Abstract: A hydraulic control system for a four-wheel drive torque transfer mechanism for a vehicle, including an automatic transmission, a transfer mechanism having a two-wheel drive direct-coupling gear (H.sub.2), a four-wheel drive direct-coupling gear (H.sub.4) and a reduced-speed four-wheel drive gear (L.sub.4) and a hydraulic control circuit for controlling the transmission and the transfer mechanism. The transfer mechanism includes a reduction gear mechanism, a first output shaft, a second output shaft connected to the first output shaft by means of a linkage, a four-wheel drive clutch for rotatably connecting and disconnecting the first and second output shafts, a direct-coupling clutch for connecting and disconnecting the input shaft of the reduction gear mechanism and the first output shaft and a reduction brake for shifting the reduction gear mechanism into the reduced-speed mode.

Abstract: A fluid pressure actuator for a frictionally engaged unit of a vehicular transmission includes a first transmission and a second transmission coupled to the output side of the first transmission and provided with a speed step change mechanism which has a frictionally engaging element for engaging a rotary member to a fixed member in such a manner as to enable an optional disengagement between the rotary member and the fixed member.

Abstract: A main transmission has a transfer gear attached to its output shaft. The transfer gear provides two wheel high speed drive, four wheel high speed drive, and four wheel low speed drive. A control system controls the main transmission according to a detected speed mode of the transfer gear. The control system uses an electrical detector for sensing the speed mode of the transfer gear.

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.

Abstract: In a clutch mechanism for a power transmission system which effects engagement and disengagement between a central shaft and an outer peripheral shaft provided on the outer periphery of the central shaft, an improvement characterized by comprising splines provided on the outer periphery of the central shaft, and an inner tube of an annular clutch cylinder containing a piston of a fluid actuator and a clutch plate of a multiple disk clutch, the inner tube being fitted on the outer periphery of the central shaft through the splines.

Abstract: Described herein is a brake support mechanism particularly suitable for use in a 4-wheel drive auxiliary transmission to reduce the axial dimensions and to facilitate assembling of the transmission, the brake support mechanism essentially comprising: a transmission case; a cylindrical rotary member mounted in the transmission case; a multiple disk brake constituted by a combination of brake plates splined on the inner periphery of the transmission case and brake disks splined on the outer periphery of the rotary member; a center support fitted in the transmission case in a position adjacent the multiple disk brake; and a hydraulic actuator including an annular cylinder formed in the center support on the side of the multiple disk brake, a piston slidably fitted in the cylinder, an operating fluid supply passage formed in the center support, a return spring located on the outer periphery of the multiple disk brake and having one end thereof abutted against the transmission case, and a return spring mounting me

Abstract: An automatic transmission for motorcar of the type including a main transmission and an auxiliary transmission is disclosed. The auxiliary transmission has a plurality of speed changing stages and when it assumes a certain lower speed stage, any speed changing to higher speed stage is inhibited in the main transmission. The main transmission is provided with a solenoid valve which makes it possible to carry out speed changing to higher speed stage when it is turned on, while the auxiliary transmission is provided with a hydraulic control device which is communicated with a hydraulic servo via a hydraulic passage. The hydraulic servo is operatively associated with a speed reduction frictional engagement element which allows the auxiliary transmission to assume a certain lower speed stage.

Abstract: A transmission control device for controlling a transmission having main and sub transmissions in accordance with the state of running of a vehicle.The transmission control device having this constitution can control the main transmission on the basis of and in accordance with the transmission ratio of the sub transmission so as to optimize power efficiency, performance and fuel consumption in relation to the given ratio.

Abstract: A transmission control device for controlling the operation of a transmission system which has an automatic main transmission and a manually operable sub transmission. The shifting characteristics of the sub transmission are controlled in accordance with the level of the torque inputted to the sub transmission, so that the transmission as a whole exhibits a superior speed changing performance.

Abstract: A transmission control device for controlling the operation of a transmission system including a main transmission and a sub transmission comprises a control circuit adapted for effecting a change-over of the main transmission between different speed gears in accordance with the level of the torque output from an engine when speed modes of the sub transmission are changed over. It is therefore possible to allow the main transmission to select a gear conformable to the gear ratio set in the sub transmission in accordance with the engine output torque, whereby it is possible to obtain optimum shifting characteristics. In addition, it is possible to widen the shiftable region for the sub transmission.

Abstract: A hydraulic control system for an automatic transmission has an inhibitor valve which comprises a change-over valve having a first set position and a second set position and functioning to supply and discharge a hydraulic pressure to and from a hydraulic servomechanism for a friction engaging element through its movement between the first and second set positions; an arrangement for urging the change-over valve to the first set position; a plunger having a first set position and a second set position and functioning to bring the change-over valve into the second set position when the plunger is urged to the second set position. The inhibitor have functions to perform the supply and discharge of the hydraulic pressure to and from the hydraulic servomechanism in accordance with a first hydraulic signal and a second hydraulic signal through an arrangement which produces the first hydraulic signal for urging the change-over valve to the second set position and urging the plunger to the first set position.

Abstract: A hydraulic control system for an automatic transmission, including a pressure source, a regulator valve for regulating the oil pressure from the source, a first hydraulic servo for setting the transmission in a high speed position upon receipt of output oil pressure of the pressure regulator valve, and a second hydraulic servo for setting the transmission in a low speed position upon receipt of the output oil pressure, wherein the hydraulic control system comprises:a shift timing mechanism including a shift timing valve provided in a drain conduit of the second hydraulic servo and adapted to accelerate drainage of the second hydraulic servo in response to increases in supply oil pressure to the first hydraulic servo.

Abstract: The transmission control device of the present invention comprises a main transmission and a sub transmission and has a first hydraulic switching device which is controlled by automatic operation for setting the shift range of the sub transmission and a second hydraulic switching device which controls the hydraulic pressure produced by the first hydraulic switching device, prohibits any speed change of the shift range, and controls other functions of the sub transmission. By the above-described structure, the transmission control device of the present invention is able to prohibit speed changes in the shift range and to control other functions of the sub transmission regardless of the automatic operation of the sub transmission, because the second hydraulic switching device can control the hydraulic pressure produced by the first hydraulic switching device even if the shift mechanism of the sub transmission is being operated by the first hydraulic switching device.

Abstract: A transmission control device in accordance with the present invention for controlling a transmission system which is composed of a main transmission and a sub transmission, has a first rotational speed detector which is disposed on the input side of the sub transmission and a second rotational speed detector which is disposed on the output side of the sub transmission, and is characterized in that one rotational speed detector is employed while the sub transmission is in a speed changing state and the other rotational speed detector is employed while the sub transmission is not in a speed changing state, thereby performing system control.

Abstract: A lubricating system for a transmission of the kind having a driving shaft driven to rotate, a transmission shaft disposed parallel to the driving shaft, a chain for transmitting power from the driving shaft to the transmission shaft and a chain case enclosing the chain, the lubricating system comprising a chain chamber and an oil reservoir chamber in the chain case, the oil reservoir chamber having an upper inlet port for receiving oil from the chain chamber, at least some of the oil in the chain chamber being driven to reach the inlet port by movement of the chain, and the oil reservoir chamber having a lower outlet port for returning oil to the chain chamber, whereby oil flowing through the oil reservoir chamber may be cooled and the amount of oil in the chain chamber subject to agitation by the chain movement at any one time may be reduced, substantially prolonging the operational life of the lubricating oil.

Abstract: A hydraulic controller for transmission includes a brake and a clutch each of which corresponds to a different transmission ratio. An orifice control is provided in the conduit structure of the hydraulic circuit for actuating the clutch and brake such that a working oil quantity is varied in response to the engine throttle valve opening.

Abstract: A transmission system of the present invention which has a main transmission and a sub transmission includes a first output shaft speed detecting means for detecting the rotational speed of the output shaft of the main transmission and a second output shaft speed detecting means for detecting the rotational speed of the sub transmission. The thus arranged transmission system of this invention makes it possible to accurately detect the state of the main transmission by providing the first output shaft speed detecting means for detecting the rotational speed of the output shaft of the main transmission as well as the second output shaft speed detecting means for detecting the rotational speed of the output shaft of the sub transmission.

Abstract: A transmission control device for controlling the operation of a transmission which is composed of a main transmission portion and a sub transmission portion which is capable of manual change-over is disclosed. The control device inhibits the shifting operation of one transmission while the other transmission is in operation.This structure of the control device avoids the occurrence of synchronization of the shifts made by means of the main transmission portion and the sub transmission portion, and thereby eliminates the amplification of transmission shock caused by the synchronization of the shifts of the main transmission portion and the sub transmission portion, whereby optimum shifting characteristics are obtained.

Abstract: A transmission control system for an automatic transmission for a vehicle having a main transmission unit which provides a plurality of speed stages and an auxiliary transmission unit which is connected in series with the main transmission unit and provides two very different speed reduction ratios such as 1 and 3 such as desirable for a transmission selectively operative in a two wheel drive operational mode or in a four wheel drive operational mode, the auxiliary transmission being manually switched over between the two different speed reduction ratios, wherein there is provided a means for controlling the auxiliary transmission unit to override the manual control of the auxiliary transmission in a manner only to prevent switching over of the auxiliary transmission unit to the larger speed reduction ratio according to at least one parameter with regard to operational conditions of the vehicle and also according to which of the plurality of speed stages the main transmission unit is set.

Abstract: A control system for a 4-wheel drive transmission including a main transmission and an auxiliary transmission shiftable by operation of a hydraulic clutch for switching the mode of operation either to 2-wheel drive or 4-wheel drive including a manual changeover valve mechanically connected to a shift lever in a passenger's room of a vehicle for operating the hydraulic clutch according to the mode selected by the shift lever.