Abstract: An electronic transmission control system for a self-propelled off-road vehicle having an internal combustion engine and multiple gear powershift transmission controls the powershift transmission and provides the at least on control signal to the engine for selecting the speed at which the engine is to operate. The system preferably includes a first electronic controller that provides transmission control signals required to command the powershift transmission to shift to and operate in any particular one of its forward gears, and a second electronic controller that provides at least one engine control signal required to command the engine to operate at one of a number of different desired engine speeds and to monitor the actual engine speed.

Abstract: A diagnostic strategy for an automatic transmission having electronic shift control solenoids for controlling application and release of clutches and brakes during the establishment and disestablishment of torque ratios in multiple-ratio gearing for the transmission wherein provision is made for developing diagnostic data that detects failure modes due to a faulty shift solenoid by using predetermined failure modes stored in the RAM portion of a microprocessor and comparing those known failure modes to the actual performance of the shift solenoids.

Abstract: A method and apparatus for transmission shift control and prevention is provided. When the inching pedal is not depressed, the transmission is free to shift to the desired gear. When the inching pedal is depressed, the transmission is free to shift to the desired gear if the shift is a shift from a gear into neutral. With the inching pedal depressed and the shift lever moved from neutral into a gear, the transmission is free to shift if the transmission speed is below first gear high idle. When a directional shift has been requested, the transmission is free to shift to the desired gear if the transmission speed is below first gear high idle.

Abstract: A diagnosing apparatus for diagnosing a vehicle automatic transmission system including an automatic transmission having frictional coupling devices, and solenoid-operated valves for controlling the frictional coupling devices to shift the automatic transmission according to shift commands generated by a control device, the apparatus including a speed detector for detecting an engine speed of the vehicle, a device for determining a reference range of the engine speed within which the engine speed is expected to fall when the transmission is placed in a position selected by a shift command, a device for determining whether a predetermined running condition of the vehicle is satisfied, and a defect detector for determining whether there exists a defect associated with the automatic transmission system, depending upon whether the detected engine speed is held within or outside the determined reference range when the predetermined vehicle running condition is satisfied.

Abstract: A control method/system for controlling engagement of a target gear ratio (GR.sub.T)in a vehicular automated mechanical transmission system (10) is provided. The control causes engine speed (ES) to be alternately greater than and then less than synchronous engine speed (ES=IS=OS*GR.sub.T) to cause torque reversals across the engaging positive jaw clutch associated with the target gear ratio to minimize or prevent partial engagement caused by torque lock conditions.

Abstract: A control system and method for a semi-automatic mechanical transmission system (10) is provided for allowing operator request for a direct downshift or upshift into a preselected start ratio, under certain predefined conditions. The preselected start ratio is that ratio actually utilized in the immediately preceding vehicle start from stop operation.

Abstract: A control system (104)/method for a vehicular automated mechanical transmission is provided, which will compare input signals indicative of input shaft speed (IS) to the product of input signals indicative of output shaft speed multiplied by engaged gear ratio (OS*GR) to develop control parameters indicative of drivetrain torque magnitude and/or phase requiring a driveline torque transducer.

Abstract: An automatic transmission of a vehicle including a speed change gear mechanism including rotary members such as gears and gear carriers and hydraulically operated friction engaging means and adapted to provide various speed stages according to selective engagement and disengagement of the friction engaging means is controlled by such steps as detecting rotation speed of at least one of the rotary members during a shifting between the speed stages, changing hydraulic pressure of at least one of the friction engaging means during a first phase of the speed stage shifting so as to make the rotation speed of the one rotary member follow a first change performance curve calculated according to a first feedback control program, and changing the hydraulic pressure of the one friction engaging means during a second phase of the speed stage shifting so as to make the rotation speed of the one rotary member follow a second change performance curve calculated according to a second feedback control program in continuity

Abstract: A downshift control for a manually shifted transmission (10) is provided. The control senses vehicle ground speed (100) and compares same to predetermined maximum values (REF.sub.1, REF.sub.2) at which certain ratios are allowed to downshift engaged. If vehicle speed exceeds the reference (OS>REF), a blocking plunger (216) assumes a position (216B, 216C) wherein selection of the prohibited ratio(s) is automatically mechanically blocked.

Abstract: In the present invention a solenoid is used on a ratchet shifter and is controlled through a relay by an electronic controller. This controller can be an analog, digital, or microprocessor driven device. The power supplied to the solenoid most conveniently is the existing battery of the vehicle. This power source is the only source needed, unlike pneumatic cylinders that require a bottle of compressed gas, e.g., air or CO.sub.2. The electronic controller is reset when the hold button is activated at the starting line. When the hold button is released, the vehicle launches violently at or above the rpm lock up of the transmission converter. This is sometimes referred to as "converter flash". If the rpm lock up of the converter is close to the rpm level setting for the first shift, or tire spin occurs, the rpm level will be reached prematurely causing the vehicle to shift early. The electronic controller has a preset time delay, disabling a shift, that begins when the hold button is released.

Abstract: The transmission is of a type that a low-speed transmission train is established in cooperation with one-way clutch. A high-speed transmission train is established by hydraulic oil supply via a shift valve in a condition in which the hydraulic oil is kept supplied to the low-speed hydraulic engaging element. A pressure adjusting valve and a hydraulic oil pressure control valve control, to increase or reduce, the supply pressure of the hydraulic oil to the high-speed hydraulic engaging element. A speed change controller at an initial stage maintains the shift valve, at the time of speed changing from a high-speed transmission train to a low-speed transmission train, in a condition in which the hydraulic oil is supplied to the high-speed hydraulic engaging element. The supply pressure of the hydraulic oil is reduced in this condition until the high-speed hydraulic engaging element gives rise to a slip.

Abstract: In a non-stage transmission control system, the output current instruction signal of a microcomputer is provided as a pulse-width-modulated signal, with a result that the number of signal lines from the microcomputer is reduced. Furthermore, the current feedback signal of a solenoid is applied to the microcomputer, for detection of abnormal conditions, and a quick break resistor is connected in series to a feedback diode to increase the current reduction rate of the solenoid.

Abstract: An apparatus is provided for use in a vehicle having an engine driven transmission which includes a plurality of gear ratios. The apparatus includes a sensor adapted to sense an operating parameter and responsively produce a parameter signal. A memory device includes a custom shiftpoint map for storing data which relates transmission gear ratio to the parameter signal. A programming device for allowing the custom shiftpoint map to be reprogrammed during vehicle operation. A controller is adapted to receive the vehicle speed signal, retrieve data from the custom shiftpoint map, and process the retrieved data and the parameter signal to produce a transmission control signal. An actuator is adapted to receive the transmission control signal and responsively control the transmission gear ratio.

Abstract: In a tractor transmission system having electro-hydraulically actuated powershift clutches and a forward/reverse coupler mechanically coupled to a forward/reverse lever, a dump button is provided on the lever for releasing powershift clutch pressure. The forward/reverse coupler is uncoupled from the transmission input and output shafts when the button is depressed. An operator may shift between forward and reverse gears by depressing the button and shifting the lever. Upon release of the dump button, a microprocessor performs a control algorithm during which it senses engine speed and ground speed, computes acceleration/deceleration, and controls the clutch pressure of one of the powershift clutches to provide smooth acceleration in the direction selected by the shift lever. The arrangement is particularly suited for shuttle shift (forward/reverse) operations but may be used to provide smooth acceleration from a stopped position.

Abstract: An improved shifter assembly useful in a multi-geared vehicle equipped with an in-line shifter having a front, a rear, an upstanding shift handle, and a cover which is attached to the vehicle by a housing attachment and which shifts the vehicle forward gears in a forward or reverse pattern with a shifter assembly. The improved shifter assembly includes a bracket mounted to the in-line shifter and attached to the vehicle by the housing attachment while the cover is in position; and an actuatable rod and piston assembly attached to the bracket and to the shift handle of an in-line shifter with shifter handle arc accommodation.

Abstract: A reengagement control system/method (200) for a semi-automatic mechanical transmission system (104) of the type requiring manual synchronization of the transmission to enable automatic implementation of a selected shift into a target gear ratio is provided. The reengagement control will cause immediate engagement of an engageable ratio, based upon vehicle speed, if the transmission is shifted to neutral and is then unable to engage in the target gear for greater than a predetermined time (REF.sub.2) as vehicle acceleration (dOS/dt) exceeds an acceleration reference value (REF.sub.1).

Abstract: A control system for sensing unintended range section (14) not-engaged conditions in an automated mechanical range-type compound transmission (10), and for causing engagement of the selected range section ratio (86, 88), is provided.

Abstract: A control system (104)/method for semi-automatically executing automatically and manually selected upshifts and downshifts of a mechanical transmission system (10) is provided. The control system includes a central processing unit (106) for receiving input signals indicative of transmission input shaft (16) and output shaft (90) speeds and from a driver control console (108) and processing the same in accordance with predetermined logic rules to issue command output signals to a transmission actuator (112, 70, 96) to implement the selected shifts. The control is effective to initiate a shift by automatically preselecting a shift from the currently ratio into neutral and to then await a manually caused torque break of the transmission to complete the shift to neutral. The control is effective to minimize wear by issuing repetitive shift prompts if transmission neutral is not sensed within predetermined times from preselection of a shift frown a currently engaged ratio (GR) into neutral(N).

Abstract: A control system/method (104) for controlling execution of selected shifts of a mechanical transmission system (10) is provided. The control system includes a central processing unit (106) for receiving input signals indicative of engine or input shaft (11/98) speeds and of output shaft or vehicle speed (VS) speeds and from a driver control console (108) indicative of manual or automatic selection of upshifts or downshifts from a currently engaged gear ratio and processing the same in accordance with predetermined logic rule to issue command output signals to a transmission actuator (112, 70, 96) to implement the selected shifts upon a manually or automatically caused torque break of the transmission and manually or automatically caused substantial synchronization of the transmission thereafter. The predetermined logic rules include a strategy for sensing conditions indicative of a potentially dangerous downhill free-wheeling situation and for immediately causing the forced engagement of a gear ratio (GR.sub.

Abstract: A manually-shifted synchronized compound transmission (10) is provided with a relatively simple and inexpensive mechanism for warning the operator that an inappropriate gear ratio has been selected. Sensors (110, 112, 114) provide input signals (116) to a logic unit (118) indicative of the rotational speed of the transmission input shaft (118) and the logic unit will issue command signals (120) to an alarm member (122) if sensed input shaft speed is not within an acceptable range to warn the vehicle operator that reengagement of the vehicle master clutch (C) in the currently engaged ratio (GR) will result in undesirable overspeeding and/or underspeeding of the vehicle engine (E).

Abstract: A control method/system is provided for controlling start from stop shifting operations of a vehicular semi-automatic transmission system (10) of the type automatically implementing selected gear changes of a mechanical change gear transmission (12) and requiring manual operation (3) of the vehicle master clutch (16) in start from stop conditions is provided. During engagement of a selected start ratio, the system controller (38) monitors for gear butt conditions and will warn the operator if such conditions are sensed.

Abstract: An automated transmission (10) system having a selectable automatic shift initiation mode of operation (D) is provided with manually operated selectors (226/228) for selectively increasing and decreasing the engine speeds (240, 242) at which upshifts and downshifts are implemented in the automatic shift initiation mode of operation.

Abstract: A method and apparatus for selecting a transmission starting gear based on calculated gross vehicle weight is disclosed. The vehicle speed and grade are monitored by sensors which provide data to a computer. The computer is programmed to calculate vehicle acceleration from the sensed speed and to adjust the acceleration value so as to eliminate the effect of grade. The gross vehicle weight is then calculated from the adjusted acceleration value. Based on the calculated gross vehicle weight and the existing grade, an appropriate starting gear is automatically selected by the computer from a look-up table stored in memory.

Abstract: In an apparatus for controlling an automatic transmission for a vehicle in which, at the time of gear engagement due to changing over from a reverse range or a neutral range to a forward range, a speed-change stage of the automatic transmission is shifted down to a low-speed stage after once setting it to a predetermined high-speed stage. The apparatus has a detector for detecting an amount of slippage of high-speed stage engaging elements which establish the high-speed stage and a control device for controlling to shift down, at the time of gear engagement, to the low-speed stage after the amount of slippage of the high-speed stage engaging elements has lowered to a predetermined value or smaller.

Abstract: A system and method are disclosed for controlling a shift event in a transmission wherein a shift actuator develops a force to effect the engagement of a clutch collar and a gear. The method comprises detecting when a non-fully engaged condition of the clutch collar and the gear occurs, indicating either a tooth butt or torque lock condition, and then pulsing the shift actuator, when the non-fully engaged condition is detected, between a relatively low force and a relatively high force to disturb the clutch collar and the gear out of the non-fully engaged condition. The detecting step comprises examining either the axial position of the clutch collar or the axial position of a shift rail operatively connected to the clutch collar with a rail position sensor. Preferably, a signal having a modulated pulse width and a frequency of between about 5 and 20 Hertz is sent to the shift actuator.

Abstract: A speed change control and apparatus of an automotive automatic transmission causes a turbine rotational speed to change toward a synchronous rotational speed associated with a desired gear stage by engaging a connection-side clutch while disengaging a release-side clutch, to thereby carry out gear-changing. To reduce a speed change shock, a speed change time is rendered stabilized irrespective of vehicle running state, by carrying out feedback control such that the time-dependent change rate (Ns)' of a rotational speed difference between clutch plates and clutch discs of the connection-side clutch becomes equal to a target slip rotational speed change rate (Ni)'.

Abstract: A powershift transmission includes a plurality of clutches, including a final or directional set of clutches. The clutches are controlled by electro-hydraulic direct acting valves and two electro-hydraulic proportional or pressure modulating valves. The pressure modulating valves modulate the pressure supplied to the direct acting valves associated with the three directional clutches. Vehicle deceleration during a shuttle shift is achieved by releasing (unpressurizing) all clutches, then gradually pressurizing only two clutches in the final or directional set.

Abstract: A pneumatic control system (200) for controlling the automated shifting of the splitter section (114) of an automated compound transmission (110) is provided. Shifting of the splitter section is controlled by a differential area piston/cylinder actuator assembly (162) having a first chamber (168A) associated with low-speed operation and a second chamber (170A) associated with high-speed operation. Pressurization and exhaust of each of the chambers is controlled by an individual independently controlled solenoid actuated valve (202 and 204 respectively), each of which operates in response to control signals from an ECU 124.

Abstract: A fault tolerant method of gear selection which initiates a gear selection search in response to a gear upshift or downshift requirement in an attempt to locate a gear that, if used, would result in an engine speed between both upper and lower engine speed limits. The search progresses from the lowest to the highest gear in the case of an upshift requirement and from the highest to the lowest gear in the case of a downshift requirement.

Abstract: An electrically actuated shifting mechanism includes a reversible rail select electric motor and a reversible in-gear electric motor. Three groups of switches are provided to effect one-at-a-time operation of the motors with a center group of switches being used to effect operation of either the rail select or the in-gear motor and to determine the direction of operation of the motor. In one embodiment of the invention, the motor control circuitry also controls the operation of a main clutch motor. Four groups of switches are used to effect operation of the in-gear, rail select and clutch motors in desired directions. Pulse width modulation is used to effect simultaneous and out-of-phase operation of the in-gear and main clutch motors.

Abstract: A control method/system (200) for a control system (104) for semi-automatically executing automatically selected upshifts and downshifts of a mechanical transmission system (10) is provided. The control system includes a central processing unit (106) for receiving input signals indicative of transmission input shaft (16) and output shaft (90) speeds (IS, OS) and processing the same in accordance with predetermined logic rule to issue command output signals to a transmission actuator (112, 70, 96) to implement the selected shifts by automatic shifting into neutral upon a naturally or manually caused torque reversal of the transmission and remaining in neutral until the vehicle operator causes substantially synchronous conditions to occur.

Abstract: A system and method for reducing wheel spin of a vehicle on slippery surfaces wherein the wheel spin is reduced by regulating the engagement of the clutches in a multiple clutch transmission of the vehicle. Upon detection by a controller of an abrupt acceleration by a driven wheel, the controller partially engages the transmission clutch which is currently disengaged, thus increasing the load on the engine and reducing the wheel spin while maintaining the drive train torque path through the previously engaged transmission clutch. Additionally, engine output is decreased upon detection of wheel spin to reduce the wear on the partially engaged clutch.

Abstract: A transmission having engagement mechanisms which employ an engagement inner having cam surfaces forming the race thereof, an engagement outer having a circular outer race and rollers therebetween. A cage mechanism angularly positions the rollers such that they may be wedged between the cam surfaces and the outer race so as to interlock the engagement inner and outer. Actuator mechanisms are employed which are axially movable to engage and angularly position the cages relative to the engagement inner for controlling the engagement mechanism. A plurality of control systems both electronic and mechanical control the operation of the engagement mechanism so as to require substantially synchronous movement between engaging elements. Alternately, nonsynchronous shifting may be accomplished under power for power or rapid shifting. Clutch inhibit may also be employed to prevent premature reengagement of the clutch before shift complete.

Abstract: A system for controlling the selection of the operative ratio of a vehicle powershift transmission driven from an engine via a main clutch. The system includes a clutch status sensor for sensing engaged and disengaged conditions of the main clutch. A selector is provided for selecting the operative ratio of the transmission. Also, a control circuit is provided which includes a ratio-change modulating function which, when the main clutch is engaged and a change to a non-adjacent ratio is selected, invokes a serial routine which ensures that each intermediate ratio between the current ratio and the selected ratio is engaged for a moment to ensure a smooth substantially jerk-free progression between the current ratio and the selected ratio. When the main clutch is disengaged and a change to a non-adjacent ratio is selected, the control circuit invokes a direct routine which permits changes from a current ratio to a non-adjacent selected ratio without engagement of any intermediate ratio.

Abstract: A multi-speed mechanical automatic transmission has two planetary gear trains, each including a sun gear, planet gears mounted in a planet carrier, and a ring gear. The first planetary gear train provides low gear and direct drive; the second train modifies low gear operation of the first train to provide an intermediate gear operation. The first sun gear is fixed to an input shaft, and the first planet carrier drives an output shaft. The second planet carrier is coupled to rotate the first ring gear in one direction, and free wheels or selectively actuated friction brakes prevent rotation of the first and second ring gears in the opposite direction. The first planetary train has helical gears, and a direct drive clutch selectively couples the first ring gear to the first planet carrier.

Abstract: An automatic range shift control system for automatically controlling range section (14) shifting in an otherwise manually shifted range type compound transmission (10) is provided. A sensor (100) senses a value indicative of vehicle ground speed and provides a signal (100A) which is compared to a reference value. If the signal is greater than the reference, an actuator (96) is urged to engage the high speed range ratio and if the signal is less than the reference, the actuator is urged to engage the low speed range ratio.

Abstract: A control system (104) for controlling execution of selected upshifts and downshifts of a mechanical transmission system (10) is provided. The control system includes a central processing unit (106) for receiving input signals indicative of engine (11) and output shaft (90) speeds and from a driver control console (108) indicative of manual or automatic selection of upshifts or downshifts from a currently engaged gear ratio and processing the same in accordance with predetermined logic rule to issue command output signals to a transmission actuator (112, 70, 96) to implement the selected shifts upon a manual or automatic caused torque break of the transmission and manual or automatic substantial synchronization of the transmission thereafter. The predetermined logic rules include an algorithm providing enhanced recovery from a missed shift and stuck in neutral condition including rules for selecting a more easily engaged ratio (GR.sub.MSR) in view of current engine speed (ES.sub.

Abstract: In a powershift transmission system the output shaft and driveline unwind and then wind up during shifting under load as the torque applied to the shaft through a first clutch is reduced and the torque applied to the shaft through a second clutch is increased. The degree of winding or unwinding is dependent on the load being driven by the shaft and is manifested as an apparent increase or decrease in the rate of rotation of the output shaft as measured at the transmission end of the shaft. The rate of rotation of the transmission output shaft is sensed during shifting and the second clutch pressure is controlled in accordance with the sensed rate of rotation so that the second clutch pressure varies according to the load. The arrangement reduces sudden accelerations under no-load conditions but permits near optimum clutch pressures at heavier loads.

Abstract: An auxiliary transmission section (14) shift control system (230)/method is provided which include a residual pressure valve (246) and a one-way restricted flow pressure relief valve (250) to prevent an auxiliary section high speed ratio synchronized clutch (92) damage if the main transmission section (12) is engaged during an auxiliary section upshift. The chamber (224A) of the actuator (220) associated with the high speed synchronizer clutch is constantly gradually vented to a reference pressure through a severely restricted orifice in the one way restricted flow pressure relief valve (250) and the residual pressure valve (246) will block fluid flow from the source (234) to the slave valve (238) whenever the main transmission section is shifted to the not neutral condition thereof.

Abstract: An electronically controlled transmission in which a shift actuator for driving a sleeve of a roller synchro mechanism and a throttle actuator for an engine are electronically controlled. The shift actuator is comprised of a drum type actuator of a simple structure comprising a shift drum and a shift fork. The use of the roller synchro mechanism ensures that only a small driving force for the shift drum is required, which makes it possible to provide a reduction in size of the shift actuator. In addition, a shift lever for operating a shift switch for producing the shifting instruction signal is mounted on either left or right side of the steering wheel. This ensures that the shifting-up and shifting-down signals can be produced by one of the driver's hands, leading to an improvement in operability of the shift lever.

Abstract: Shift control system (300)/method for a splitter type auxiliary section (14/102) is provided which includes control members (328) to prevent auxiliary section synchronized clutch (92, 136) damage if the master clutch (C) is engaged during an auxiliary section shift. Upon sensing master clutch engagement during a shift into the auxiliary section high-speed ratio, the force is used to engage the high speed ratio is reduced from a first (p*a.sub.224) to a considerably lower second (p*a.sub.224 -a.sub.222)) level.

Abstract: An auxiliary transmission section (14) shift control system (230) method is provided which includes control members (246) to prevent auxiliary section synchronized clutch (92, 128) damage if the main transmission section (12) is engaged during an auxiliary section shift. Upon sensing (254, 256) synchronized jaw clutch assembly blocked position during a shift into the auxiliary section high-speed ratio, the force used to engage the high speed ratio is gradually reduced from a first (p*a.sub.224) to a considerably lower second (p*(a.sub.224 -a.sub.222)) level.

Abstract: A shift valve (312) assembly for an auxiliary transmission section (14) shift control system (300)/method is provided which will prevent auxiliary section sychronized clutch (922, 128) damage, and will complete the auxiliary section shaft, if the main transmission section (12) is engaged during an auxiliary section shift into high speed ratio thereof.

Abstract: A transmission for a vehicle comprises a mechanical stepped gearbox (6) in front of which a hydraulic torque converter (5) is arranged. The torque converter (5) comprises a turbine wheel (19) which is connected to a turbine shaft (21). An input shaft (25) of the gearbox (6) is connected in a drive power-transmitting manner to the turbine shaft (21). In addition, a brake (34) is connected to the turbine shaft (21) or the input shaft (25), in which respect, on starting-up, the input shaft (25) can be stopped in order to permit engagement of a starting gear without the need to produce drive power interruption by means of a conventional clutch. The brake (34) is also used when changing-up for synchronization of the gearbox (6) together with an electrical control unit (32) for engine regulation. This allows the gear-changing in a mechanical, unsynchronized stepped gearbox to be carried out in a simple manner.

Abstract: A manual speed selector of an automatic vehicle transmission in which a line pressure is supplied from a manual valve capable of being changed over a shift lever to control solenoid valves so as to selectively supply hydraulic pressure to frictional engagement devices by shift valves. The shift lever can be moved between an automatic shift mode position and a manual shift mode position, and a transitive position is provided between these two mode positions. At the transitive position, the manual valve is set in a position such as to enable supply of hydraulic pressure, and the transmission can be set in a neutral state by controlling the solenoid valves. If the preceding shift lever position is neutral, the neutral state can be maintained or, when the shift lever is in the transmissive position, the neutral state can be set according to the time for which the shift lever is continuously placed in the transitive position and to the vehicle speed.

Abstract: A shift control method/system for shifting an automated compound range type transmission (14) in only the auxiliary section (96) to provide a limp-home function if system faults adversely effecting continued main section (94) shifting are detected is provided.

Abstract: A control method/system for an automated mechanical transmission system 12) including a nonsynchronized transmission (14) is provided with logic rules for detecting and responding to conditions indicative of jaw clutch tooth (98 a/b, 114 a/b, 118 a/b, 120 a/b, 128 a/b butt. and/or tooth buzz.

Abstract: An automatic transmission having a plurality of driving gears which are individually and selectedly placed in driving engagement with a drive shaft dependent upon the speed of rotation of the drive shaft. The method of automatically engaging and disengaging the drive coupling between a drive gear and the drive shaft is such as to permit the drive shaft to free wheel whenever the rotation of the drive gear is retarded or stopped. The releasable coupling is achieved by centrifugally actuated pawls which selectedly engage in detent notches about the inner diameter of the drive gears and which pawls automatically retract and disengage from these notches when the drive gears are retarded or stopped.

Abstract: A shift control system for an automatic transmission comprises: a gear train including a plurality of planetary gear sets having rotary components, an input shaft and an output shaft; a plurality of clutches for selectively connecting either the rotary components of the planetary gear sets with each other or the rotary components and the input shaft; and a plurality of brakes for holding the rotary components selectively in immovable states, any one of the planetary gear sets being adapted to take no part in the transmission of torque at one gear stage.

Abstract: An operation apparatus for a vehicle automatic transmission mechanism includes first and second actuators, connected in parallel with a hydraulic valve, for driving the hydraulic valve to switch a travel range of an automatic transmission mechanism, a control unit for controlling the first and second actuators, and a transmission operation unit for outputting a range signal indicating a presently set travel range to the control unit. The transmission operation unit includes a stroke contact type operation switch on which travel ranges to be set are sequentially aligned along a predetermined path.