Abstract: Disclosed is a hydraulic control system for an automatic transmission that controls a powertrain, which includes a first friction element for use as an engine brake for discontinuing operation of a one-way clutch in the transmission and a second friction element operating only when the first friction element is disengaged. The hydraulic control system comprises a manual valve including a forward range port for exhausting hydraulic pressure when driving in a forward range, and an L range port for exhausting hydraulic pressure for low speed control; and a switch valve controlled by engine brake signal pressure, solenoid pressure, and forward range pressure supplied from the forward range port, the switch valve selectively supplying control pressure to the first friction element and the second friction element.

Abstract: A hydraulic pressure control device for an automatic transmission in which a single control valve selectively applies control pressure to friction elements includes a control valve and a shift valve. The control valve has a control port from which control pressure is outputted after being adjusted by a linear solenoid valve, and first and second feedback ports to which the control pressure is fed back. The shift valve is positionable in a first position when the control pressure is applied to the first friction element and a second position when the control pressure is applied to the second friction element, and is adapted to lower the control pressure outputted by the control valve in the second position of the shift valve by controlling communication of the control port with the feedback ports. In addition, an ON-OFF solenoid valve switches the position of the shift valve.

Abstract: A shift control system of an automatic transmission executes an interchange shift by interchanging engagement conditions of first and second friction elements of the automatic transmission. The first and second friction elements are engaged and disengaged according to oil pressures supplied thereto. A controller of the shift control system is arranged to decrease the second oil pressure of the second friction element by a second predetermined gradient and to increase the first oil pressure of the first friction element by a first predetermined gradient after the loss stroke of the first friction element is terminated, and to determine the first gradient such that a difference between a command pressure and an actual pressure of the first friction element is kept substantially constant.

Abstract: A system for controlling an automatic transmission of a vehicle, in which a pressure supply time to complete removal of the clutch-stroke play is determined based on the input shaft rotational speed. And a residual oil amount in the clutch is estimated and the time is corrected by the residual oil amount. The preparatory pressure to be supplied within the time is also determined based on the input shaft rotational speed and the ATF temperature. With this, it becomes possible to effect the clutch-stroke play removal within a less variant time and with a good response, thereby decreasing the shift shock effectively so as to improve the feeling of the vehicle occupant.

Abstract: The present invention relates to a hydraulic control system, in which a powertrain of a 5-speed automatic transmission is controlled using five clutches and three brakes such that fuel consumption is reduced and engine torque is more efficiently utilized. The hydraulic control system includes four pressure control valves, three switching valves, and three fail-safe valves that are controlled by solenoid valves.

Abstract: The power transmission has a fly-by-wire electro-hydraulic control mechanism that controls the engagement and disengagement of the range clutches in both forward and reverse operation. In forward operation, the control mechanism permits continued vehicle operation in the third forward range should electrical discontinuance occur during the first through fourth forward ranges, and in the fifth forward range should electrical discontinuance occur in the fifth or sixth forward range. Also, the control mechanism includes two logic valves and a forward on/off solenoid valve that permits the logic valves to control three torque-transmitting mechanisms with the use of two trim solenoid valves.

Abstract: An automatic transmission for a vehicle comprises a torque converter TC equipped with a lock-up clutch 4. This automatic transmission further comprises FIRST˜FOURTH speed clutches 31˜34 for a shift control executing a shift from off-going speed ratio to an on-coming speed ratio by controlling the release of the hydraulic pressure from the off-going clutch and by controlling the supply of the hydraulic pressure to the on-coming clutch. A control system comprises first and second off-going pressure releasing valves 70 and 80, which release the hydraulic pressure from the off-going clutch during the shift, a lock-up control valve 40 and a lock-up timing valve 50, which control the engagement of the lock-up mechanism, and a linear solenoid valve 60, which supplies a control pressure to these valves and controls the operation of these valves.

Abstract: An electro-hydraulic control for a six speed power transmission has three shift control valves that are each actuated by a spring and a solenoid valve. The shift valves are positioned in either a spring set or a pressure set position to establish flow paths to five torque transmitting mechanisms (friction devices) that are engaged according to a predetermined schedule to establish six forward speed ratios and one reverse ratio. A pair of high ratio control valves and a pair of low ratio control valves operate to control the actuation pressures for the friction devices. The actuation pressures are distributed through a switching valve. The high ratio control valves control the on coming friction device with an increasing pressure schedule while the low ratio control valves control the off going friction device with a decreasing pressure schedule.

Abstract: To reliably establish a shift in a hydraulic pressure control device for an automatic transmission in which a control valve applies a control pressure, by way of a shift valve, to a plurality of friction engaging elements, the hydraulic pressure control device is designed to establish an intermediate shift pattern. The hydraulic pressure control device includes an electronic control unit that establishes shift pattern 3 to produce the second and third gear stages and shift pattern 5 to produce the third, fourth and fifth gear stages in which ON-OFF solenoid valves under energization are combined to produce both the second and third gear stages.

Abstract: An electro-hydraulic control for a six speed power transmission has three shift control valves that are each actuated by a spring and a solenoid valve. The shift valves are positioned in either a spring set or a pressure set position to establish flow paths to five torque transmitting mechanisms (friction devices) that are engaged according to a predetermined schedule to establish six forward speed ratios and one reverse ratio. A pair of high ratio control valves and a pair of low ratio control valves operate to control the actuation pressures for the friction devices. The actuation pressures are distributed through a switching valve. The high ratio control valves control the on coming friction device with an increasing pressure schedule while the low ratio control valves control the off going friction device with a decreasing pressure schedule.

Abstract: In an automatic transmission for conducting a gear change by replacing friction engagement elements, a transmission torque capacity of an engage side friction engagement element at a torque phase is corrected based upon a change amount per unit time of a turbine rotation speed at the torque phase or a torque phase time.

Abstract: An automatic transmission, which has automatic shift ranges and manual setting ranges having a first speed gear position at which an engine brake is operable, is constructed in such a manner that a first friction element engaged at the first speed gear position and at a backward driving gear position is connected to a pressure regulating valve controlled by a timing solenoid valve. If a gear position is automatically shifted from a gear position at which the first friction element is unengaged to a gear position at which the first friction element is engaged, the timing solenoid valve is kept on for a predetermined time to delay the engagement of the first friction element to thereby prevent the shock from the shift.

Abstract: An improved control for an automatic transmission closed-throttle downshift, wherein closed-throttle engine torque is used to raise the transmission input speed to the synchronous speed of the target speed ratio, and wherein the on-coming clutch is controlled in a manner to complete the shift with minimum driveline torque disturbance in spite of clutch control variability. The invention includes a primary on-coming clutch control for completing the downshift when the input speed reaches the synchronous speed, and a contingent on-coming clutch control that is initiated if shift completion is not achieved by the primary control, the contingent control being effective to re-establish input speed synchronization and thereupon engage the on-coming clutch to complete the shift.

Abstract: During a shifting operation that a first engaging element is changed from an engaged state to a disengaged state, a fail-safe valve is used to forcibly drain a first engaging-element pressure from the first engaging element by using a second engaging-element pressure applied to a second engaging element brought into an engaging state from a releasing state. The fail-safe valve includes a spool and uses the second engaging-element pressure acting on the spool in one axial direction and an opposing pressure acting on the spool in the opposing direction as operating signal pressures. The fail-safe valve is switchable to a drain position, when the second engaging-element pressure is regulated toward a specified fail-safe valve operating point pressure higher than a maximum pressure value of the second engaging-element pressure regulated during the shifting operation and lower than a maximum possible engaging-element pressure.

Abstract: A shift control method for an automatic transmission which includes converting to a lean-burn mode from a normal mode if throttle voltage is less than a first predetermined value; determining if tip-in has occurred in the lean-burn mode using accelerator pedal signals; increasing the throttle valve opening if it is determined that the throttle voltage has increased by a second predetermined value such that engine rpm is increased; determining if the difference between engine rpm and turbine rpm is greater than a predetermined number of rpm; and converting from the lean-burn mode to the normal mode if the engine rpm are greater than the turbine rpm by the predetermined number of rpm.

Abstract: A hydraulic control device for an automatic transmission that can ensure power transmission when a failure occurs to the solenoid valve of the hydraulic control device, the hydraulic control device having a plurality of hydraulic servos for engaging and disengaging a plurality of friction engagement elements in accordance with the supply and discharge of a hydraulic pressure so as to prevent interlock from occurring to the transmission, a solenoid valve for generating a predetermined hydraulic pressure and supplying the predetermined hydraulic pressure to a hydraulic servo selected in correspondence with a target gear ratio and fail-safe means for supplying fail-safe hydraulic pressure to at least two hydraulic servos selected to attain an arbitrary gear ratio when a failure occurs to the solenoid valve and power transmission thereby becomes impossible.

Abstract: An automatic control strategy for use with a multiple-ratio transmission in an automotive vehicle driveline in which the crankshaft of an internal combustion engine is connected directly to torque input elements of multiple-ratio gearing without an intervening hydrokinetic torque converter. The strategy is adapted especially for use with a wet auto clutch to provide forward or reverse drive engagement during vehicle launch and during transient damping of driveline disturbances. The strategy makes it possible to control the clutches to achieve maximum vehicle acceleration by controlling the engine speed so that it operates at maximum torque throughout the useful engine speed range for any given engine throttle position. The entry and exit conditions for each drive mode are determined by the strategy so that optimum drive-away performance and optimum shift control, as well as soft clutch engagement and full clutch engagement, can be achieved.

Abstract: In an automatic transmission for conducting a gear change by replacing friction engagement elements, a transmission torque capacity of an engage side friction engagement element at a torque phase is corrected based upon a change amount per unit time of a turbine rotation speed at the torque phase or a torque phase time.

Abstract: In a constitution that a transmission torque capacities of friction engagement elements are determined based on an input shaft torque of a speed change mechanism and a torque sharing ratio, a change velocity of the torque sharing ratio of when the transmission torque capacity of a release side friction engagement element is changed from a value greater than a critical transmission torque capacity to a value smaller than the critical transmission torque capacity, is abruptly altered when the input shaft torque is equal to or less than a predetermined value.

Abstract: A transmission control system consists essentially of two actuating cylinders, a pressure supply system, a controllable valve system for connecting the actuating cylinders to the pressure supply system, and an electrical control system for actuating the controllable valve system. In order to create a compact control system unit, the controllable valve system, at least part of the pressure supply system, and the electrical control system are all combined into a single integrated component. Alternatively, the actuating cylinders may also be included within the single component.

Abstract: A hydraulic control apparatus of automatic transmission comprising a hydraulic pressure source, hydraulic paths, hydraulic servos for operating friction elements which are coupled with the hydraulic source and the hydraulic paths, a control device arranged on the hydraulic paths for operating engagement release through supply/removal of hydraulic pressure to the hydraulic servos and valves which are arranged on the hydraulic path for cutting off hydraulic pressure from the hydraulic pressure source to the hydraulic servo with hydraulic pressure in the downstream side of the control means as signal pressure.

Abstract: A control for a multi-speed transmission has a multiple gain trim valve that controls the engagement pressure rise in a selectively engageable torque transmitting mechanism. The trim valve has a valve spool and a plug valve longitudinally aligned in a valve bore such that four separate areas are present. One of the areas has the engagement pressure of the torque transmitting mechanism imposed thereon. Another of the areas has a control pressure imposed thereon and the remaining two areas are subjected to the trim pressure. The gain rate between the trim pressure and the engagement pressure determines the rapidity with which the torque transmitting mechanism is engaged. The control pressure reduces the effect of the trim pressure to provide a low gain rate until the product of the trim pressure and one of the areas is equal to or greater than the product of the control pressure and the area on which it operates.

Abstract: A powertrain has a multi-speed transmission with an electro-hydraulic control system for establishing the operating conditions of the transmission. The control system has a plurality of shift or relay valves that are each alternatively positioned by a spring or a solenoid controlled pressure bias. One of the relay valves, which controls two friction devices, has a latching mechanism which will retain the valve in the pressure set condition until the pressure in one of the friction devices is decreased below a predetermined pressure. The latch mechanism will also serve to retain the transmission in a low forward ratio if an electrical discontinuance should occur when the transmission is conditioned for the low forward ratio. The control will also permit retention in the highest forward ratio if electrical discontinuance occurs during operation in this ratio. Following an engine shutdown and restart, the transmission can be selectively operated in a reverse ratio, a neutral condition or the third forward ratio.

Abstract: A shift control method for an automatic transmission not equipped to undergo skip shifting. Various skip shifting patterns are realized by detecting changes in turbine RPM, and delaying shifting if it is determined that turbine RPM are irregular, thereby achieving a normal shift pattern.

Abstract: Measurement is made of a time of lapse from the time at which the hydraulic pressure of the hydraulic engaging element on engaging side to be engaged at the time of speed changing has increased to a predetermined pressure. Even if an input and output speed ratio of the transmission does not fall within a predetermined range, i.e., a range between YG(N+1)L and YG(N+1)H, which serves as a basis for judging whether the speed changing has been completed or not, a processing of speed change completion is performed when the above-described value TMSTB-TM has reached a predetermined value YTMUP4, to boost the ON pressure to the line pressure.

Abstract: Disclosed is a shift control method for automatic transmissions.

Abstract: In select-shock control apparatus and method for a vehicular automatic transmission, the automatic transmission having a friction element to be released when a range selection from a vehicular running range to a neutral range occurs, a determination is made whether the range selection from the vehicular running range to the neutral range occurs; a transient hydraulic pressure control is performed such that a hydraulic pressure drawn out from the friction element is reduced up to a pressure level such as not to generate a shock which would occur in the vehicle when the range selection occurs, the level of the drawn out hydraulic pressure is maintained for a time duration at an end of which no vehicular running torque is left in the friction element, and, thereafter, an engagement torque developed on the friction element is drawn out at a dash when determining that the range selection from the vehicular running range to the neutral range occurs.

Abstract: A system for controlling gear (gear ratio) shifting in an automatic transmission mounted on a vehicle, including a shift control means for generating a shift command to upshift from one gear (gear ratio) currently established to a next gear (gear ratio) by determining a command to the solenoid valves to discharge the pressurized oil from the frictional engaging elements that establish the current gear (gear ratio) so as to slip-control the frictional engaging elements, and to charge the pressurized oil to the frictional engaging elements that establish the next gear (gear ratio) to be shifted to.

Abstract: Disclosed is a hydraulic control system used in an automatic transmission for a vehicle which includes a plurality of friction elements associated with respective transmission speeds, a hydraulic pressure source, a hydraulic pressure regulating controller for controlling hydraulic pressure from the hydraulic pressure source to constant line pressure, a damper clutch controller for actuating a damper clutch of the torque converter by supplying hydraulic pressure fed from the pressure regulating controller to the torque converter, shift controller for selecting a shift mode by converting hydraulic pressure from the pressure regulating controller into drive pressure corresponding to each speed stage, a hydraulic pressure controller for controlling the drive pressure from the shift controller, and a hydraulic pressure distributor for suitably distributing hydraulic pressure from the hydraulic pressure controller to each friction element for each speed, wherein the hydraulic pressure distributor includes a shift t

Abstract: A control system for an automatic transmission, in which a first frictional engagement element and a second frictional engagement element are released according to a shift from a running range to a non-running range. The shift from the running range to the non-running range is detected, and the reduction in the oil pressure of the second frictional engagement element is controlled on the basis of the reduction in the oil pressure of the first frictional engagement element when the shift from the running range to the non-running range is detected.

Abstract: In an automatic transmission of an automotive vehicle equipped with a change-speed gear train capable of selectively establishing first-speed to fourth-speed drive power trains, there are provided first and second solenoid valves each in the form of a normally open valve arranged to be supplied with fluid under pressure at its output fluid passage in a deactivated condition, third and fourth solenoid valves each in the form of a normally closed valve arranged to permit fluid under pressure discharged from its output fluid passage in a deactivated condition, a first spool valve for fail-safe arranged to disengage a first hydraulic brake of the change-speed gear train when all the solenoid valves are supplied with the fluid under pressure at their output fluid passages or when the fourth solenoid valve and either one of the first, second and third solenoid valves are supplied with the fluid under pressure at their output fluid passages, and a second spool valve for fail-safe arranged to disengage a second hydra

Abstract: The present invention provides a hydraulic control system for automatic transmissions, which includes line pressure control mechanism for regulating hydraulic pressure generated in an oil pump to a line pressure level, damper clutch control mechanism for receiving the line pressure to control a damper clutch, shift control mechanism for receiving the line pressure and supplying the same according to each shift mode, hydraulic pressure distributing meachanism for receiving hydraulic pressure from the shift control mechanism and supplying the same to a plurality of friction elements, and hydraulic pressure control mechanism for regulating the line pressure and supplying the same to the hydraulic pressure distributing mechanism to correspond to each shift mode wherein abrupt pressure exhaust preventing mechanism is provided which slows exhaust of hydraulic pressure when shifting from drive D or reverse R ranges to a neutral N range.

Abstract: The hydraulic control system for an automatic transmission having a plurality of friction elements includes a pressure regulator which regulates hydraulic pressure produced by an oil pump, a plurality of valves selectively supplying hydraulic pressure to the plurality of friction elements, and a pressure controller controlling and selectively supplying hydraulic pressure to a plurality of pressure control lines operationally connected to the plurality of valves and at least one of the plurality of valves. The plurality of valves include a first valve operationally controlled by hydraulic pressure in a first one of the pressure control lines to pass the hydraulic pressure output by the pressure controller to at least one of the plurality of friction elements in each operational range except a first speed stage of a drive range.

Abstract: A hydraulic control device for automatic transmissions is disclosed. The control device of this invention includes a valve means, of which the valve spool is selectively actuated by a drive pressure, the spring force of a valve spring or a control pressure from the PCV, with the control pressure being used in event of an R-N-D shifting operation. The hydraulic control device thus slowly releases the front clutch pressure during an N-D shifting operation and quickly releases the front clutch pressure during an R-N-D shifting operation, thus smoothly performing the R-N-D shifting operation without generating any shifting shock.

Abstract: An apparatus for controlling an automatic transmission of a motor vehicle which is shifted to a non-drive position with a releasing action of a hydraulically operated frictional coupling clutch upon operation of a manually operated member from a drive position to a non-drive position, the apparatus including a non-drive shift detecting device for detecting a non-drive shifting operation of the manually operated member from the drive position to the non-drive position, a rapid pressure reduction device operated upon detection of the non-drive shifting operation for rapidly reducing a pressure of the hydraulically operated frictional coupling device to a predetermined pressure level, and a continuous pressure reduction device for continuously reducing the pressure of the frictional coupling device from the predetermined pressure level at a predetermined reduction rate.

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: Methods and systems for improving the operation of a transmission for an automotive vehicle, and in particular the transmission as installed by the original automobile manufacturer, modify the original hydraulic fluid circuits of the automotive transmission installed by the automobile manufacturer to enable the "factory installed" transmission to hold first gear in the first gear selector position through any rotational speed of the engine. Further modifications to the hydraulic circuitry enable the operator of the vehicle to select fourth gear manually at relatively high vehicle speeds at wide open throttle conditions. Additional modifications to the hydraulic circuitry increase the third clutch capacity at high throttle during a "2-3" shift, and result in firm and more correctly timed shifts.

Abstract: A shift control system for an automatic transmission to execute a clutch-to-clutch shift by applying a first frictional engagement device and releasing a second frictional engagement device and another shift by applying the first frictional engagement device to cause a rotational change in a predetermined rotary member. At a shift other than the clutch-to-clutch shift, there is detected a stroke time from the feed of an oil pressure to the first frictional engagement device to the start of the engagement. At the clutch-to-clutch shift, the timing for releasing the second frictional engagement device is controlled on the basis of the stroke time.

Abstract: A control system for use in an automatic transmission which includes a gear shift mechanism having first and second frictional engagement elements for establishing: a first gear stage with the first frictional engagement element being applied and the second frictional engagement element being released; and a second gear stage with the first frictional engagement element being released and the second frictional engagement element being applied. The control system, in turn, includes: a first oil passage for feeding an oil pressure to the first frictional engagement element; a second oil passage for feeding an oil pressure to the second frictional engagement element; and a first valve arranged in the first oil passage for regulating the oil pressure of the first oil passage. At the time of a shift from the first gear stage to the second gear stage, the oil pressure of the first oil passage is regulated by the first valve responsive to the oil pressure of the second oil passage.

Abstract: An automatic transmission includes the transmission control device which sets a control time upon changeover from the second gear condition to the third gear condition during which the brake device is maintained in the engaged condition until changing to the disengaged condition. The transmission control device also adds a compensating time to the control time upon changeover from the second gear condition to the third gear condition in certain circumstances such as when changeover from the second gear condition to the third gear condition follows operation under the first gear condition, and when change over from the second gear condition to the third gear condition follows vehicle operation under the second gear condition for a period exceeding a predetermined time (e.g., 10 seconds).

Abstract: A pressure regulating portion having a pressure regulating valve regulates hydraulic pressure fed from a hydraulic pump and a shift control part having a manual valve and a shift control valve feeds hydraulic pressure fed from the pressure regulating portion in response to each shift mode. A pressure control portion controls hydraulic pressure to be proper to each shift mode. The pressure control part includes first and second pressure control solenoid valves, and first and second pressure control valves and an N-R control valve. A pressure dispensing part dispenses hydraulic pressure fed from the shift control part and the pressure control part to first, second, third, fourth and fifth friction members. A switch valve feeds selectively hydraulic pressure fed from the second pressure control valve to the first and fourth friction members. A pressure damping member is disposed on a line connected to the third friction member which is applied in third and fourth speeds of a drive "D" range.

Abstract: An automatic transmission for an automotive vehicle comprises electromagnetic valves 5A-5C activated or deactivated in accordance with a given shift schedule determined based on traveling conditions of the automotive vehicle, a plurality of planetary gear trains 4A-4C driven by an output force of an engine, a plurality of friction devices B1-B4 and C1-C3 receiving hydraulic pressure to selectively connect or fix components constituting planetary gear trains 4A-4C, and a mechanical shift valve 6A having a pair of pressure chambers 62A and 63A and plural ports 64A, 65A and 66A. Upon application of hydraulic pressure to pressure chamber 62A, a fluid communicating path is established in the shift valve 6A so as to connect brake B1 and manual shift valve 8. When hydraulic pressure is applied to both of pressure chambers 62A and 63A, pressurized oil is drained from brake B1.

Abstract: Electronic and hydraulic control system of an automatic transmission for automotive vehicle and method for controlling hydraulic pressure whereby line hydraulic pressure can be compensated. A hydraulic pressure state within the electronic and hydraulic control system is precisely detected and the signal of this detected hydraulic pressure is transmitted to a transmission control unit such that the malfunction of the valves and the correct gear shifting stage can be determined. Since the hydraulic pressure state can be detected to be compensated by the control of the TCU, the shift quality can be improved.

Abstract: Disclosed is a hydraulic control system for an automatic transmission, including a hydraulic pump; a regulator valve for constantly regulating hydraulic pressure generated from said hydraulic pump; a reducing valve for reducing hydraulic pressure regulated by the regulator valve; a first-to-second speed shift valve for feeding hydraulic pressure to a friction member which is applied as a reacting element in a second speed; and a second-to-third/fourth-to-third speed shift valve for feeding hydraulic pressure to another friction member which is applied in third and fifth speeds. The first-to-second and second-to-third/fourth-to-third speed shift valves are respectively provided with control ports to which hydraulic pressure which is used for applying a friction member in fourth and fifth speeds is fed. The control ports are connected to a line, the line being provided with a shuttle valve.

Abstract: A hydraulic oil pressure changeover mechanism for switching an input pressure to a solenoid valve between a high pressure and a low pressure. The changeover mechanism is made up of: a pressure reduction valve to be switched between an operating condition for outputting a low hydraulic oil pressure and a non-operating condition for outputting a high hydraulic oil pressure; a changeover valve to be switched between a low-pressure position for inputting an output pressure from the pressure reduction valve to the solenoid valve and a high-pressure position for inputting a hydraulic oil pressure to be supplied without passing through the pressure reduction valve to the solenoid valve; and a control valve to be switched between a first position for outputting a first signal pressure to switch the pressure reduction valve to the non-operating condition and a second position for outputting a second signal pressure which operates in a direction to switch the changeover valve to the low-pressure position.

Abstract: A hydraulic control system of an automatic transmission, which includes a line pressure regulator for regulating the hydraulic pressure supplied from an oil pump to the hydraulic control line, and a shift structure for selectively delivering the regulated hydraulic pressure to the friction elements, wherein the shift structure further comprises a manual valve operatively linked with a shift lever for delivering the regulated hydraulic pressure according to shift ranges, a plurality of solenoid valves controlled on/off by a transmission control unit to control the friction elements, a first to a fifth pressure control valves for simultaneously controlling both releasing and connecting end of the friction elements, a first-to-second shift valve for making a port change by the hydraulic pressure flowing out from the pressure control valves to deliver the pressure to the friction elements, a forward drive clutch release valve, a second-to-third shift valve, and a reverse drive clutch valve.

Abstract: A hydraulic control system of automatic transmission for vehicles includes a torque converter control part having a damper clutch control solenoid valve and a regulator valve; a manual valve for supplying an oil pressure to another lines according to a shift lever's position; a first, a second, and a third indirect control valves, to which the oil pressure is supplied if the manual valve is set in drive "D" range; a first, a second, and a third solenoid valves, each of which controls the indirect control valves, respectively; a first friction element communicating with the first indirect control valve; a second friction element communicating with the second indirect control valve; a third friction element communicating with the second indirect control valve; a fourth friction element communicating with the third indirect control valve; a switch valve for supplying an operating pressure to the second friction element in drive "D" range and supplying the operating pressure to the third friction element in "L" r

Abstract: A hydraulic control system for an automatic transmission includes a regulator valve in a hydraulic circuit for supplying pressure to a servo of a frictional engagement element. The regulator valve has an input port, an output port and a drain port. A valve member of the regulator valve includes a pressure receiving area fed with a feedback pressure from the portion of the hydraulic circuit between the regulator valve and the servo, and another pressure receiving area selectively fed with pressure from a signal pressure source. A further pressure receiving area, having a surface area different from the another pressure receiving area, is constantly fed pressure from the signal pressure source.

Abstract: An oil pressure controller of an automatic transmission which is capable of supplying engaging pressures to hydraulic servos of two frictional engaging elements which require different engaging pressures by a single pressure governing valve with a good pressure governing accuracy. The oil pressure controller comprises a hydraulic power source (10), hydraulic servos (70 and 80), signal pressure generating means (20), a pressure governing valve (30) for governing an oil pressure (P.sub.s) from the hydraulic power source (10) by a signal pressure (P.sub.ACC) and a control valve (40). The pressure governing valve (30)has a pressure receiving face A.sub.1 to which the signal pressure is applied, a pressure receiving face A.sub.2 to which the engaging pressure (P.sub.s) is fed back in the opposite direction and a pressure receiving face (A.sub.

Abstract: A bearing support frame (4) is disposed within a rear end portion of a tractor front housing (1) and is fixedly supported by this housing which has an internal partition wall (1a) and an open rear end. An additional speed change mechanism (12) having plural fluid-operated clutches (54F, 54R) mounted on a primary shaft (7) of a high level which extends through the partition wall is disposed within a rear half of the front housing such that it is operable to perform a speed change transmission between the primary shaft and a co-axial output shaft (10) supported by the support frame. Fluid supply passages (55F, 55R, 55L) in the primary shaft are connected to fluid supply passages (61F, 61R, 61L) in the partition wall through annular fluid chambers (60F, 60R, 60L) defined between the primary shaft and a hollow cylindrical portion (37) of the partition wall.