Abstract: A vehicle control apparatus for controlling a control-subject component provided in a vehicle, by using a learning value of a control parameter which is obtained by a learning operation. The control apparatus includes an obtaining portion for obtaining information related to converged values of learning values of control parameters in a plurality of vehicles provided with respective control-subject components which are the same in type as the control-subject component provided in the vehicle, and a variation determination portion for determining whether a degree of variation among the converged values in the respective vehicles is smaller than a threshold value. The vehicle control apparatus causes the learning value to be converged by a smaller number of times of execution of the learning operation when the degree of the variation is smaller than the threshold value, than when the degree of the variation is not smaller than the threshold value.

Abstract: A gearbox (100) includes an input shaft (105) and a first and a second proportionally controllable shift element (A to F). The shift elements (A to F) are configured to control, by way of an open-loop system, engagement or disengagement of a gear ratio in the gearbox (100). A method (200) for the open-loop control of the gearbox (100) includes: determining a specified differential speed profile that is a profile of a difference between a rotational speed of the input shaft (105) and a synchronous speed of a gear ratio to be engaged; and determining a torque demand of a drive source connected to the input shaft (105) or determining a control profile for the one of the first and second shift elements (A to F) to be engaged in the gear ratio on the basis of the specified differential speed profile.

Abstract: A vehicle drive device includes a control portion that is allowed to execute a control mode that controls multiple hydraulic elements to cause a vehicle in a stop state of an engine to start moving. The control mode starts controlling part of the multiple hydraulic elements before the engine is started, by using oil pressure accumulated in an accumulator (S8). The control mode starts controlling the rest of the multiple hydraulic elements by using oil pressure that is provided after the engine is started (S16).

Abstract: A control device for a vehicle is provided, which vehicle includes a driving source, and an automatic transmission having a torque converter provided downstream of the driving source in a power transmission path and having a lockup clutch, and an engaging element provided downstream of the torque converter in the power transmission path. The device includes a control unit which engages the engaging element in a state where the lockup clutch is engaged if an accelerator opening becomes not smaller than a predetermined opening during neutral running control in which the automatic transmission is brought into a power shut-off state during running of the vehicle.

Abstract: A hydraulic control device with a second oil passage check valve provided in the second oil passage between a connection portion with the first oil passage and the second solenoid valve, the second oil passage check valve being configured such that a hydraulic pressure is supplied in a direction from the second solenoid valve toward the first oil passage and a hydraulic pressure is not supplied in the opposite direction.

Abstract: A control device that controls a vehicle drive device in which a rotary electric machine is provided in a power transfer path that connects between an internal combustion engine and wheels. Engagement of a second engagement device is started when a change in shift range from a stop range to a running range is detected when output torque of the rotary electric machine is zero with the internal combustion engine rotating and with both the first engagement device and the second engagement device disengaged. Engagement of a first engagement device is started after engagement of the second engagement device is started, and the output torque of the rotary electric machine is increased from zero at the same time as engagement of the first engagement device is started or before engagement of the first engagement device is started.

Abstract: A hydraulic control system is provided for controlling the actuation of a plurality of torque transmitting mechanisms. The hydraulic control system includes an accumulator having parallel feed paths to the plurality of torque transmitting mechanisms.

Abstract: A hybrid-driven hydraulic work machine maintains the torque of the engine at a prescribed value when the load on a hydraulic pump is higher than the rated power of the engine and the electric assist motor assists the torque of the engine. Control of the engine revolution speed is based on the target revolution speed of the engine; engine load calculation; and at least one of: electric motor power running calculation which calculates a differential revolution speed between the target engine revolution speed and the revolution speed of the engine and performs power running control on the electric assist motor depending on the differential revolution speed when the engine load is a prescribed value or higher; and a hydraulic pump absorption torque calculation which performs reduction control on absorption torque of the hydraulic pump depending on the differential revolution speed when the engine load is a prescribed value or higher.

Abstract: A system controlling gain in a control element includes a source of line pressure, a source of signal pressure, a control valve that controls communication between line pressure and the control element, including a first differential area communicating with control element pressure, and a second differential area, and a gain control valve that opens and closes communication between control element pressure and the second differential area in response to signal pressure.

Abstract: An axle assembly comprises a power transmission device including a housing having a cylindrically shaped sidewall. The power transmission device selectively communicates rotatable motion from an input member to an output member. A frictional clutch is disposed in the housing and includes a drum. A first and a second axle shaft selectively drive a first and a second drive wheel, respectively. A differential selectively transfers drive torque from the output member to at least one of the first and second axle shafts. An electric motor comprising a coil and a plurality of magnets is provided on the axle assembly. In one example, the coil is disposed on the housing and the magnets are disposed on the drum. The coil is configured to selectively energize to provide one of a positive or negative torque input to the output member.

Abstract: A system and method for controlling an accumulator in a transmission of a motor vehicle includes the steps of determining whether the motor vehicle has been turned off, sensing at least one operating condition of the motor vehicle, and comparing the at least one operating condition to a reference condition. If the at least one operating condition of the motor vehicle fulfills the reference condition and if the motor vehicle has been turned off then the accumulator is discharged.

Abstract: A system and method for controlling automatic stop-start of a motor vehicle is provided. The system and method is configured to enable an automatic stop-start mode of operation that minimizes clutch fill during engine restart.

Abstract: A hydraulic control system for actuating at least one torque transmitting device in a transmission includes a sump, a pump in communication with the sump, and an accumulator. A first control device and a second control device control the communication of hydraulic fluid between the pump, the accumulator, and the torque transmitting device.

Abstract: A power transmission configured with a mechanical pump that generates and deliver a fluid pressure to a clutch. An electromagnetic pump generates and delivers a fluid pressure to the clutch, and an accumulator connects the clutch and the electromagnetic pump, and accumulates fluid pressure acting there between. A switching valve selectively switches between connecting the mechanical pump side and the clutch in a fluid communicating manner and connecting the electromagnetic pump and the clutch in a fluid communicating manner. A valve drive portion that drives the switching valve so as to connect the mechanical pump side and the clutch when the mechanical pump is driving, and drives the switching valve so as to connect the electromagnetic pump and the clutch when the electromagnetic pump is driving in place of the mechanical pump.

Abstract: A hydraulic control system for actuating at least one torque transmitting device in a transmission includes a sump, a pump in communication with the sump, and an accumulator. A first control device and a second control device control the communication of hydraulic fluid between the pump, the accumulator, and the torque transmitting device.

Abstract: A hydraulic or pneumatic control device for an automated shift transmission including actuating devices with actuating cylinders (15, 16) having pressure spaces (19a, 19b; 20a, 20b). The pressure spaces (19a, 19b; 20a, 20b) of the actuating cylinders (15, 16) can be connected by a respective control valve (22a, 22b; 32a, 32b) to a pressure line (26), which can be selectively connected to or cut off from a main pressure line (8) by a main shut-off valve (45a). At least one additional main shut-off valve (45b) is arranged in parallel with the first main shut-off valve (45a) between the main pressure line (8) and the pressure line (26) to improve the control characteristics and increase the operational reliability.

Abstract: A hydraulic control system for actuating at least one torque transmitting device in a transmission includes a sump, a pump in communication with the sump, and an accumulator. A first control device and a second control device control the communication of hydraulic fluid between the pump, the accumulator, and the torque transmitting device.

Abstract: A hydraulically servocontrolled transmission for a road vehicle provided with an internal combustion engine; the servocontrolled transmission displays: a servocontrolled mechanical gearbox operated by at least one first hydraulic actuator; a servocontrolled clutch operated by at least one second hydraulic actuator; a hydraulic circuit comprising a hydraulic accumulator, which contains pressurised control fluid which is used by the hydraulic actuators, and a pump, which is directly operated by the internal combustion engine to supply pressurised control fluid to the hydraulic accumulator; a park-lock device operatable to block the rotation of the driving wheels; and a control unit, which, when the internal combustion engine is turned off, uses the remaining pressure of the control fluid within the hydraulic accumulator to bring the servocontrolled mechanical gearbox in a neutral position.

Abstract: The present invention provides a flow accumulator and a clutch control system for an automatic transmission. The flow accumulator includes a dual area piston disposed in a complementary dual diameter cylinder. The small end of the piston is pressurized by fluid from a spool valve which supplies and exhausts fluid to the clutch. The large end of the piston displaces fluid into the clutch when the small end is pressurized. A flow restricting orifice is disposed in parallel with the flow accumulator between the spool valve and the clutch and a pair of check valves control fluid flow into and out of the larger diameter cylinder.

Abstract: A device for operating a shifting element of a drive mechanism, having a piston positioned in a piston space to slide between first and second end positions. The piston is operated hydraulically and depends on the hydraulic pressure in the piston space and a force of a resetting mechanism acting on the piston, which opposes the activating force that is equivalent to the hydraulic pressure in the piston space. The transmission capacity of the shifting element is reduced by a force acting on the piston in the direction of the first end position and is increased by a force acting on the piston in the direction of its second end position. The piston is held by a mechanical holder against a force acting on the piston in the direction of the first end position in at least one preset position which is different from the first end position.

Abstract: A transmission control system includes a first gear engagement element that receives fluid and engages a first gear. An electromagnetic actuator selectively interrupts fluid flow to the first gear engagement element based on a duty cycle of a control signal. A control module adjusts the duty cycle so that a fluid flow rate continuously decreases as the first gear engagement element produces a first torque sufficient to hold the first gear. The flow rate is based on a first estimated volume of the fluid necessary for the first gear engagement element to produce the first torque. The control module computes a current volume of the fluid when the first gear engagement element produces the first torque. The control module adjusts a value of the first estimated volume for subsequent transmission control when a difference between the current volume and the first estimated volume is greater than a predetermined volume.

Abstract: A shift control apparatus for controlling shifting actions of an automatic transmission including a hydraulically operated frictional coupling device having a hydraulic cylinder which is supplied with a working fluid when the frictional coupling device is engaged, the shift control apparatus including a transient-hydraulic-pressure control device operable to control a transient value of a hydraulic pressure in the hydraulic cylinder according to an electric signal, upon releasing of the frictional coupling device, and an accumulator having a back-pressure chamber a back pressure of which is controllable, and an accumulator chamber connected to the hydraulic cylinder of the frictional coupling device and operable to control a transient value of the hydraulic pressure in the hydraulic cylinder, when the frictional coupling device is engaged with the working fluid being supplied to the hydraulic cylinder, and a back-pressure increasing portion operable to increase the back pressure in the back-pressure chamber o

Abstract: An apparatus for controlling a vehicle automatic transmission having a hydraulically operated frictional coupling device operable to effect a shifting action of the automatic transmission, and an accumulator connected to the frictional coupling device, the apparatus including an accumulator-back-pressure learning compensation device operable to effect learning compensation of a back pressure of the accumulator such that an actual value of a rate of change of a rotating speed of a selected rotary element of the automatic transmission, which rotating speed changes as a result of the shifting action, approaches a predetermined target value, and an accumulator-back-pressure control device operable to control the back pressure, on the basis of an output of the accumulator-back-pressure leaning compensation device, whereby a shifting shock of the transmission can be reduced.

Abstract: When a racing of engine occurred during a speed change, an oil pressure is forcibly supplied to a friction engagement element to be released, and a back pressure of an accumulator disposed in an oil supply pipe of this friction engagement element of release side is increased in stepwise.

Abstract: A method of controlling a hydraulic actuation system for an automated transmission system including, a hydraulic clutch actuator for controlling engagement of a clutch, a gear engagement actuator for controlling engagement of a gear, said gear engagement actuator being in the form of a double acting ram having first and second working chambers acting on opposite sides of a piston, a main control valve, the main control valve selectively connecting the clutch actuator and/or the gear engagement actuator to an accumulator or to a reservoir; a gear engagement control valve selectively connecting the first and second working chambers of the gear engagement actuator to the main control valve or to the reservoir; an electrically driven pump being provided to charge the spring accumulator, the pressure of fluid in the system being controlled by switching of the pump and connection of the clutch actuator to the accumulator.

Abstract: Shift valves 141, 142, 143 are provided to switch oil passage connections to a state in which an oil pressure in one hydraulic clutch of an arbitrary speed transmission train and an oil pressure in a hydraulic clutch of a transmission train which is adjacent thereto as seen in the order of speed are controllable by a pair of linear solenoid valves 201, 202. Skipped speed change from a predetermined first speed transmission train to a second speed transmission train which is not adjacent to the first speed transmission train is made possible. In concrete, a large-capacity accumulator A5 is connected to an oil passage L19 which is in communication with 5th-speed hydraulic clutch C5. At the time of skipped speed changing from 5th speed to 3rd speed, shift valves 141, 142, 143 are switched to a state of 3rd-4th speed change. The oil pressures in the hydraulic clutches C3, C4 for 3rd and 4th speed transmission trains, respectively, are made controllable by the linear solenoid valves 201, 202.

Abstract: A hydraulic circuit for an automatic transmission operable to reduce time delay in shifting includes a source supplying pressurized fluid through a feed orifice and a charging circuit including an accumulator. The accumulator is downstream of the feed orifice, and operates to reserve pressurized fluid supplied by the source. The hydraulic circuit also includes a clutch circuit, downstream of the charging circuit, which has a clutch hydraulically actuated and operable to generate torque to shift the automatic transmission. A valve is interposed between the charging circuit and the clutch circuit to open a flow path therebetween to start a shift cycle of the clutch. When the valve is actuated, the pressurized fluid is released from the accumulator and flows to the clutch circuit to minimize delay in the shift.

Abstract: A hydraulic circuit for an automatic transmission operable to reduce time delay in shifting includes a source supplying pressurized fluid through a feed orifice and a charging circuit including an accumulator. The accumulator is downstream of the feed orifice, and operates to reserve pressurized fluid supplied by the source. The hydraulic circuit also includes a clutch circuit, downstream of the charging circuit, which has a clutch hydraulically actuated and operable to generate torque to shift the automatic transmission. A valve is interposed between the charging circuit and the clutch circuit to open a flow path therebetween to start a shift cycle of the clutch. When the valve is actuated, the pressurized fluid is released from the accumulator and flows to the clutch circuit to minimize delay in the shift.

Abstract: A control apparatus for a hydraulically operated vehicular transmission having a plurality of speed change steps includes a shift valve unit controlling the supplying of hydraulic oil to and discharging of hydraulic oil from hydraulic pressure coupling elements for the respective speed change steps, a throttle hydraulic pressure signal outputting device which outputs a throttle hydraulic pressure signal which is applied to switch the shift valve unit, according to a throttle opening degree of an engine and an accumulator connected to an input oil path through which the throttle hydraulic pressure signal is applied to the shift valve unit.

Abstract: An automatic transmission control system having a hydraulic control circuit for supplying operating pressure selectively to a plurality of friction coupling elements to place the transmission in desired gears includes a pressure generator for generating operating pressure and supplying it to specific coupling elements which operate in response to operating pressure at different highest levels and an accumulator having a spring loaded piston which provides an increase in operating pressure at a rate variable according to movement of the piston, the rate being greater for greater piston movement as compared with for smaller piston movement, the accumulator being brought into communication selectively with the specific coupling elements by means of a switching element.

Abstract: It is detected on the basis of a change in an engine speed whether an out-of shelf condition in which a gear shft time exceeds a predetermined time is caused or not (step S11), and when the out-of shelf condition is caused, a lapping control processing corresponding to first engaging oil pressure setting means is executed so that a correction value is set to increase a line pressure supplied to each kind of engaging elements of an automatic transmission, and that the correction value is decreased as a gear shft load time elapses. At the same time, a learning control processing corresponding to a second engaging oil pressure setting means is executed (step S17) so that a variation of the engaging oil pressure due to the non-uniformity of engaging elements and the deterioration with age is learned, thereby to enable to automatically act a proper line pressure on each kind of engaging elements when either one of the automatic transmission or a controller which controls the automatic transmission is replaced.

Abstract: An upshift is effected by releasing an engaged first friction element and engaging a released second friction element. The first fiction element operates on a fluid pressure applied thereto through a first passage and the second friction element operates on a fluid pressure applied thereto through a second passage. An accumulator is provided in the first fluid passage. The accumulator has a back pressure port through which a back pressure is applied thereto by the function of a control valve having a first port connected to the back pressure port, a second port connected to a source of back pressure and a third port connected to a drain. The control valve operates, between a first position connecting the first port to second port and a second position connecting the first port to the third port, on first and second working signal pressures applied thereto.

Abstract: An upshift control device for an automatic transmission is provided in which the transmission is shifted up by releasing an oil pressure from a first engaging element that has been engaged while applying an oil pressure to a second engaging element that has been released.

Abstract: An up-shift control apparatus includes an engine racing detecting means for detecting engine racing during an up-shift and an engine racing preventing means. The up-shift control apparatus is installed to an automatic transmission which executes the up-shift by disengaging a first friction element and by engaging a second friction element. The engine racing preventing means outputs a command signal to a valve actuator to temporally increase an engagement force of the first friction element when the engine racing is detected during the up-shift.

Abstract: A control system for an automatic transmission having at least a friction coupling element which is coupled with a hydraulic pressure increasing by way of a leveled transitional pressure has an accumulator which discharge a high level of pressure accumulated therein into the friction coupling element during a gear shift under the condition where the line pressure is low.

Abstract: A hydraulic control system for an automatic transmission to establish a predetermined stage by applying a first frictional engagement element and releasing a second frictional engagement element, comprising: a first hydraulic servo for actuating the first frictional engagement element; a second hydraulic servo for actuating the second frictional engagement element; change-over means for switching the feed of an oil pressure to the first hydraulic servo; signal pressure generating means for generating a signal pressure; and a pressure regulator valve for regulating the pressure to be fed to the second hydraulic servo.

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 circuit for a hydraulically operated vehicular transmission has at least five forward transmission trains. The hydraulic control circuit is made up of three sets of first through third solenoid valves and three sets of first through third shift valves to be controlled for changeover by the three sets of solenoid valves such that each of the transmission trains is established by changeover combinations of each of the shift valves. The first shift valve controls a condition of communication between an oil supply passage which is in communication with a hydraulic oil pressure source and a first oil passage and a second oil passage which are both on a downstream side of the oil supply passage.

Abstract: An automatic transmission control system for selectively locking and unlocking a plurality of frictional coupling elements is provided within an automatic transmission so as to place the automatic transmission into one of various possible gears. The control locks a specific one of the frictional coupling elements with locking pressure when the automatic transmission performs a specific gear shift and unlocks it by reducing the locking pressure when causing it to perform, an opposite gear shift reverse to the specific gear shift. The locking pressure is increased by way of a relatively high level of shelf pressure during the specific gear shift and reduced by way of a relatively low level of shelf pressure during the opposite gear shift.

Abstract: A controller for an automatic transmission which reduces wear of frictional engagement elements and shortens gear change time even when a gear change jump is made. The controller of the present invention includes a first hydraulic servo to which oil is supplied to make a gear change jump, a second hydraulic servo to which oil is supplied to make a gear change to an intermediate gear stage, a limited supply oil circuit having an oil flow limiting element, a quick supply oil circuit bypassing the oil flow limiting element and a pressure governor for regulating a line pressure to supply oil at a controlled pressure to the quick supply oil circuit. An oil path switching valve switches oil supply, to the first hydraulic servo or the second hydraulic servo, between the limited supply oil circuit and the quick supply oil circuit.

Abstract: A control apparatus for a hydraulically operated vehicular transmission having a plurality of hydraulic engaging elements has an accumulator which is connected in parallel with a hydraulic engaging element for a low-speed transmission train and a back pressure generating source which generates a hydraulic oil pressure to be supplied to a back pressure chamber of the accumulator. The control apparatus includes a changeover valve which can be changed over between a first position in which the back pressure chamber of the accumulator and the back pressure generating source are brought into communication with each other and a second position in which the communication is cut off to lower a pressure in the back pressure chamber. The changeover valve is arranged to be changed over from the second position to the first position when a hydraulic oil pressure in the hydraulic engaging element for the low-speed transmission train has exceeded a predetermined pressure.

Abstract: An automatic transmission control system has first and second hydraulic circuits leading to a low/reverse brake and a reverse clutch, respectively, which perform supplying and discharging of hydraulic pressure to the low/reverse brake and reverse clutch, respectively, so as to lock and unlock them. The first circuit is provided, from the upstream end, with an orifice for restraining hydraulic pressure, an accumulator disposed downstream from the orifice for pressure accumulation, and a switching valve for switching supply and discharge of the hydraulic pressure. The second hydraulic circuit is provided, from the upstream end, with a switching valve for switching communication of the first hydraulic circuit between the orifice and switching valve with the second hydraulic circuit and communication of the first hydraulic circuit upstream from the orifice with the second hydraulic circuit.

Abstract: A valve is provided in one of the accumulator oil passageways provided between the servo and the 2-3 shift valve of an automatic transmission to partially restrict or control the flow of oil to and from the servo and clutch, thus adjusting the timing of shifts from second to third gear. The added valve or metering device would allow for a size increase of an orifice from the manual valve while maintaining proper timing of the apply/release of the 3-4 clutch and 2-4 band. The invention allows larger oil volume for both apply/release of the 3-4 clutch and 2-4 band, decreasing clutch failures and increasing transmission life expectancy. The invention is particularly advantageous with THM 700-R4 and 4L60-E automatic transmissions for 4-, 6- or 8-cylinder vehicles.

Abstract: A transmission control wherein modulating solenoid valves provide for continued governor and accumulator trim boost in the event of a malfunction in either the electrical or the hydraulic system. The transmission control provides redundancy to permit continued operation in the event one of the modulating solenoid valves fails. A single interlock valve is employed to prevent the two modulating solenoid valves from pressurizing the governor and the trim boost circuits when the transmission is operating in the reverse drive range.

Abstract: A hydraulic control for an automatically shifted power transmission has an electronically controlled governor pressure source which provides a speed and throttle sensitive pressure for controlling the shift points and trim boost in the transmission control. An inhibitor circuit is activated in the event of a discontinuance of the electrical control, resulting in maximum governor pressure, to permit selected vehicle operation in one forward ratio and a reverse ratio. Each ratio interchange is controlled by a respective shift valve and clutch control valve. Each clutch control valve has an integral trim control which is effective to control the pressure rise in the on-coming clutch without bypassing fluid to an exhaust. Also during a ratio interchange, an off-going clutch is controlled at a reduced pressure during a portion of the ratio interchange.

Abstract: An improved adaptive transmission pressure control in which cumulative adaptive corrections are stored in a multi-cell memory array, the cells being associated with specified contiguous ranges of a vehicle operating parameter, such as engine throttle position. Periodically determined adaptive correction amounts are applied to a selected cell which includes the engine throttle setting measured at the initiation of the shift and to two or more cells associated with contiguous engine throttle ranges. In this way, a relatively large number of cells may be employed to minimize approximation errors, while maintaining a cell-to-cell continuum of pressure correction values. In operation, an electro-hydraulic pressure regulator is controlled as a combined function of a predefined pressure command obtained from a normal table look-up and a cumulative correction amount obtained from the memory array.

Abstract: An automatic transmission control system includes a hydraulic circuit for controlling coupling pressure supplied to frictional coupling elements of the automatic transmission, which are selectively coupled and uncoupled so as to shift the automatic transmission into desired gears. The hydraulic circuit has a solenoid valve, for regulating a principal hydraulic pressure to provide a control pressure in accordance with vehicle driving conditions. The coupling pressure, supplied to a frictional coupling element, is regulated by a regulating valve in accordance with a control pressure level, and during shifting of the automatic transmission, is supplied through an accumulator whose back pressure is controlled in accordance with the control pressure by a control valve.

Abstract: An automobile automatic transmission shift control system, for causing a specific gear shift by unlocking a first frictional element with a simultaneously with locking a second frictional element, discharges locking pressure from the first frictional element in such a way that the locking pressure is throttled after it has dropped below a specified level of pressure.

Abstract: A multi-speed transmission has a hydraulic control system for establishing a plurality of forward drive ratios and a reverse drive ratio. Each drive ratio is established by the engagement of a fluid operated friction device, such as a clutch or brake. The engagement timing of each friction device is controlled in part by an accumulator. Each accumulator is disposed to accommodate friction devices, such that five forward speed and one reverse speeds require only a maximum of three accumulators.