Abstract: A shift range device for an automatic transmission a shift lever shiftable to any one of a first neutral range, a reverse range, a second neutral range and one or more drive ranges which are arranged in the identified order. A neutral device includes a manual valve connected to the shift lever for establishing the neutral condition in such a manner that the manual valve inhibits the supply of oil pressure to any one of frictional engaging elements of the automatic transmission when the shift lever is transferred to the first neutral position or the second neutral position.

Abstract: An automatic transmission is controlled by detecting engine rmp following a transmission downshift and comparing the detected engine speed with a predetermined speed value. If the detected speed does not exceed the predetermined value, the solenoids controlling the down-shift are maintained energized. If the detected speed exceeds the predetermined speed value, the solenoids are de-energized to prevent overrunning of the engine.

Abstract: A hydraulic control circuit for an automatic transmission of at least 5 forward gear shift stages, which comprises:a first solenoid valve connected to each spool controlling hydraulic line pressure passage of a 1-2 shift valve and a 3-4 shift valve; anda second solenoid valve connected to a spool controlling hydraulic line pressure passage of a 4-5 shift valve;a third solenoid valve connected to a spool controlling hydraulic line pressure passage of at least 2-3 shift valvewherein each of said gear shift stages is established based on combination of ON-OFF operation of each of said solenoid valves.An inhibitor valve the valve is operative by any one of said first and second solenoid valves, and simultaneously establishing an inhibitor for solenoid valve disconnection and inhibitor for manual shift down operation. A manual range pressure at "3" or "2" is supplied to each friction member via at least two shift valves.

Abstract: A speed change control apparatus for an automatic transmission having a plurality of friction elements in which a gear stage is established by engaging one of the friction elements and disengaging one of the others. The speed change control apparatus includes control valves connected to respective ones of the friction elements, a duty solenoid valve connected to each oil line supplying a respective one of the control valves with control hydraulic pressure, and control means for engaging one friction element by outputting an engagement duty signal to one duty solenoid valve to control the control hydraulic pressure, and disengaging one of the other friction elements correspondingly by outputting disengagement duty signals to one of the other duty solenoid valves to control the control hydraulic pressure.

Abstract: A control circuit of a fluid coupling with a lock-up clutch includes a fluid coupling having a power chamber into which a working fluid is introduced for performing a transfer action between input and output elements via the fluid, a clutch member which suitably connects and disconnects the input and output elements, a working chamber formed separately of the power chamber, and a piston member displaced by a pressure difference between the working and power chambers to selectively engage and disengage the clutch member.

Abstract: A hydraulic control circuit for an automatic transmission is provided in which the automatic transmission has at least five forward gear shift stages. A plurality of solenoid valves are connected to hydraulic shift valves for controlling hydraulic line pressure utilized in the shifting between the various gear shift stages. Further, each of the gear shift stages is established dependent upon the operating condition of each of the solenoid valves. An inhibitor valve is provided which is operative by one of the solenoid valves and serves to provide an inhibiting function for solenoid valve disconnection and for manual downshift operation.

Abstract: If a vehicle is at rest after it has been detected that the shift position of the vehicle transmission has been shifted to neutral, hydraulic pressure is introduced to a brake in the transmission gear train that is for establishing the first speed state. The introduction of hydraulic pressure to the brake causes the brake to engage in advance of an actual shift to first speed. As a result, when the shift position is shifted out of the neutral range, the first speed state is quickly established, thereby shortening the neutral-to-drive shift time lag when the vehicle is at rest. If the vehicle is traveling after the shift to neutral has been detected, hydraulic pressure is exhausted from the brake to disengage the same, thereby preventing high-speed rotation of sun gears and clutch disk in the gear train due to transmission of rotation from the output side of the automatic transmission.

Abstract: A control circuit for a fluid coupling device with a high-gear clutch. The fluid coupling device includes a power chamber into which a working fluid is introduced for performing a transmission action, a clutch member arranged for connecting and disconnecting the input and output elements, a working chamber formed separately of the power chamber and a piston member forcibly displaced by a pressure differential between the working chamber and the power chamber for engaging or disengaging the clutch member. A fluid pressure source supplies working fluid to the interior of the power chamber and a high-gear clutch control valve supplies fluid to and discharges fluid from the working chamber for controlling the engagement and disengagement of the clutch.

Abstract: A control method of an automatic transmission for an automobile with exhaust brake provided, which includes a control signal given from an exhaust brake control arrangement, if a sensor indicates that the degree of throttle opening is zero and if a judging arrangement indicates that the downshift point is not yet passed over, downshift is performed by an automatic speed change, whereby the engine brake in addition to the exhaust brake is made effective to thereby secure a large braking force.

Abstract: The present invention provides an automatic transmission provided with an oil temperature increase prevention mode which automatically shifts gears on the basis of a gear-change pattern of that mode, and which is one of a plurality of gear-change patterns, in which downshift points are shifted toward the high-speed side from a standard gear-change pattern when the oil temperature signal rises above the level of a signal corresponding to a given temperature; and a control system for judging that oil temperature has increased to a given temperature on the basis of the oil temperature signal, and generating control signal so as to change the mode to the oil temperature increase prevention mode.

Abstract: An apparatus for controlling a transmission comprises a power transmission assembly for transmitting power from an engine, an input member connected to an output side of the power transmission assembly, a first power train connected to the input member and having at least two different speed-change ratios, a second power train communicating with the first power train and including a dog clutch for cutting off or changing over power, a brake assembly for locking the input member, and a clutch assembly for engaging and disengaging the input member with the first power train. A control system is provided for engaging the brake assembly in response to a signal indicative of changing-over of the second power train when the clutch assembly is in the disengaged state.

Abstract: A transmission control system for automatic transmission having a mechanism for detecting the engine condition, the vehicle speed and the vehicle load and a control mechanism for automatically calculating and setting an appropriate gear ratio of the transmission basing upon the detected values. The control mechanism is so designed that the judgment on whether or not the start at a high speed gear ratio is allowable can be made before the vehicle stops, and the setting of the gear ratio at the time of vehicle stop is made automatically to a high speed gear ratio or a low speed gear ratio according to the above judgment.

Abstract: A governor valve assembly for regulating hydraulic pressure by utilizing centrifugal force developed by the output shaft of a vehicle transmission when the output shaft is rotated has a first governor valve adapted for two-stage pressure regulation and a second governor valve for adapted for a single stage of pressure regulation disposed separately in a governor body supported on an output shaft. An output port of either one of the valves is communicated with a feed port of the other through a passageway in the governor body in order to obtain a three-stage hydraulic pressure characteristic.