Abstract: A hydraulic control apparatus for an automatic transmission of a motor vehicle, the transmission including a lock-up clutch, the apparatus including a lock-up clutch switching valve device which is operable for selectively placing the lock-up clutch in a fully released, a partially engaged, and a fully engaged state thereof; a hydraulic pressure producing device which produces a hydraulic pressure; an abnormality detecting device which detects an abnormality of at least one of the lock-up clutch and the lock-up clutch switching valve device; and a control device which, when the abnormality detecting device detects the abnormality, operates the hydraulic pressure producing device for one of (a) applying the hydraulic pressure, and (b) inhibiting the hydraulic pressure from being applied, to at least one of the lock-up clutch and the lock-up clutch switching valve device for forcibly placing the lock-up clutch in one of the fully released and fully engaged states thereof.

Abstract: A control system for an automatic transmission, comprising a gear transmission unit for establishing a predetermined gear stage by applying a plurality of frictional engagement elements selectively. The gear transmission unit includes a main transmission portion capable of establishing at least a reverse gear stage, and an auxiliary transmission portion capable of switching a high gear stage and a low gear stage. The auxiliary transmission portion is set to the high stage at the shifting time to the reverse stage. The reverse stage is established by controlling the application of predetermined frictional engagement elements of the main transmission portion when a reverse stage shifting command is generated. A torque-down of an engine is executed at the time of controlling the engagement of the frictional engagement elements for the reverse stage.

Abstract: A hydraulic control for an automatic transmission is composed of a gear shift mechanism having first and second frictional engagement elements, a hydraulic control unit for the engagement elements, and an electronic control unit for the hydraulic control unit. The first element is engaged to achieve a first speed stage and the second element is engaged to achieve a second speed stage faster than and closest to the first speed stage. The hydraulic control unit has a first directional control valve for switching the feeding and discharge of hydraulic pressure between the first and second engagement elements, responsive to a first solenoid signal from the electronic control unit. A second directional control valve is adapted to be switched by a second solenoid signal from the electronic control unit to achieve a third speed stage yet faster than the second speed stage. The first engagement element has a discharge line connected to a drain line via the second directional control valve.

Abstract: Thrust force generated by a hydraulic actuator is absorbed in a attachment device for a four speed automatic transmission mechanism. When hydraulic pressure is applied to the hydraulic actuator to engage a third and a fourth clutches, pressing force from a piston works on a strut member situated between the third and fourth clutches as a compression force, while a force working on a drum member as a tension force, so that these forces are counterbalanced and absorbed in the attachment device. Consequently, one directional move of the attachment device is supported by a little force such as contacting a snap ring and a thrust washer to a clutch drum, on the other hand, another move of the attachment device is supported by a little force such as connecting the drum member and a big ring gear by a snap ring.

Abstract: A centrifugal hydraulic pressure cancel chamber is arranged at the back of a second piston member of a second hydraulic actuator for the second clutch. A first piston member of a first hydraulic actuator for a first clutch is situated behind the second piston. A centrifugal hydraulic pressure cancel plate is set at an inner periphery on a rotating member to prohibit axial movement and set at an outside periphery in a inside of the piston member oil-tightly. The inside surface of the second piston member and the cancel plate compose the centrifugal hydraulic pressure cancel chamber. A spring is placed between the second piston member and the cancel plate, and the centrifugal hydraulic cancel chamber and the spring work correspondingly to the first and the second piston members.

Abstract: A hydraulic control device which has a check valve controlling hydraulic pressure to a hydraulic actuator. Hydraulic pressure is selectively supplied to one of plural oil passages having different capacity orifices by a switching valve which switches high speed rotation mode and low speed rotation mode. A hydraulic power source and plural oil passages having different capacity orifices are connected to the switching valve which is controlled by hydraulic pressure varying according to vehicle speed. When rotation of the input shaft is low, the switching valve is connected to the oil passage having small capacity orifice, then hydraulic pressure is supplied to the hydraulic actuator through the orifice of small capacity. At this stage, as centrifugal force working on the ball in the check valve is low, the check valve is closed by even small amount of oil supply through the small capacity orifice, and raises hydraulic pressure in the actuator, so the clutch is engaged smoothly.

Abstract: A rotation detecting sensor is situated on the inside of a sleeve, so that the sensor detects a detected member, such as an input shaft and the like for an automatic transmission, from the inside of the sleeve. A hub projected toward inside a case is constituted, a sleeve enclosing the hub is fixed on the rotating shaft, the rotation detecting sensor is installed on the hub so that the sensor faces a detected member constituted on the inner surface of the sleeve. By this, the rotating shaft such as the input shaft and the like rotates with being supported by the hub of the case, and the sleeve fixed on the rotating shaft rotates together. The detected member is detected by the rotation detecting sensor placed at the hub.

Abstract: An intake adapter is provided on an oil intake opening formed in a transaxle casing. A tightly sealed space in communication with an oil pump is provided in the lower part of the transaxle housing, formed in such a manner that it can be opened by the removal of a cover member which is secured to the transaxle casing in a freely mountable and removable manner. An oil strainer is housed in the tightly sealed space and an intake adapter is provided in communication with the tightly space and an oil sump. As a result the oil in the oil sump is taken into the intake opening of the oil strainer from the adapter, and foreign matter such as iron particles and the like is removed in a filter element and the filtered oil is supplied to an oil pump.