Abstract: A hydraulic servo-mechanism for an automatic transmission, including a hydraulic servo for applying a band brake to engage a band to a drum. The hydraulic servo includes a rod which is selectively positionable to an apply position for applying the band brake, a standby position in which the rod is retracted by a predetermined extent in a release direction from the apply position, and a retracted position in which the rod is further retracted in the release direction from the standby position to release the band brake.

Abstract: A vehicular automatic transmission for establishing a plurality of forward gear stages, includes: a transmission case; an input shaft; a transmission mechanism connected to the input shaft and including a plurality of transmission elements; an output shaft connected to the transmission mechanism; first and second clutches at opposite ends of the transmission mechanism and drivably connecting the input shaft with at least one of the transmission elements; and first and second hydraulic servos for applying the first and second clutches responsive to feed of an oil pressure. The transmission case encloses the transmission mechanism, the clutches and the hydraulic servos, and includes axial end walls forming cylinders for the hydraulic servos.

Abstract: Smooth driving of a vehicle is achieved by eliminating busy shift by providing a small gear ratio step between the two highest gear ranges while maintaining structural compactness of the transmission. In the second highest gear range or state, a first pinion P1 has a diameter smaller than that of a second pinion P2, both pinions P1 and P2 being coupled integrally and at least partially determining the second highest gear ratio. The gear ratio .lambda..sub.2 in the second highest gear range is described as 1+(Z.sub.S2 /Z.sub.R1).times.(Z.sub.P1 /Z.sub.P2). Since (Z.sub.P1 /Z.sub.P2) is always equal to 1.0 or less, the gear ratio can be made smaller without enlarging the diameter of the ring gear R1 significantly to decrease the gear ratio step to the highest gear range.

Abstract: To optimize the application hydraulic pressure of the friction application elements in the transmission mechanism, and to reduce the unnecessary load on each member, the transmission mechanism of an automatic transmission is provided with a plurality of friction application elements which are applied simultaneously in order to achieve the designated gear stage, and hydraulic servos which operate the friction application elements independently. The control apparatus has an information detecting means, an input torque calculating means which calculates the input torque of the transmission mechanism on the basis of this information, an application hydraulic pressure calculating means which calculates the necessary application hydraulic pressure required to maintain the application of each individual friction application element on the basis of the input torque, and a supply means which supplies the necessary application hydraulic pressure to the hydraulic servos of the friction application elements.

Abstract: Uncomfortable travel of a vehicle due to engine brake actions during the travel of the vehicle in traffic is prevented without using an one-way clutch within a transmission mechanism. An automatic transmission is composed of rotational elements that are braked at the time of establishing low stages, a brake that brakes the rotational elements, and control systems which control the oil pressure of the hydraulic servo in the brake. A band brake that creates differences in application forces, using self-energizing and deenergizing actions, serves as the brake, which is set to have an area in which the oil pressure during the drive is lower than the oil pressure during the non-drive, by setting the self-energizing direction as a direction of rotation of the rotational element during the drive and the deenergizing direction as an opposite direction of rotation of the rotational element during the non-drive.

Abstract: A compact structure for a speed change mechanism within a transmission is shown. An automatic transmission includes an input shaft supported at its opposite ends, an input member operatively connected to a first end of the input shaft, an output member mounted on a second end of the input shaft, and a speed change mechanism disposed between the input member and the output member, and including planetary gear trains supported on the input shaft. The portion of the input shaft supporting the planetary gear trains need not transmit torque, thus allowing the use of a reduced diameter input shaft.

Abstract: In a torque converter, in order to reduce the cost, simplify the manufacturing process and ensure the centering precision of of the stator relative to the outer race of a one-way clutch, the stator and the outer race of the one-way clutch have first engaging surface portions preventing relative rotation therebetween and second engaging surface portions providing concentricity therebetween. The first and second surface portions are axially offset from each other.

Abstract: A control system for an automatic transmission includes: a clutch adapted to be applied when a forward running range is selected, to transmit the rotation of an engine to the transmission mechanism of a speed change unit and a hydraulic servo for applying/releasing the clutch. A control unit controls oil pressure fed to the hydraulic servo and includes: an application starting pressure detector for detecting application starting pressure at the instant when the application of the clutch is started; an initial application pressure setter for setting an initial application pressure on the basis of the detected application starting pressure; and an oil pressure regulator for adjusting the oil pressure fed to the hydraulic servo, when a change is made to a forward running range, and then gradually raising that oil pressure.

Abstract: In order to improve transmission efficiency of an automatic transmission, an engagement brake which does not cause drag is used and the surety of its engagement and release, and quick switching between forward maneuver and backward maneuver, is enabled. The automatic transmission comprises a transmission mechanism to achieve forward maneuver and backward maneuver. A backward motion brake which stops the rotation element to achieve backward maneuver is the engagement brake and an input clutch to transfer power by meshing with the rotation element during both forward maneuver and backward maneuver is a friction clutch. The control apparatus executes the control operation to prepare for speedy re-meshing by holding a supply pressure for the clutch hydraulic servo at a sufficient oil pressure to place the pressure in the stand-by condition at the piston stroke position immediately before the start of clutch engagement during the engagement or releasing of engagement of the engagement brake at the time of D.

Abstract: During transmission shifts, a band brake is used in either a self-loosening direction in which an engaging force thereof is not sensitive to variations in hydraulic pressure or a self-tightening direction in which the engaging force is sensitive to variations in hydraulic pressure. In the self-loosening direction, a second regulated hydraulic pressure generated by a second pressure regulating valve (B-4 control valve) in accordance with a control hydraulic pressure generated by a second (throttle-pressure-control) linear solenoid valve in a margin control region thereof is supplied to a hydraulic servo of the fourth brake (band brake). In this clutch-to-clutch shift, a first regulated hydraulic pressure generated by a first pressure regulating valve (a shift-pressure control valve) in accordance with a control hydraulic pressure generated by a first (pressure-regulation) linear solenoid valve is supplied to a hydraulic servo of a third (UD direct) clutch.

Abstract: A control system for an automatic transmission operates a clutch for disengaging a transmission mechanism when a vehicle is stopped and idling with the brake pedal depressed while the gear shift is in a forward gear. The clutch is maintained at a drag state (friction elements disengaged but oil causing some torque transmission) bordering a slip state (friction elements engaged) When a neutral control is started, the clutch is released until the retraction of the piston of the hydraulic servo is started. When the rate of change in a rotational difference does not exceeds a reference rate of change even after a set time has elapsed, booster means of specific release state holding means decides that the clutch is in a drag region, and raises an oil pressure to be fed to the hydraulic servo, by a set pressure.

Abstract: A control system for use in an automatic transmission having a transmission mechanism for establishing a plurality of forward stages, a neutral state and a reverse stage. The transmission mechanism includes a predetermined rotary element to be retained for establishing the reverse stage; a reverse brake for retaining the rotary element; and a frictional engagement element capable of stopping the rotation of the rotary element. The reverse brake is a meshing type brake which meshes with and retains the rotary element. The control system has an engagement mechanism for applying the frictional engagement element. When the reverse stage is selected, the frictional engagement element is applied at least until the meshing engagement of the reverse brake is established, to stop the predetermined rotary element.

Abstract: A control system for an automatic transmission operates a clutch in a speed change unit to disconnect a transmission mechanism from a fluid transmission unit during a neutral operating state while the vehicle in a forward gear is held stopped by braking with the throttle fully closed. Reengagement of the clutch such as by depression of accelerator pedal (throttle open), release of the brake pedal, etc., is produced by a gradual increase in oil pressure to the servo operating the clutch to prevent clutch application shock. Wear on the clutch is reduced by abrupt increase of the oil pressure in response to satisfaction of a clutch engagement completion condition based upon input RPM, output RPM and the gear ratio of the target gear.

Abstract: A hydraulic pressure control apparatus for an automatic transmission including a microprocessor-based control unit for controlling hydraulic pressure supplied to hydraulic servos of friction engagement elements. The control apparatus calculates a target hydraulic pressure P.sub.TA for a condition at the start of the inertia phase in accordance with the input torque, and a gradient based on the target hydraulic pressure and a predetermined time t.sub.TA. A first up-sweep of hydraulic pressure is performed by the apparatus with the gradient. A relatively gradual gradient .delta.P.sub.TA is set based on a target rotation change rate for the input rotational speed to provide a predetermined change amount when the hydraulic pressure becomes the target hydraulic pressure P.sub.TA. The control apparatus performs a second up-sweep with the gradient .delta.P.sub.TA. When the rotational speed change .DELTA.N of the input rotation becomes a rotation change start-determining rotational speed dN.sub.

Abstract: To achieve a predetermined speed by engaging or releasing friction engagement elements of an auxiliary shift mechanism, a fluid pressure changeover valve is switched to a position for communication between a regulated pressure input port and an output port, so that regulated fluid pressure from a pressure regulating valve is supplied through second shift mechanism-side shift valves to the friction engagement elements of the auxiliary shift mechanism to be engaged or released. This position switch of the changeover valve also connects a line pressure input port to an output port whereby line pressure is supplied to the main shift mechanism-side shift valves to maintain the main shift mechanism in a predetermined speed state.

Abstract: A control system for an automatic transmission includes a clutch adapted to be applied when a forward running range is selected, for transmitting the rotation of an engine to a speed change unit. A hydraulic servo applies the clutch responsive to feed of an oil pressure and a control unit controls the oil pressure fed to the hydraulic servo. The control unit brings the clutch into a substantially released state by lowering the oil pressure of the hydraulic servo if the stop state of a vehicle is detected by a stop state detector and applies the clutch if the stop state of the vehicle is not detected with the clutch released. The oil pressure fed to the hydraulic servo is raised according to a second mode when the accelerator pedal is depressed, in preference to a first mode in which a brake pedal is released, if the accelerator pedal is depressed when the stop state of the vehicle is not detected because the accelerator pedal is released so that the engagement of the clutch has not started.

Abstract: An automatic transmission has a reduced axial dimension and includes a mission case portion providing a mounting surface for a valve body. Forces generated by a hydraulic servo in operation of a brake are confined to the inside of a rear cover joined to the mission case. An extension protrudes from the rear cover and extends into the interior of the mission case with a multi-plate brake splined thereto. The force generated in operation of the brake is received by the cylinder as a reaction force. However, since the hydraulic servo cylinder and the extension are both integral with the rear case, the reaction force is confined to the interior of the rear cover without acting on the mission case.

Abstract: A hydraulic power transmission unit includes a casing connected to an engine, a pump member fixed to the interior of the casing and a turbine mounted within the casing and connected to an output shaft, whereby the output torque of the engine is transmitted to the output shaft through fluid in the casing. A damper mechanism includes damper springs mounted directly on the inner face of the casing at its outer circumference. A damper disc serves to transmit the power of the engine to the output shaft through the damper springs. A lock-up clutch mechanism is also housed within the casing and includes a frictional engagement element arranged between the damper disc and the output shaft. The lock-up clutch mechanism is operated, i.e. frictional engagement element selectively applied and released, by a clutch piston slidably mounted within a cylinder defined by the damper disc.

Abstract: The invention provides a control apparatus for an automatic transmission for carrying out neutral control and hill-hold control in a range that causes no slip of a hill-hold brake.

Abstract: A control system for an automatic transmission includes: an input clutch applied, responsive to selection of a forward running range, to transmit the rotation of an engine to a transmission mechanism; a hydraulic servo for selectively applying/releasing the input clutch; a stop state detector for detecting a stop state of a vehicle in terms of the selection of the forward running range, lack of vehicle speed, the release of an accelerator pedal and the depression of a brake pedal; starting operation detector for detecting an operation to start the vehicle in motion; application state detector for detecting the application state of the input clutch; and a controller for controlling oil pressure fed to the hydraulic servo on the basis of signals coming from the various detectors.