Abstract: A hydraulic control apparatus for controlling a hydraulically operated automatic transmission, having a speed sensor for detecting the speed of a rotary member which changes due to a shifting action of a frictionally coupling device. The apparatus includes a device for determining, based on the detected speed of the rotary member, that the shifting action of the coupling device is completed, and a device which is operated in the event of a failure of the speed sensor, for determining that the shifting action of the coupling device is completed when a time which has passed after the moment at which the need to effect the shifting action was determined or at which a shifting command to initiate the shifting action was generated exceeds a predetermined time interval. Upon determination of the completion of the shifting action, an electronic device terminates an operation to control the back pressure of an accumulator for adjusting the fluid pressure applied to the coupling device.

Abstract: A hydraulic control system for an automatic transmission has a shifting shock reducing device capable of regulating the transitional oil pressure applied to the frictionally engaging devices of the automatic transmission, and provided between a shift valve and the frictionally engaging devices. The shifting shock reducing device is controlled on the basis of a signal representative of the torque of the engine, and a signal representative of the transitional shift state to regulate the transitional oil pressure. Thus, the hydraulic control system is highly reliable, is capable of compensating for variations of the functions thereof over time, and is capable of maintaining a high control accuracy.

Abstract: A hydraulic hill hold control system for an automatic transmission for a vehicle adapted for the purpose of hill hold, wherein the supply of hydraulic pressure to the brake is interlocked with the shifting of the hydraulic speed stage switching system so that the brake is engaged only when the gear transmission mechanism is at a certain speed stage at which the brake is in any event engaged and therefore the engagement of the brake for hill hold does not interfere with the forward driving operation of the gear transmission mechanism.

Abstract: A transmission control device according to the present invention comprises a main transmission having a torque converting device provided with a direct clutch for effecting engagement and disengagement of the input member with output member of a torque converting portion; a sub transmission having a speed change mechanism; a drive-mode detecting means for detecting the drive mode of the speed change mechanism of the sub transmission; and a controller for controlling the lock-up characteristics of the direct clutch by means of the output of the drive mode detecting means.

Abstract: Described herein is a hydraulic control system for vehicular automatic transmission, including an accumulator back pressure control circuit which is provided between a line pressure conduit and a back pressure supply conduit, and comprises a first accumulator control valve for dropping the line pressure according to the throttle opening, and a second accumulator control valve receiving an input pressure commensurate with the throttle opening and dropping the output pressure of the first accumulator control valve according to the throttle opening to apply to the piston of the accumulator a back pressure varying in corresponding to the engine output shaft torque.

Abstract: A selecting valve is provided, which is switched by different signals sent out when the vehicle is stopped or when the vehicle is to start to move. The selecting valve is connected to a hydraulic servo unit for a forward clutch which is engaged to transmit torque when the vehicle is to move forward, and is supplied with line pressure and a control pressure provided by an electronically operated regulating valve, such as an electronically controlled throttle valve. The regulated control pressure from the electronically operated regulating valve is supplied to the hydraulic servo unit for the forward clutch when the vehicle is stopped, while line pressure is supplied when the vehicle is to move, thus preventing creeping and shift shock at starts. Since the selecting valve is provided with a port leading to the hydraulic servo unit for a brake which restricts vehicle movement, the brake can be applied when the vehicle is stopped and released when moved, thus providing hill-holding capability.

Abstract: In a system for shift control in an automatic transmission, wherein gear stages are automatically switched in accordance with a preset shift pattern, judgment is made as to whether or not a shifting was abnormal, and, if it is judged as abnormal, the shift pattern in the subsequent shifting is changed to a fail shift pattern, in which shift points are set slightly low. With this arrangement, the durability of frictionally engaging devices is secured.

Abstract: A supporting mechanism for a transmission shaft in an automatic transmission apparatus for use in a vehicle, wherein said shaft is rotatably supported at both end portions (1A), (1C) and at the intermediate portion (1B), and the amount of play of said shaft at said intermediate portion is set greater than those at the end portions, with a view to preventing oscillation of the shaft at the intermediate portion between the supporting points and favorably overcoming difficulty in assembly work, e.g., centering associated with supporting at three points.

Abstract: A vehicle automatic transmission includes a torque converter which has a rotational power output member, and also includes a gear transmission mechanism. This gear transmission mechanism includes; a friction engaging mechanism; first and second rotational power input members; a first clutch which selectively engages the torque converter rotational power output member to the first rotational power input member; and a second clutch which selectively engages the torque converter rotational power output member to the second rotational power input member.

Abstract: In a hydraulic control system for a vehicle transmission including a first throttle valve for producing a first throttle pressure for boosting a line pressure valve and a second throttle valve for producing a second throttle pressure for shifting speed stages of the transmission, the spools of the first and the second throttle valve are boosted by the first and the second throttle pressure supplied thereto, respectively, so as to reduce the force required for the driver to bias the two spools in parallel by stepping down on the accelerator pedal; the first and the second throttle valve are further supplied with the first and the second throttle pressure, respectively, in the feedback manner so as to attenuate the increase of the first and the second throttle pressure produced thereby; and a cut-back valve is provided to allow the supply of the first throttle pressure to the first throttle valve for the line pressure boosting and for the feedback control only when the vehicle is running at above normal speed.

Abstract: A vehicle automatic transmission includes a torque converter, and also includes a gear transmission mechanism. This gear transmission mechanism includes a manual range setting valve and a plurality of friction engaging mechanisms. Selective engagement of combinations of these friction engaging mechanisms, when the manual range setting valve is set to a forward range, causes the gear transmission mechanism to provide various forward speed stages. In this anti creep control method, a test is performed as to whether anti creep provision conditions hold, the anti creep provision conditions including whether or not the manual range setting valve is set to a forward range, and whether or not the vehicle is substantially stationary.

Abstract: An automatic transmission for an automotive vehicle is selectively operable either in a first mode of providing a first, a second next to the first and a third next to the second speed stages, or in a second mode of providing the first and the third speed stages while skipping the second stage. The upshifting from the first speed stage to the second speed stage according to the first mode is effected at a lower vehicle road speed than the upshifting from the first speed stage to the third speed stage according to the second mode for the same load on the engine of the vehicle.

Abstract: In a four wheel drive power transmission system for an automotive vehicle, including a planetary gear mechanism wherein the carrier, the ring gear and the sun gear thereof operate as a power input member, a first power output member for driving either of a pair of front wheels or a pair of rear wheels and a second power output member for driving the other of the pair of front wheels and the pair of rear wheels, respectively, the planetary gear mechanism being selectively locked to rotate as a unitary rotational member, a clutch is incorporated in a rotational power transmitting system for rotationally connecting the ring gear with either the pair of front wheels or the pair of rear wheels so as selectively to intercept the rotational power transmitting system between, wherein the first power output member provides hundred percent front or rear wheel drive when operated with the planetary gear mechanism being locked, while the second power output member provides high percentage opposite rear or front wheel dri

Abstract: A four wheel drive power transmission for a vehicle has a center differential device for distributing rotational power supplied from an engine to a front wheel propeller shaft and a rear wheel propeller shaft at a variable torque dividing ratio therebetween, and a mechanism for controlling the center differential device so as to vary the torque dividing ratio according to the magnitude of the torque of the rotational power supplied from the engine so that the torque dividing ratio is varied toward a decreased ratio for one of the front and rear wheel propeller shafts and an increased ratio for the other of the front and rear wheel propeller shafts as the magnitude of torque of the rotational power supplied from the engine increases. The torque loaded on one of the front and rear wheel propeller shafts is maintained not to exceed a determinate value as torque increases.

Abstract: A rotary cam assembly includes a support shaft provided on a fixed bracket, a cam follower supported on the bracket so as to be slidably displaceable, a plate cam the outer circumferential portion of which has a cam surface contacted by the cam follower, the plate cam being freely rotatably mounted on the support shaft at a center hole, a cylindrical member extending along the central axis of the support shaft and having one end connected to the plate cam via coupling means formed in the center hole of the plate cam, and an input member connected to the other end of the cylindrical member for rotating the plate cam.

Abstract: In a four wheel drive vehicle, this torque distribution device includes a friction engaging mechanism which controls drive torque distribution to the front vehicle wheels and/or to the rear vehicle wheels, and a servo device which receives an actuating hydraulic fluid pressure and which applies an engaging force to the friction engaging mechanism so as to cause it to be able to transmit torque. The engaging force for the friction engaging mechanism and the maximum torque transmission capacity thereof this provided both increase monotonically according to increase of the actuating hydraulic fluid pressure. This servo device includes first and second pistons which partially serve to define respective first and second pressure chambers, and which, when impelled by hydraulic fluid pressure in their respective first and second pressure chambers, both provide such engaging force for the friction engaging mechanism.

Abstract: A full time four wheel drive transmisson system for a vehicle includes a gear transmission mechanism, driven by an engine, which is automatically controlled to operate in any of several forward ranges of speed stages including a drive range and a set containing one or more intermediate hold ranges in which the engagement of at least one of the upper speed stages included in the drive range is prohibited. The transmission system also includes a central differential device, driven from the gear transmission mechanism, which provides rotational power to the combination of the front wheels of the automotive vehicle and to the combination of the rear wheels of the automotive vehicle while providing differential action between these combinations. The central differential device has a clutch which when engaged at least partly inhibits its differential action.

Abstract: A hydraulic servo for friction coupling devices of automatic transmissions, the hydraulic servo comprising: an annular drum including outer and inner cylinders and a side wall connecting the two cylinders together and mounted fixedly or rotatably within an automatic transmission case; an intermediate cylinder mounted concentrically in a predetermined position between the outer and inner cylinders of the drum; a return biasing means located between the intermediate and inner cylinders; and a connecting member securely connecting the return biasing means to a piston.

Abstract: In an automatic transmission, friction elements are engaged and disengaged by a hydraulic servo connected alternately to a pressure source or to a drain through a selector valve, and an accumulator is connected to the line between the selector valve and the servo. The resistance against the oil discharged from the accumulator, the resistance against the oil discharged from the servo, and the return biasing forces in the accumulator and servo are adjusted so that the hydraulic pressure at the servo is lower than the hydraulic pressure of the accumulator for a predetermined time when the selector valve connects the servo with the drain. In one embodiment, a relief valve responsive to a vehicle running condition, controls the discharge rate of working oil through the drain. In another embodiment, a pressure regulator varies the level of the pressure of the working oil discharged from the accumulator in response to variations in a vehicle running condition.

Abstract: A four-wheel drive automatic transmission primarily consisting of an automatic transmission having a transmission case, a transmission gear mounted in the transmission case and an automatic transmission hydraulic control unit including a transmission valve body secured to the bottom surface of the transmission case; and a four-wheel drive transfer having a transfer case, a transfer unit mounted in the transfer case and a transfer hydraulic control unit including a transfer valve body secured to the bottom surface of the transfer case. The automatic transmission hydraulic control unit and the transfer hydraulic control unit communicate with each other by oil passages cast in the transmission case and in the transfer case.