filed Sept. 17, 1951 5 Sheets-Sheet 3 S. M. PARKER Nov.- 3, 1953 THROTTLE CONTROL DEVICE FOR INTERNAL-COMBUSTION ENGINES 5 Sheets-Sheet 4 Filed Sept. 17 1951 5. M. PARKER Nov. 3, 1953 THROTTLE CONTROL DEVICE FOR INTERNAL-COMBUSTION ENGINES 5 Sheets-Sheet 5 Filed Sept. 17, 1951 l. ullllfllllllilllfll Patented Nov. 3, 1953 THROTTLE CONTROL DEVICE FOR INTERNAL-COMBUSTION ENGINES Sydney Macdonald Parker, Leamington Spa, England, assignor to Automotive Products Company Limited, Leamington Spa, England Application September 17, 1951, Serial No. 246,919

6 Claims.

This invention relates to throttle control devices for internal combustion engines, and has for its object to provide a device, independent of the normal throttle control mechanism, which temporarily limits to a predetermined range the possible setting of the throttle. The device is primarily intended to provide an appropriate setting of the throttle during the changing of gears in a variable-speed gear box associated with an engine, being operated for that purpose by the change speed gear control.

According to the invention a throttle control device includes at least one stop which is movable into its operative position to limit the range of movement of the throttle valve upon actuation of a control other than the normal throttle control, the said stop, in moving to its operative position, adjusting the throttle valve independently of the normal throttle control if the position of the latter is such as to position the throttle valve at a, setting outside the limited range.

Further, according to the invention a throttle control device for the engine of a vehicle includes at least one stop which is movable into its operative position to limit the range of movement of the throttle valve upon operation of a change-speed gear control to disengage a gear and returned to a position in which it does not obstruct movement of the throttle valve through its full normal range when a gear is engaged, the said stop, in moving to its operative position, adjusting the throttle valve independently of the normal throttle control if the position of the latter is such as to position the throttle valve at a setting outside the limited range. v

The throttle valve is preferably positively con nected to a member co-operating with the stop, and the normal throttle control mechanism acts on the said member through a resilient element so that the member can move independently of such mechanism.

Two stops may be provided one of which, in its operative position, defines the upper limit of a range of movement of the throttle valve the other limit of which is the closed position of the said valve, whilst the other, in its operative position, defines the lower limit of a range of movement of the throttle valve of which the other limit is the maximum normal throttle open- 2 tion, together with parts of a gear-changing mechanism with the operation of which the throttle control device is associated;

Figure 2 is a detail view showing a pair of switches operated by the gear-changing mechanism of Figure 1;

Figure 3 is a side elevation of the throttle control device shown diagrammatically in Figure 1;

Figure 4 is a section on the line l4 of Figure 3;

Figure 5 is a plan view of the device shown in Figure 3;

Figure 6 is a diagram, similar to Figure 1, showing another form of throttle control device according to the invention, and parts of the gearchanging mechanism with which it is associated;

Figure '7 is a side elevation of the throttle control device shown diagrammatically in Figure 6;

Figure 8 is a sectional elevation of a vacuum control valve and its operating solenoids;

Figure 9 is a section on the line 9-9 of Figure 8;

Figures 10, 11 and 12 show a switch arrangement for operating the throttle control device shown in Figure 6, Figure 9 being a side view and. Figures 11 and 12 being sections on the lines Il-H and l2l2 of Figure 10 respectively;

Figure 13 is a view of another switch mechanism for operating the throttle control device shown in Figure 6, looking along the steering column of a vehicle to which the switch mechanism is attached;

Figure 14 is a section on the line l4l4 of Figure 13; and

Figure 15 is a view similar to Figure 7 showing a modification.

Referring to Figures 1 to 5 of the drawings, and more particularly to Figure 1, the throttle control device is shown at 20, and a liquid pressure operated gear-changing mechanism at 2|. The mechanism 2| operates a gear-box (not shown) of the well-known synchro-mesh type having four forward gears and reverse, through two links 22 and 23 which effect respectively the selection of the appropriate shift bar of the gear-box and the movement of the selected shift bar to engage the gear. The mechanism 2| comprises a double-acting liquid pressure cylinder 24 in which is operable a piston 25 provided with cams with which co-operate followers mounted on bell-crank levers pivoted to the links 22 and 23. Liquid is supplied to the cylinder 24 from a suitable pressure source through a sliding plunger valve 26 of known type having a followup action the valve being closed when its plunger is in an intermediate position, and being opened by movement of the plunger in either direction, movement in one direction admitting liquid to one end of the cylinder and allowing it to escape from the other end, whilst movement in the opposite direction admits liquidto the said other end of the cylinder, and allows liquid to escape from the said first end.

The valve 26 is operated through a rod 21 and floating lever 28 from a hand lever 29 movable in a quadrant 30, the floating lever 28 being pivoted to a link 3| itself pivoted at one-end tora bell-crank lever 32 carryinga. cam follower engaging a cam surface on the piston. 25, and coupled at its other end to a return spring 33. The hand lever 29 moves towards'the left for downward gear changes, and towards the right for upward gear changes, the plunger of the valve 26 moving in the opposite direction in each case, owing to the reversing action of thefloating lever 28. 'The valve plunger extends right through the valve casing and carries an abutment 34'co-opcrating with the operating plungers of two electric switches 35 and 35 (Figure 2), both of which are open when the valve 23 is in its closed position, the switch 35 being closed by movement of the valve to the left in Figure 1 and the switch 36by movement of the valve to the right in Figure 1. The follow-up action of the valve 26 is produced by the movement of the bell-crank lever 32.resulting from movement of the piston 25, the arrangement being such that the plunger of the valve 26 returns to its intermediate position when a selected gear has been engaged. Thus the selection of any gear by movement or thelever 29 closes one of the switches 35. or 36, and the engagement of the gear re-opens that switch, the other switch remaining open throughout the gear changing'operation.

The throttle control device 20' is 'shown' in detail in Figures 3, 4 and 5. In those figures, 31 is the main passage in the carburettor body through which the mixture flows to the induction manifold of the engineyand 38 is the throttle valve, which is mounted on a Sp 39 P ing outwardly'atone end, the projecting end passing through a sleeve screwed into the carburettor body and itself projecting to form a bearing for a boss carrying an arm 4| connected by a cable 42 to a normal throttle control pedal, and connected also to a return'spring 43 anchored at a suitable point on the engine. Secured to the projecting end of the spindle 38 is another arm 44, and a tension spring 45 is connected between pins46 and 41 on the arms 4| and 44, the spring 45 tending to urge the two arms to relative positions in which the line of action of the said spring is radial to the spindle 39, as shown in Figure 3. The arm 44 carries a pin 48, ofisetwith respect'to the axis of the spindle 89, so that'it moves through an arcuate path as the throttle valve 38 opens or'closes.

A bracket 49 suitably secured to the carburettor body supports two co-axial solenoids 50 and the armatures 52 and53 of which carry slotted heads 54 and 55 into'the slots of which the pin 48 projects. When the solenoids are deenergised, the heads 54 and 55 occupy the positions shown in Figure 3, in which their slots coincide, and the pin 48 is'tree to move through an angle sufficient to allow the full normal range of movement of the throttle valve. The switches 35 and 36 respectively act to close electric circuits including the'solenoids 50 andfil, so that the solenoid 50 is energised when an upward gear change is effected, and the solenoid 5| is energised when a downward gear change is effected. A switch 56 (Figure l) controlled by the engagement of its operating plunger with the rod 21, isheld-intheclosed position when the hand lever 29. is in a position 101" selecting'any of the forward gears, but is opened when the hand lever 29 is moved to the neutral or reverse positions, by the operating lunger riding on to a reduced portion 51 of the rod, the switch 56 being in series with both the switches 35 and -36,:-so that, when it is open, the closing of these switches does not energise the solenoids.

.When the solenoid 50 is energised, the armature 52 thereof is drawn into the coil, thus moving the head 54 to the right, so that the lefthand end -of the slot therein acts as a stop to limit the movement of the pin 48 to the left, and so tolimit the openin of the throttle valve, for example to one eighth of its full opening movement. If the throttle valve is more than one eighth open, the arm '44 is turned as the head 54 moves to reduce the throttle opening, the arm 44 beingv turned relative to the arm 4| and tensioning the spring 45, so that the position of the normal throttle control is unaffected.

When the solenoid 5| is energised, the armature 53 is drawn into the coil of that solenoid, thus moving the head 55 to the left so that the right hand end of the. slot therein acts as a stop to limit themovement of the pin 48 to the right, and so limits .the closing of the throttle, for example to a .position in which it is threeeighthsopen. The throttle valveis moved-towards the open position it necessary, with relative movement of the arms 4| and 44.

v"li'hus each time'the handlever 29 is moved to the. right. to make an upward gear change, the switch 35 .is closed, energising'the solenoid 50. The throttle valve 38, is therefore set to a position in which it is not more than one eighth open, regardless of the position of'the throttle pedal, and. remains in'that position until the higher gear is engaged and the solenoid 50 de-energised, when, if the throttle pedal has been kept in a depressed position, the throttle valve reopens to a position corresponding to the pedal position.

When the hand lever 29 is moved to the left to make a downward gear change, the switch 36 is closedto energise the solenoid 5|, and the throttle valve 38, if it is less than three-eighths open, is moved with the head 55, so that it is at least three-eighths open, regardless of the position of the throttle pedal. The head 55 remains in its operative position until the lower gear is engaged and the solenoid5| de-energised, allowing the throttle valve to close if the throttle pedal has been released.

Figure 6 shows a form of throttle control device in which the throttle stops areactuated by suction derived from the suction manifold of the engine, the application or the suction being. controlled electrically, the throttle control beingassociated with gear change mechanism of the synchro-mesh type in which the gear changes are effected mechanically by movement of a lever mounted on a rod extending parallel to the steering column, the rod being moved axially to select the appropriate shift bar of the gear-box, and angularly to engage the gears. The throttle control unit is shown at 60, the electrically operated vacuum control valve attl, and the con- 5 trol switch at 62. A vacuum reservoir is shown at 63.

The throttle control unit 60 is shown in detail in Figure 7, the spindle of the throttle valve being shown at 64. The carburettor and throttle valve are not shown in the drawings. A sector-shaped plate 65 fixedly mounted on the throttle valve spindle 94, and a pin 99 projects from one side of the plate 65, at a point off-set from the axis of the spindle 64, to co-operate with two movable stops 61 and 68. Pivotally attached to the other side of the plate 95 is one end of a resilient link 99, the other end of which is pivoted to a lever I connected by a cable H to the normal throttlecontrol. A return spring 12 for urging the throttle valve to the closed position is also connected to the lever 10. The resilient link 69 comprises inner and outer telescoping members 13 and 14, the inner member 13 having a pair of opposed external shoulders 15 and 16, and the outer member having a pair of opposed internal shoulders I1 and E8, the two pair of shoulders being equally spaced. A pair of sleeves 19, urged apart by springs 80 between which is interposed a washer 9i, co-operate with the shoulders to urge the members 13 and 14 to a position in which the shoulders 15 and 11 are in a common plane and the shoulders 16 and 18 are in another common plane, extension or compression of the link causing compression of the springs.

The stops 61 and 98 are associated respectively with bellows 02 and 83. The bellows 82 has an inner end plate 90 fixed to a bracket 85, the stop 91 being carried by a rod 86 passing through the inner end plate 84 and secured to the outer end plate 81 of the bellows, and a spring 88 being incorporated in the bellows to extend it. The bellows 93 has inner and outer end plates 89 and 90 both fixed to a bracket 9i, and a movable intermediate plate 92 carrying a rod 93 slidable in the inner end plate 89, the rod 93 carrying the stop 69. The bellows 82, and the chamber 94 of the bellows 93 between the outer end plate 89 and the intermediate plate 92 have a common connection to the vacuum control valve 9i, and the other chamber 95 of the bellows 83 has a separate connection to the vacuum control valve BI. A spring 96 in the chamber 95 urges the intermediate plate 92 outwardly.

The vacuum control valve, which is shown in detail in Figures 8 and 9, comprises a body 91 having an axial bore 98 which is counterbored at both ends to provide recesses 99 and I00, the recesses being closed by end caps IOI, I02 formed with central openings I 93 and I04 respectively leading into chambers I and I06 in the end caps. A pipe ml, connected to the inlet manifold of the engine, leads into the bore 93, a nonreturn valve I88 being provided to prevent flow of air into the bore 98 from the inlet manifold. Another pipe I09 connects the bore 98 to the vacuum reservoir 63. A pipe I I0 leads from the recess 99 to the chamber 99 in the bellows 83, and a pipe III leads from the recess I00 to the chamber 94 in the bellows 83, and to the bellows 82. Another pipe I I2 leads from the recess 99 to a vacuum cylinder (not shown) for disengaging the clutch of the vehicle. The recess I00 and the chamber I05 are connected together by passages ii 3 (Figure 9). Solenoids H4 and H5 are mounted respectively on the end caps I 0| and I92, the armatures of the solenoids carrying respectively valve heads I I6 and H1 located in the recesses 99 and I00. The armaturesare urged inwardly by springs I I8 and H9 respectively to seat the valve heads on the shoulders at the inner ends of the recesses so as to close the ends of the bore 98, energisation of the respective solenoids drawing the valve heads outwardly so that they close respectively the openings I03 and I04 in the end caps IOI and I02. Air inlet ports I20 are provided in the end cap I02.

When both solenoids are de-energised, both valve heads are in their inner positions, and the three pipes H0, III and H2 are connected to the atmosphere through the ports I29, so that both stops 51 and 68 are withdrawn from their oper-' ative positions. When the solenoid H5 is energised, the recesses 99 and I00 are cut off from the ports I20, and suction is applied to all three pipes IIB, III and H2. As the suction acts on both sides of the intermediate plate 92 in the bellows 83, the stop 58 is not affected, but the suction acting in the bellows 92 draws the end plate 81 towards the end plate 84, thus moving the stop 61 inwardly to reduce the throttle opening to a small value, if it is wide open, or to limit its opening. Suction is also applied to the clutch vacuum cylinder to disengage the clutch. When the solenoid H4 is energised, the pipes H0 and II 2 only are connected to suction, so that the intermediate plate 92 of the bellows 83 is displaced inwardly to open the throttle valve or prevent it from closing, and suction is applied to the clutch vacuum cylinder to hold the clutch disengaged, the bellows 82, and the chamber in the bellows '83, remaining connected to the atmosphere.

The bellows 82 and 83 may be replaced by cylinders, the stops 61 and 08 being secured to pistons slidable in the said cylinders.

Fi ures 10, 11 and 12 show the operating mechanism for the switch the switch itself, which is of the double pole type, being mounted on the steering column I2! of the vehicle. The operating plunger 522 of the switch is operated by cam strips I 23 secured to the gear-change rod 524, the cam strips being so positioned on the rod I24 that the plunger is depressed only when a gear is fully engaged. Zhe switch 6?. is mounted on a pipe clip I25 which is clamped onto the steerin column I2I, the pipe clip having secured to it two diametrically opposed ears I129, [2253. A bracket I2? clamped to the gear-change rod I20 carries a rocking arm i23, and two tension springs I29, I29 extend between the ears Q29 and the arm i253, the springs tending to urge the rod in either direction from a dead-centre position to hold it in a position corresponding to full engagement of any gear.

The contacts of the switch which are closed when the operating plunger 522 is depressed, are in the circuit of the solenoid lid, which circuit also includes contacts closed only when the clutch of the vehicle is disengaged. and its driving member is revolving at a lower speed than its driven member. The other contacts of the switch which are closed when the operating plunger I22 is free, are in the circuit of the solenoid H5. Therefore, when any gear is engaged and the clutch also is engaged, both circuits are open. The sequence of operations during gear changing is as follows. When the gear lever is moved to disengage the operating plunger 22 is released, and the circuit of the solenoid H5 is closed, causing the throttle stop 9"! to be moved inwardly, thus nearly closing the throttle if it is not already closed, and disengaging the clutch. The continued-movement of the gear lever .engages the. fresh gear, opening the previously closed contacts of the switch 62, and closing the contacts thereof in the circuit of the solenoid III. If the driving member of the clutch is revolving at a lower speed than the driven member, the circuit of the solenoid H4 is closed, and the throttle stop 63 is moved inwardly to speed up the engine until the driving member slightly overruns the driven member, the clutch being meanwhile held disengaged. When the driving member begins to overrun, the clutchcontrolled switch is opened, and the solenoid I I4 is tle-energised, thus allowing the clutch to engage, and the stop 68 to be withdrawn.

Figures 13 and 14- show a modified arrangement of the mechanism for operating the switch 62. The switch is secured to the steering column I2I by a two-piece clamp I36, and its operating plunger (22 is actuated by a lever I3I pivoted at I32 on the clamp. he lever lSI carries a roller I33 acting a cam follower, and the gear change rod carries five cams I34, I35, I35, I31 and I33 so placed t 1st the cams Iii-'l and I35 are engaged with the roller when the gear lever is engaged with the third and fourth gear shift bar, the cams I35 and are engaged with the roller when the gear lever is engaged. with the first and second gear shift bar, and the cam I38 is engaged with the roller when the gear lever is engaged with the reverse gear shift bar. Each cam has a notch such as those shown at I39 in Figure 13 to receive the roller when the corresponding gear is engaged, and the cams are individually adjustable on the rod I24.

Figure 15 shows a modified arrangement for connecting the IiOli8.l throttle control cable 1| to the throttle valve. The valve spindle 64 carries an arm I ll fixed thereto and supporting the pin 58 which (Io-operates with the throttle stops B1 and 68, those stops being operated by the bellows 82 and 83 as described with reference to Figure 7. The cable H is attached to another arm I4I which is free to turn on the spindle B4, and is engaged between the two arms of a somewhat U-shapcd leaf spring M2 fixed to the arm I43.

Thus the cable (I is normally able to operate the throttle valve through the leaf spring I42, but, if either stop or {it moved to limit the throttle valve movement, and the normal throttle control is held in a position to set the throttle to a position outside the limited range, the spring I42 can yield.

Only one stop may be provided, which is rendered operative to set the throttle valve within a predetermined range for all gear changes, or for changes in one direction only.

I claim:

1.ln a motor vehicle including an engine, throttle valve means for controlling the speed of the engine, a change-speed gearbox through which wheels of the vehicle are driven by the engine, means for engaging and disengaging the various gear ratios of the gearbox, and a friction clutch including driving and driven members between the engine and the gearbox, throttle control means including a driver operated throttle control member, means connecting said driver operated throttle control member to the throttle valve, a resilient connection in said connect- 5112 means enabling the throttle valve to move independently of the driver-operated throttle control member, a stop contacting member moving with the throttle valve, two movable stops cooperating with said stop-contacting member, one of said stops having an operativeposition in which it'limits the opening of the throttle valve and the other of said stops having an operative position in which it limits the closing of said throttle valve, stop actuating means for moving the first-mentioned stop to its operative position, separate stop actuating means for moving the second-mentioned stop to its operative position, said first stop actuating means being actuated by the gear engaging and disengaging mean to disengage any gear ratio, said second stop actuating means being actuated by movement of the gear engaging and disengaging means to engage a gear-ratio, and being subsequently returned from its operative position upon the attainment of synchronism between the driving and driven members of the friction clutch.

2. In a motor vehicle including an engine, throttle valve means for controlling the speed of the engine, a change speed gear box through which wheels of the vehicle are driven by the engine, and means for engaging and disengaging the various gear ratios of the gearbox, throttle control means including a driver-operated throttle control member, means connecting said driver-operated throttle control member to the throttle valve, a resilient connection in said connecting means enabling the throttle valve to move independently of the driver-operated throttle control member, a stop-contacting member moving with the throttle valve, a movable stop co-operating' with said stop-contacting member, a solenoid, an armature in said solenoid carrying said stop, a source of electric current, switch means for controlling the connection of said solenoid to said electric current source, said solenoid, when energized, moving the stop from a position in which it allows the throttle valve to move through its full range to a position in which it restricts the throttle valve movement to a limited range, and switch operating means actuated by the gear engaging and disengaging means to close the switch when the said means is operated to disengage any gear ratio.

3. In a motor vehicle including an engine, throttle valve means for controlling the speed of the engine, a change-speed gearbox through which wheels of the vehicle are driven by the engine, and means for engaging and disengaging the various gear ratios of the gearbox, throttle control means including a driver-operated throttle control member, means connecting said driver-operated throttle control member to the throttle valve, a resilient connection in said connecting means enabling the throttle valve to move independently of the driver-operated throttle control member, a stop-contacting member moving with the throttle valve, first and second movable stops co-operating with said stop-contacting member, said first stop having an operative position in which it limits the opening of the throttle valve and said second stop having an operative position in which it limits the closing of the throttle valve, a. first solenoid operatively connected to said first stop, a second solenoid operatively connected to said second stop, a source of electric current, first switch means controlling the connection of said first solenoid to the current source, second switch means controlling the connection of said second solenoid to the current source, and means operated by the gear engaging and disengaging means for selectively operating said first and second switch means respectively when said gear engaging and disengaging means is moved to effect a. change to a higher and a lower gear ratio.

4. In a motor vehicle including an engine, throttle valve means for controlling the speed of the engine, a change-speed gear box through which wheels of the vehicle are driven by the engine, means for engaging and disengaging the various gear ratios of the gearbox, and a friction clutch including driving and driven members interposed between the engine and the gearbox, throttle control means including a driver-operated throttle control member, means connecting said driver-operated throttle control member to the throttle valve, a resilient connection in said connecting means enabling the throttle valve to move independently of the driver-operated throttle control member, a stop-contacting member moving with the throttle valve, first and second movable stops co-operating with said stopcontacting member, said first stop having an operative position in which it limits the opening of the throttle valve and said second stop having an operative position in which it limits the closing of the throttle valve, a first fluid actuator operatively connected to said first stop to move it to its operative position, a second fluid actuator operatively connected to said second stop to move it to its operative position, a source of working fluid, valve means controlling the supply of working fluid from said source to said first and second fluid actuators and valve control means responsive to movement of said gear engaging and disengaging means and to synchronism between said driving and driven clutch members, said valve control means controlling the valve means to effect operation of the first fluid actuator when the gear engaging and disengaging means is moved to the neutral position, to effect operation of the second fluid actuator when the gear engaging and disengaging means is moved to engage a gear ratio, and to return said second actuator to its inoperative position when the driving and driven members of the friction clutch are synchronized.

5. In a motor vehicle including an engine, throttle valve means for controlling the speed of the engine, a change-speed gear box through which wheels of the vehicle are driven by the engine, means for engaging and disengaging the various gear ratios of the gearbox, and a friction clutch including driving and driven members interposed between the engine and the gearbox,

throttle control means including a driver-operated throttle control member, means connecting said driver-operated throttle control member to the throttle valve, a resilient connection in said connecting means enabling the throttle valve to move independently of the driver-operated throttle control member, a stop-contacting member moving with the throttle valve, first and second movable stops co-operating with said stop-contacting member, said first stop having an operative position in which it limits the opening of the throttle valve and said second stop having an operative position in which it limits the closing of the throttle valve, a first fluid actuator operatively connected to said first stop to move it to its operative position, a second fluid actuator operatively connected to said second stop to move it to its operative position, a source of working fluid, valve means controlling the supply of working fluid from said source to said first and second fluid actuators, solenoid means operating said valve means, a source of electric current, switch means operated by the gear engaging and disengaging means, and

switch means operated by the clutch, the switch means operated by the gear engaging and disengaging means operating the valve means to efiect operation of the first fluid actuator when the gear selecting means is moved to the neutral position and to effect operation of the second fluid actuator when the gear engaging and disengaging means is moved to engage a gear ratio, and the switch means operated by the clutch operating the valve means to return the second actuator to its inoperative position when the driving and driven members of the clutch are synchronized.

6. In a motor vehicle including an engine, throttle valve means for controlling the speed of the engine, a change speed gearbox through which wheels of the vehicle are driven by the engine, manually operated means for engaging and disengaging the various gear ratios of the gearbox, and a friction clutch including driving and driven members interposed between the engine and the gearbox, throttle control means including a driver operated throttle control member, means connecting said driver operated throttle control member to the throttle valve, a resilient connection in said connecting means enabling the throttle valve to move independently of the driver-operated throttle control member, a stop-contacting member moving with the throttle valve, first and second stops co-operating with said stop-contacting member, first and second fluid actuators, means connecting said first and second fluid actuators respectively to said first and second stops, a source of working fluid, valve means controlling the supply of working fluid from said source to said fluid actuators, solenoid means operating said valve means, a source of electric current, switch means operated by the manually operated gear engaging and disengaging means, and switch means operated by the clutch, the switch means operated by the manually operated gear engaging and disengaging means operating the valve means, when the said gear engaging and disengaging means is moved to the neutral position, to effect operation of the first fluid actuator and thereby position the first stop to limit the opening of the throttle valve, and operating the said valve means when the said gear engaging and disengaging means is moved to engage a gear ratio, to effect operation of the second fluid actuator and thereby position the second stop to limit closing of the throttle valve, and the switch means operated by the clutch operating the valve means when the speeds of the driving and driven clutch members are synchronized, to return the second actuator to its inoperative position.

SYDNEY MACDONALD PARKER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,891,678 Maybach Dec. 20, 1932 2,302,085 Wolfe et al Nov. 17, 1942 2,346,332 Rosenthal Apr. 11, 1944 2,387,370 Wallace et al. Oct. 23, 1945 2,396,231 Brill Mar. 12, 1946 2,421,496 Grieshaber et al. June 3, 1947 2,443,084 Rhodes June 8, 1948 2,474,316 May et al. June 28, 1949 2,500,580 Segsworth Mar. 14, 1950 2,519,080 Simpson Aug. 15, 1950 2,557,795 Price June 19, 1951

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