Abstract: A driving apparatus includes a first transmission mechanism receiving mechanical power from an engine output shaft by a first input shaft, a second transmission mechanism receiving the mechanical power from the engine output shaft and a motor by a second input shaft, and a first clutch capable of engaging the engine output shaft with the first input shaft. When performing cranking of an internal-combustion engine, an ECU selects a gear position of the first transmission mechanism and the second transmission mechanism to reduce speed of the mechanical power received by the second input shaft and transmit the power to the first input shaft, and puts the first clutch into an engaging state. The speed of the mechanical power from the motor is reduced by the first and second transmission mechanisms to increase torque, and power is transmitted to the engine output shaft through the first clutch.

Abstract: The present disclosure utilizes Non-linear Proportional and Derivative (NLPD) control on a duty cycle of an applying clutch for stationary and rolling vehicle garage shifts. The applying clutch can be engaged by as electrically activated solenoid valve, and the present disclosure utilizes NLPD control to adjust the duty cycle of the solenoid to provide a smooth vehicle garage shift engagement. The present disclosure utilizes a control algorithm based on turbine speed, turbine acceleration, and output speed. The present disclosure can utilize an existing vehicle control unit, such as an engine control unit (ECU), transmission control unit (TCU), or the like, to receive turbine speed measurements, to calculate the solenoid duty cycle using NLPD control on the turbine speed acceleration error, and to adjust the solenoid driver on the solenoid valve.

Abstract: An ECU executes a program including: a step of detecting a turbine revolution speed, a step of detecting an engine torque TE, a step of detecting a speed change ratio, a step of setting a range an enlarged slip region when a slip region enlargement condition is satisfied, and a step of enlarging the slip region toward a lock-up region side (high-load side).

Abstract: An exemplary embodiment includes a method of operating a drivetrain. The drivetrain includes a PTO and a transmission having multiple speed ratios. The PTO includes a PTO output member and a PTO input member. The method includes monitoring a speed value representative of a rotational speed of a PTO component, comparing the speed value to a preselected PTO overspeed value, reducing the rotational speed of the PTO component, and overriding a manual command to increase the rotational speed of the PTO component above the preselected PTO overspeed value.

Abstract: The degradation of a feeling of ride is prevented by preventing engagement/disengagement (sudden engagement/disengagement) of a motorcycle hydraulic clutch due to a lack of hydraulic pressure. Before a hydraulic sensor issues a hydraulic pressure-lowering detection signal Sx, an oil level sensor issues an oil level-lowering warning signal Sf in a state wherein a sufficient oil quantity is such so as not to bring an neutral drive switching clutch into a disengagement state is present even if hydraulic pressure lowers resulting from an inclined oil level due to sudden deceleration, sudden start, drive in a slope, or the like. Thus, the neutral drive switching clutch can be prevented from disengaging or engaging (suddenly disengaging or engaging).

Abstract: A control apparatus of an automatic transmission including a start intended operation detecting unit detecting a vehicle starting operation; and a clutch control unit engaging the clutch from the clutch disengaged state and the automatic speed change mechanism is placed in a neutral state, when the vehicle starting operation is detected. The clutch control unit includes an initial engagement control unit performing initial engagement control that starts frictional contact of the clutch by supplying hydraulic pressure to a hydraulic servo of the clutch, and a slip start control unit establishing a speed ratio of the automatic speed change mechanism at the start by slip-controlling the clutch after the initial engagement control is terminated, thereby increasing output shaft rotational speed of the automatic speed change mechanism without reducing the input shaft rotational speed of the automatic speed change mechanism to less than the input shaft rotational speed at the end of initial engagement control.

Abstract: A method for controlling a transmission in a motor vehicle during acceleration from an idle condition begins when the vehicle is stationary, the engine is at idle, and the transmission is in the first gear range or ratio. When the vehicle begins to accelerate, the method includes the steps of monitoring the rate of vehicle acceleration and comparing the rate of vehicle acceleration to a rate of vehicle acceleration threshold. If the rate of vehicle acceleration is less than the acceleration threshold, then the transmission allows one of the currently engaged clutches to slip. This clutch slip reduces the torque load on the engine. The method then monitors the engine output speed. If the engine output speed exceeds an engine output speed threshold, then the clutch is fully applied.

Abstract: If it is determined that a D range is in use and determined that a vehicle is stopped, neutral control means (25) commands and controls an engagement pressure of a clutch (C-1) so as to achieve a state in which a piston of the clutch (C-1) contacts a clutch drum by a biasing force of a spring, and a state in which oil fills an oil passage from a linear solenoid valve (SLC1) to a hydraulic oil chamber and fills the hydraulic oil chamber. There is thus no drag loss in the clutch (C-1) during a neutral control, and the same fuel economy as when, for example, a manual shift to the neutral range is made can be achieved during the neutral control.

Abstract: A control system for an automatic transmission coupled to an engine by a torque converter includes a torque module and a first clutch control module. The torque module determines an input torque to the transmission based on an output torque of the engine. The first clutch control module adjusts an acceleration of a turbine of the torque converter during a down shift of the transmission based on the input torque. The first clutch control module adjusts the acceleration of the turbine by adjusting a first pressure of fluid supplied to an off-going clutch of the transmission based on the input torque. The first clutch control module adjusts the first pressure based on a mathematical model that relates a torque capacity of the off-going clutch, the input torque, and the acceleration. A method is also provided.

Abstract: A method for operating a control unit, such a control unit, and a computer program and computer program product for implementing the method are provided. In this context, the control unit is able to assume multiple states, a transition state being interposed during the transition from a first state to a second state.

Abstract: A control apparatus of an automatic transmission having an automatic speed change mechanism for changing a driving source speed of rotation and a clutch engaged at a start, a fluid transmission apparatus between the driving source and the automatic speed change mechanism, and a lock-up clutch for locking up the fluid transmission apparatus.

Abstract: An ECU executes a program including causing a brake to enter an engaged state, when first gear is implemented and when a difference between an output shaft rotation speed estimated from an input shaft rotation speed and a detected output shaft rotation speed is greater than a threshold value. When the brake enters the engaged state, the relative rotation between the inner race and the outer race of a one-way clutch is limited.

Abstract: A power transmission gearbox for rotorcraft for transmitting rotary movement from at least two engine members to a main shaft, wherein the gearbox presents at least two transmission systems for imparting rotary movement to the main shaft, each of the transmission systems including: an inlet shaft designed to be driven in rotation by an engine member; at least two reduction stages presenting different reduction ratios; a first gearwheel connected to the inlet shaft via a declutchable freewheel, the gearwheel meshing with a first toothed wheel secured to an intermediate shaft defining at least a first reduction stage; a second gearwheel connected to the inlet shaft via a simple freewheel, the second gearwheel meshing with a second toothed wheel secured to the intermediate shaft defining the second reduction stage; a main freewheel mounted on the intermediate shaft to rotate a complementary toothed wheel secured to the main shaft; and a clutch mechanism for the declutchable freewheel.

Abstract: A method of determining an engagement position of a clutch of a vehicle is provided. The clutch is operable by a clutch pedal adapted to move over a travel range. The method comprises determining a rate of change of position of the clutch pedal, locating a dwelling range of the clutch pedal, the dwelling range comprising a plurality of positions of the clutch pedal along the travel range during which the rate of change of position of the clutch pedal is less than a predetermined rate of change for a predetermined length of time, and recording the travel positions of the clutch pedal in the dwelling range.

Abstract: An oil pressure control device for a transmission engages or disengages a frictional engagement element of the transmission by controlling an oil pressure supplied from a mechanical oil pump driven by a power source for driving a vehicle and an electric oil pump driven by an electric motor, and includes: an air entering determining unit which determines whether or not air enters the electric oil pump; and an air discharging unit which, when an ignition switch of the power source is switched from an ON state to an OFF state after the air entering determining unit has determined that air enters the electric oil pump, drives the electric oil pump such that the air entering the electric oil pump is discharged from the electric oil pump together with an oil.

Abstract: A control system and method for an electromagnetic clutch brake, including an electromagnetic clutch brake actuator coil surrounding a power input shaft for a multiple-ratio transmission in a vehicle powertrain. A protective circuit of the control system normally monitors data inputs from a databus that may indicate conditions that are not favorable for clutch brake actuation. The protective circuit prevents actuation of the clutch brake under such conditions. In the event the data inputs are not available from the databus, the protective circuit permits operation in a fall-back mode in which a brake ON timer is checked prior to clutch brake actuation. A primary counter is incremented with each normal clutch brake actuation and a secondary counter is incremented with each fall-back clutch brake actuation.

Abstract: An overspeed system for a vehicle is disclosed. The overspeed system may have a power source, a transmission unit, and a torque converter assembly operatively coupling the power source to the transmission unit. The overspeed system may also have a travel speed sensor configured to generate a signal indicative of a vehicle speed, and a controller in communication with the torque converter assembly and the travel speed sensor. The controller may be configured to prevent a decoupling of the torque converter assembly in response to the signal.

Abstract: A method and device for dual-channel transmission of safety-relevant sensor signals. In the method, two sensor signals to be monitored are generated parallel to one another by two sensors and the generated sensor signals are transmitted to a common evaluation unit via two separate, input-side transmission channels. Within the evaluation unit, the permissibility of the transmitted sensor signals is checked using prescribed calculation specifications that correspond to one another and an evaluation unit output signal representing permissibility or impermissibility is generated for each sensor signal. The individual processing steps of the two calculation specifications are decoupled by the evaluation unit for the two sensor signals and performed diversified within the evaluation unit. The generated output signals are output via two separate, output-side transmission channels.

Abstract: A secondary drive device of a mobile working appliance with an electronic control unit for actuating a power take-off shaft clutch arranged between a transmission and a power take-off shaft is disclosed, according to the invention the control unit being designed with a flange-mounting function unit which, when activated, executes a rotary position correction of the power take-off shaft with respect to the drive shaft.

Abstract: An ECU executes a program including causing a brake to enter an engaged state, when a first gear is implemented and when a difference between an output shaft rotation speed estimated from an input shaft rotation speed and a detected output shaft rotation speed is greater than a threshold value. When the brake enters the engaged state, the relative rotation between the inner race and the outer race of a one-way clutch is limited.

Abstract: The present invention provides an apparatus and method for estimating the realtime position of a clutch piston during the fill cycle using noisy pressure measurements which ensures proper and desired clutch operation. Pressures on both sides of a flow controlling orifice, at the fluid control actuator and the clutch cylinder are measured and these measurements in conjunction with other system parameters such as orifice size, clutch volume and return spring characteristics are used to solve nonlinear dynamic equations (algorithms) which reside in a microprocessor. The microprocessor provides outputs corresponding to an estimate of the current position of the clutch piston, an estimate of the current speed of the piston and an estimate of the current hydraulic pressure. The method can also be utilized to detect clutch wear.

Abstract: A method for controlling a transmission input clutch during a vehicle launch includes selecting a subject device that transmits torque between an input and an output, a providing a mathematical model of the subject device, such that the model employing only static relationships of engine speed and transmission input speed to a desired magnitude of torque produced by the subject device, using the model, the current engine speed and the current engine speed to determine the desired torque produced by the subject device, and adjusting the torque capacity of the clutch to the desired torque of the subject device determined from the model.

Abstract: A method controls a friction clutch disposed between an internal combustion engine and a change speed transmission. The friction clutch is controlled in such a way that it transmits an average coupling torque of the internal combustion engine and does not transmit periodically occurring peak values of the coupling torque. In addition, a control unit is programmed to carry out the method.

Abstract: A method for determining a torque characteristic of a friction clutch located in a drive train of a motor vehicle in the force flow between a drive engine and a transmission and which is closed in its rest position. At least two marker points of a regulating-path-dependent torque characteristic are determined, one of which is determined at a slipping limit of the clutch. To enhance determination of the torque characteristic, a first marker point is determined with the clutch engaged, the transmission in neutral and the engine running, by slowly disengaging the clutch until a reduction in the speed of the transmission input shaft relative to the engine speed is detected. A corresponding pair of values of this marker point with the known braking torque of the input shaft and the set position are used for adapting an existing characteristic.

Abstract: A start control device and a start control method of a vehicular power transmission system including a lock-up clutch and a start clutch are provided in which start-time lock-up slip control is performed, and neutral control is performed. When the start-time lock-up slip control is additionally executed during cancellation of the neutral control, the gradient of an output rotational speed of the hydraulic power transmission which is changed, through engagement of the start clutch, toward an input rotational speed of the automatic transmission at the time of completion of engagement of the start clutch is controlled, using at least one of a start clutch pressure that is increased so as to engage the start clutch, and a lock-up clutch pressure that is increased so as to bring the lock-up clutch into slip engagement.

Abstract: A method of engaging a converter lock-up clutch in a power-shift transmission of a working machine. According to the method, the available engine torque or the turbine torque is determined, prior to an engagement of the converter lock-up clutch, and, depending on the determined engine torque or the determined turbine torque, the gradient of the engine torque is controlled by the transmission control unit during engagement and optionally controlled for a defined period of time following engagement such that acceleration of the vehicle, and thus a jerking sensation upon engagement of the converter lock-up clutch, is reduced or prevented.

Abstract: A clutch controlling apparatus includes a shift change transmission having a plurality of gear trains between a main shaft on an input side and a countershaft on an output side. A clutch controls transmission of power between the shift change transmission and an engine between engagement an disengagement. The clutch controlling apparatus automatically controls the clutch upon shift change of the shift change transmission. An input power ratio is calculated as a ratio between a rotation of the engine and a rotation of the countershaft. If the input/output power ratio exceeds a predetermined value in a direction of a rise of the rotation of the engine during shift change of the shift change transmission, a target control amount of the clutch is corrected in a clutch engagement direction.

Abstract: A system and method for transferring torque from a prime mover to a transmission includes a coupling device, a hydraulic control system and a control module. The coupling device includes a torque converter clutch (TCC), where the coupling device is located between an output of the prime mover and an input of the transmission. The TCC is actuated between a fully engaged position, a slip mode where slip occurs, and a fully disengaged position. The hydraulic control system includes a controller device that communicates an actuation pressure to the TCC. The actuation pressure actuates the TCC between the fully engaged position, the slip mode, and the fully disengaged position. The controller is in communication with the TCC, the output of the prime mover, the input of the transmission, and the controller device of the hydraulic control system. The controller regulates the actuation pressure.

Abstract: There is provided a method and apparatus to determine operating conditions for a powertrain comprising an internal combustion engine and first and second electrical machines and an electro-mechanical transmission selectively operative to transmit torque therebetween. The method comprises determining a torque output and an operating cost for operating the first and second electrical machines of the hybrid transmission effective to meet an operator torque request when the engine is operating in an engine-off operating state. Determining the torque output for operating the first and second electrical machines comprises executing a predetermined system equation effective to determine motor torque outputs from each of the first and second electrical machines based upon the selected parametric value for the input torque and the operator torque request.

Abstract: A torque converter clutch slip rate monitoring system includes a slip rate calculation module that receives a raw slip speed of a torque converter clutch and that calculates torque converter clutch slip acceleration based on the raw slip speed. A torque converter clutch slip rate monitoring module detects deviation of the slip acceleration from a predetermined range during a pulldown of the torque converter clutch.

Abstract: A method for controlling torque converter slip includes operating the torque converter in a controlled slip mode, monitoring slip in the torque converter, statistically analyzing the monitored slip to determine a likely condition of the torque converter, and utilizing the likely condition of the torque converter to control the torque converter slip.

Abstract: The invention starts from a transmission control device with a control unit (10) which, to eliminate a tooth-on-tooth position in a transmission shifting unit (11, 12), is designed to adjust a transmission clutch (13) to a nominal clutch value (KKick). It is proposed that in at least one operating mode the control unit (10) is designed to specify a prescribed clutch value (KDes) which is independent of any intermediate clutch value setting.

Abstract: A method for controlling a power-shift transmission comprising controlling a vehicle travel speed by simultaneously slipping two or more clutch packs associated with opposing directions of vehicle travel and adjusting an engine speed, according to a programmed response associated with a change in one or more of the engine speed, a torque converter slip, a selected direction of vehicle travel, and an accelerator position.

Abstract: A combined brake and clutch unit is provided for a drivetrain of a vehicle, such as a road vehicle, and a method is provided for operating the same. A brake ring is provided at a housing of a clutch which is enclosed by a brake actuator. The housing of the clutch is connected to a wheel axis and a clutch surface is connected to an axis of a vehicle. Furthermore, a multiplate clutch is provided for use as an interaxle differential.

Abstract: A control apparatus for a vehicular drive system including an electric differential portion and a mechanical power transmitting portion which are disposed in series in a power transmitting path between an engine and a drive wheel of a vehicle, the control apparatus being configured to limit an output of the engine according to a difference between an actual rotating speed of an input rotary member of the mechanical power transmitting portion, and a theoretical rotating speed calculated from an actual vehicle speed and a presently established speed ratio of the mechanical power transmitting portion, whereby reduction of torque capacity of an input clutch provided in the mechanical power transmitting portion does not cause an excessive rise of the rotating speed of a rotary member which is located on one side of the input clutch nearer to the engine, and an excessive rise of the rotating speed of an electric motor connected to the input rotary member.

Abstract: A dual clutch automated manual transmission includes a first clutch and a second clutch, and a clutch torque capacity command value for a plurality of clutch actuators arranged to drive the first clutch and second clutch based on operation of a by-wire type of clutch lever, wherein the clutch torque capacity of the plurality of clutches is controlled. An operator can adjust a driving force by manually operating the clutch in the transmission in which a clutch operation is controlled automatically, such as an automatic transmission system, automated manual transmission system, or dual clutch automated manual transmission system, thereby improving drivability.

Abstract: A method controlling a clutch arrangement that serves, in a powertrain of a motor vehicle, for the transmission of a torque from an input element to an output element. Starting from an activated state of the clutch arrangement, a respective estimated torque value is calculated in repeating calculation cycles. A torque build-up value is calculated in dependence on at least one speed difference value. A torque reduction value is calculated in dependence on at least the last calculated estimated torque value. The estimated torque value is re-calculated on the basis of the last calculated estimated torque value by up integration of the calculated torque build-up value and down integration of the calculated torque reduction value. The recalculated estimated torque value is compared with a torque threshold value. The clutch arrangement is deactivated when the recalculated estimated torque value is below the torque threshold value.

Abstract: In a control for a motor vehicle transmission having a clutch and means for establishing and/or releasing an engagement of a toothing or of jaws of the motor vehicle transmission including a control unit for actuating the clutch for transmitting a torque to a first component of the toothing, the control unit being adapted, for the purpose of releasing a tooth-on-tooth position of the toothing, to briefly provide a control signal for adjusting the clutch to a desired clutch position (KS) in order to generate a torque pulse, the control unit determining a reaction of the motor vehicle transmission in response to the control signal from the control unit and adapting the desired clutch position (KS) as a function of the reaction.

Abstract: A method of detecting substantial filling of a hydraulic cylinder of a hydraulically operated clutch of a vehicular transmission is disclosed and claimed. A pressure sensor disposed in a hydraulic line to the clutch cylinder provides a signal that the hydraulic pressure has dropped as the clutch cylinder begins to fill and also that the pressure has returned to a substantially normal level. The pressure sensor may be a continuously variable output such as an analog sensor, pulse width modulation (PWM) sensor, a similar device or, less desirably, a two state sensor. An iterative algorithm utilizes data from the sensor and a timer to determine when clutch fill is substantially complete.

Abstract: A method for determining a release bearing touch point in a clutch is described. A cross shaft of the clutch is positioned in a pre-determined state. A quantity of torque is applied to the cross shaft using an actuator and a velocity change is determined in the cross shaft. An angular position of the cross shaft is recorded when the velocity change happens as the new release bearing touch point.

Abstract: An automatic transmission calculates a current thermal load state of the frictional element, predicts (S41), prior to the start of the shift, a heat generation amount of the frictional element during the shift, predicts (S42) a thermal load state of the frictional element upon shift completion on the basis of the current thermal load state of the frictional element and the predicted heat generation amount, determines (S43, S44, S45) whether to permit or prohibit the shift on the basis of the predicted thermal load state upon shift completion, and halts the determination as to whether to permit or prohibit the shift, made on the basis of the predicted thermal load state upon shift completion, when a shift mode of the shift is a second shift mode in which the heat generation amount is smaller than that of a first shift mode.

Abstract: A method is proposed for triggering the clutch moment of a clutch of an automated gear in the power train of a vehicle with the creep function activated, where the clutch moment is triggered as a function of the slippage on the clutch and/or as a function of the speed of the vehicle. Furthermore, a device is proposed for triggering the clutch moment of a clutch of an automated gear, in particular, to implement the abovementioned method where at least one control device is provided which triggers the clutch moment as a function of the slippage on the clutch and/or as a function of the speed of the vehicle.

Abstract: A control method of shifting gear in an automatic manual transmission having a twin-clutch gearbox to pass from a current gear to a successive gear, the control method including the steps of receiving a command of gear shifting, opening a first clutch associated with current gear, closing a second clutch which is associated with successive gear and starts transmitting a torque after a delay time interval from the start of the closing, and starting the opening of first clutch, thus decreasing the torque transmitted by first clutch itself before second clutch starts transmitting a torque, such that first clutch decreases the torque transmitted to the driving wheels before the second clutch starts transmitting a torque to the driving wheels.

Abstract: The adjustment method includes an estimation step in which valve characteristics of the linear solenoid valves fitted to the hydraulic control circuit are measured, and estimated linear valve characteristics of the linear solenoid valves in isolation state are estimated based on the measured valve characteristics using predetermined correlations; and a correction value output step in which estimated linear piston-end pressures of the hydraulically-driven friction engagement elements immediately before the hydraulically-driven friction engagement elements are engaged are calculated based on the estimated linear valve characteristics, and the correction values that are applied to the control command values to adjust the drive currents supplied from the valve control unit to the linear solenoid valves are calculated based on differences between the estimated linear piston-end pressures and nominal piston-end pressures, and then output.

Abstract: A vehicle control method for a vehicle having an internal combustion engine coupled to a torque converter is described. In one embodiment, the engine air flow and spark are adjusted to control torque converter operation. The method can improve vehicle response to driver accelerator commands.

Abstract: A clutch engagement control system for a vehicle transmission. The system comprises an automatic transmission gearset and at least one hydraulic clutch coupled to the gearset. A hydraulic pressure controller is coupled to the clutch. A clutch engagement controller is coupled to the pressure controller, and an altitude sensor is coupled to the clutch engagement controller. The clutch engagement controller is configured to receive from the altitude sensor an altitude signal corresponding to the altitude of the vehicle. The clutch engagement controller adjusts a hydraulic pressure request of the pressure controller in accordance with the altitude signal, such that the clutch engages with at least one of a rate and pressure corresponding to the sensed altitude. A method employs the system.

Abstract: A riding type vehicle includes an automatic transmission capable of executing a shift change by a clutch actuator and a shift actuator. A clutch is controlled by the clutch actuator and is a multiplate clutch. The multiplate clutch is provided with bias member configured to enlarge a partial clutch engagement region of the clutch. The multiplate clutch is configured such that during shift change, both of the clutch actuator and the shift actuator are controlled to operate in overlapping manner.

Abstract: A method for controlling trapped air in a clutch of an automatic clutch-to-clutch transmission includes, calculating a pulse on time based on a clutch volume and adaptive convergence. A pulse off time is calculated based on a temperature of transmission fluid. A pulse number is calculated based on the temperature of transmission fluid. A maximum pressure is commanded to the clutch based on the pulse on time and a minimum pressure is then commanded to the clutch based on the pulse off time. A pulse counter is incremented when the pulse off time expires. The steps of commanding maximum pressure, then commanding minimum pressure, and incrementing the pulse counter are repeated until the pulse counter equals a desired pulse number.

Abstract: The invention relates to a method for controlling a coupling device between an input shaft driven by a motor and an output shaft that can transmit a maximum torque according to the position of an actuator of the coupling device 5 complying with a law of behavior of the coupling means according to which: a set value (Cemb,cons) of maximum torque to be transmitted is defined; the actual position (Xemb,mes) of the actuator of the coupling device is measured; a set value (Xemb,cons) is determined for actuating the coupling device and is sent to the actuator of the coupling device, while using a law of behavior of the coupling means obtained by interpolation between a first law of reference of behavior of the coupling means and at least one second law of reference of behavior of the coupling means, and; an auto-adaptation of the law of behavior of the coupling means is carried out for taking into consideration its evolution resulting from the use.

Abstract: A method of operating a clutch during vehicle launch including increasing a first hydraulic pressure in an inner chamber from a first to a second level; decreasing a second hydraulic pressure in an outer chamber from a third to a fourth level in response to engine speed and throttle position for the vehicle; and slipping the clutch in response to increasing and decreasing the first and second pressures, respectively. The first hydraulic pressure urges a clutch disposed between the engine and an impeller for a vehicle torque converter to an engaged position. The second hydraulic pressure opposes the first hydraulic pressure. In some aspects, the method includes determining a temperature for oil in a transmission in the vehicle. Then, decreasing the second hydraulic pressure includes decreasing the second pressure in response to the determined temperature. In some aspects, the clutch and the chambers are located in the torque converter.