Abstract: A method of controlling a transmission of a vehicle selectively either in a first mode of operation in such a manner that the transmission is shifted among a plurality of speed stages according to a first shift pattern, or in a second mode of operation in such a manner that the transmission is shifted among those speed stages which lacks at least one intermediate speed stage in the above-mentioned plurality of speed stages according to a second shift pattern, according selection between the above two modes of operation. On-off controlling of a lockup clutch is also changed in two modes according to the selection between the two modes of speed stage shifting, when it is incorporated in the transmission.

Abstract: A hydraulic circuit for controlling an automatic transmission. The hydraulic circuit has a control valve connected between a shift valve and a hydraulic servomotor for actuating a frictional engagement element such as a brake in a main transmission unit. The control valve is controlled by a signal from a control means in such a manner that, when the hydraulic servomotor is drained by the operation of the shift valve to disengage the brake, the engagement of a frictional engaging element in another transmission unit is synchronized therewith.

Abstract: A rotational speed detecting device for detecting the rotational speed of a predetermined element of a shifting unit is provided for at least one of a main shifting unit and a sub-shifting unit. A control is provided for controlling a predetermined friction engaging element of at least one of the shifting units according to signals from the rotational speed detecting device, so that shifting operations of both the shifting units will be synchronized when both the units are shifted. Therefore, the output of speed of the transmission is not temporarily increased or decreased and thus, smooth shifting is obtained.

Abstract: A cut-back pressure control device for a multi-speed automatic transmission includes a cut-back valve that has a spool which is controlled by both hydraulic pressure which changes in response to shifting of a sub-transmission unit between high-speed and low-speed modes and a hydraulic pressure which is established by the operation of the main transmission unit at 2nd or higher speeds. The spool is moved to a position where it interrupts the cut-back pressure when the main transmission unit selects the 1st speed while the sub-transmission unit is in the low-speed mode, whereas, when the sub-transmission unit is in the high-speed mode or when the main transmission unit selects the 2nd or a higher speed, the spool is held at a position at which it permits the supply of the cut-back pressure.

Abstract: In an assembly for a vehicle of an engine and a four wheel drive power transmission system including a speed change device, a first power distribution device for distributionally dividing rotational power toward a pair of front wheels and a pair of rear wheels and a second power distribution device for rotationally dividing rotational power for the pair of either the front wheels or the rear wheels, wherein the engine, the speed change device and the first power distribution device are assembled in this order along a common central axis with one of two output shafts of the first power distribution device being shifted sideward of the central axis and directed toward the engine while the second power distribution device is mounted to a side of the engine with an input shaft thereof being directed toward and substantially aligned with the above-mentioned output shaft of the first power distribution device, a propeller shaft to connect the above-mentioned output shaft of the first power distribution device by a

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: Described herein is a hydraulic servo drum which is compact in construction and defines an appropriate area for a piston, the servo drum including: an annular plate member having a press-formed cylindrical portion around the outer periphery thereof; an intermediate cylinder member having one end thereof fitted on the cylindrical portion of the annular plate member and formed with a spline in the remaining portions; and an outer cylinder member provided with a folded portion at one end thereof and having the inner periphery of the folded portion connected to the intermediate cylinder member.

Abstract: An oil pass for communicating a hydraulic servo a change-over valve is provided with an orifice and a by-pass disposed parallel to one another. The by-pass is provided with a sequence valve. When the hydraulic servo is subjected to less than a predetermined pressure, the sequence valve communicates to the change-over valve and the hydraulic servo through the by-pass, and when the hydraulic servo is subjected to a pressure that is higher than the predetermined pressure, the sequence valve is cut off.

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: An accumulator control device for controlling the back pressure of an accumulator includes an accumulating control valve having a first port communicating with a control oil source and a second port communicating with an accumulator back pressure chamber. The accumulator control valve is controlled by a oil pressure from a shift control. According to the control position of the shift control, the accumulator control valve controls the communicating state of the first and second ports to increase or decrease the back pressure of the accumulator.

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: In an assembly for a vehicle of an engine and a four wheel drive power transmission system including a speed change device, a first power distribution device for rotationally dividing rotational power for the pair of either the front wheels or the rear wheels, wherein the engine, the speed change device and the first power distribution device are assembled in this order along a common central axis with one of two output shafts of the first power distribution device being shifted sideward of the central axis and directed toward the engine while the second power distribution device is mounted to a side of the engine with an input shaft thereof being directed toward and substantially aligned with the output shaft of the first power distribution device.

Abstract: A direct coupling clutch being assembled within a casing of a fluid coupling having an impeller mounted on the casing and a turbine supported on an output shaft of the fluid coupling. The direct coupling clutch includes a piston mounted slidably on a turbine hub in axial direction for engaging with and disengaging from a front cover of the casing and a damper device resiliently connecting the turbine hub and piston. The damper device includes an annular driven plate consisting of two guide plates secured concentrically with each other and having a first set and a second set of spaces arranged in double rows along two concentric circles, an annular drive plate having a set of openings arranged in a row along a first circle, a set of projections arranged in a row along a second circle, a first coil spring inserted in each of the first set of spaces and within each of the set of openings and a second coil spring inserted in each of the second set of spaces and between the projections.

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 support mechanism for friction coupling devices in an automatic transmission is disclosed.A snap ring is mounted on a stationary or rotational member in an automatic transmission case and adapted to receive the operational load of one friction coupling device through an annular plate member.A stepped portion is formed on the stationary or rotational member and adapted to receive the operational load of another friction coupling device through the annular plate member.

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: In a four wheel drive power transmission system for a vehicle, a power distribution device receives rotational power from an engine and provides rotational power to the combination of the front wheels and also to the combination of the rear wheels, and is controllable either to provide differential action between the front wheels combination and the rear wheels combination, or for this differential action to be at least partially inhibited by torque transmission. This slippage control device includes: a subsystem which estimates the torque being input to the power distribution device for four wheel drive from the transmission mechanism; and a subsystem which provides differential action inhibition of the power distribution device according to the thus estimated value of the torque being input to it from the transmission mechanism. The method of operation of this device is also described.

Abstract: An automatic transmission, for a vehicle with an engine, includes a hydraulic fluid pump which supplies pressurized hydraulic fluid. It is detected whether or not the engine is being started, and the pump output is controlled so as to be decreased when the engine is being started. If the pump is one whose output per one revolution of its input member is variable, then its output may be thus controlled by decreasing its output per one revolution when the engine is being started. And, if the pump is a variable capacity type vane type hydraulic fluid pump the output of which per one revolution of its input member is controlled by varying the eccentric position of a controlling member thereof, then its output per one revolution may be thus controlled by varying this eccentric position to give a pump output per one revolution decreased when the engine is being started.

Abstract: A lock-up clutch control device for an automatic transmission having a torque converter with a lock-up clutch and a speed changing gear mechanism including a sub-transmission unit and a main transmission unit. The device has a lock-up operation device for producing a control signal when the sub-transmission unit is in the higher speed mode or when the main transmission unit selects 2nd or a higher speed gear. The control signal is delivered to a lock-up relay valve which operates effectively while it receives the control signal. Therefore, the torque converter can be locked up at 2nd or higher speeds of the automatic transmission which, because of various combinations of the states of the sub-transmission and main transmission units, outputs multiple speed.

Abstract: A support for an automatic transmission. The support has a tubular supporting portion having an inner peripheral surface supporting a transmission shaft and an outer peripheral surface supporting an inner cylindrical portion of a hydraulic servo drum of the transmission. The support has working oil passages formed therein and adapted for supplying and discharging a working oil to and from the hydraulic servo drum. The support has a support body including a first oil passage leading from an oil pressure controller for supplying and discharging working oil and communicating with the inner periphery of the tubular supporting portion, a second oil passage providing a communication between the outer periphery and the inner periphery of the tubular supporting portion and an inner oil groove providing a communication between inner peripheral openings of the first and second oil passages.