Abstract: Methods and systems are provided for operating a driveline of a hybrid vehicle that includes an internal combustion engine, an electric machine, and a transmission are described. In one example, the engine is started and coupled to the driveline via closing a clutch of a dual clutch transmission. Speed of the engine and clutch pressure are controlled to reduce driveline torque disturbances and provide a desired wheel torque.

Abstract: A vehicle includes an engine and an electric machine coupled to a gearbox through a torque converter. The vehicle includes a controller programmed to command an engine torque and an electric machine torque to achieve a predetermined positive torque at the input of the torque converter when a driver demand torque at the torque converter input decreases to fall within a range between the predetermined positive torque and a predetermined negative torque.

Abstract: A control device includes a deceleration flex-torque calculation unit that calculates a target torque capacity of a lock-up clutch when a state of the lock-up clutch is controlled to a deceleration flex control state, an acceleration flex-torque calculation unit that calculates a target torque capacity of the lock-up clutch when the state of the lock-up clutch is controlled to an acceleration flex control state, and a control unit that controls a torque capacity of the lock-up clutch to a target torque capacity calculated by the acceleration flex-torque calculation unit, during a period until a target torque capacity calculated by the acceleration flex-torque calculation unit falls below a target torque capacity calculated by the deceleration flex-torque calculation unit, when the state of the lock-up clutch is shifted from the acceleration flex control state to the deceleration flex control state.

Abstract: A control device for a lockup clutch is provided in which when control region determination device determines that a vehicle speed and an opening degree of an accelerator pedal are in the tight region of the lockup clutch, even if the water temperature of cooling water of the or the oil temperature of hydraulic oil of the transmission is less than a predetermined temperature, engagement permission device permits engagement of the lockup clutch. It is therefore possible to improve the fuel economy of the vehicle by increasing the frequency of engagement of the lockup clutch without affecting the function of the lockup clutch. The control device even functions when the lockup clutch is engaged at low temperatures, when the engagement responsiveness is low, because the oil temperature of the hydraulic oil is low and the viscosity is high.

Abstract: A method for synchronizing a gear on a parallel-shafts vehicle gearbox shaft including at least one primary shaft connected to a power source, one secondary shaft driven by the primary shaft to transmit driving torque to wheels over plural transmission ratios, and at least one mechanism coupling a gear to its shaft to engage a transmission ratio without mechanical synchromesh members. The power source is made to operate to produce a signal commanding the reference torque (T1ref), equal to minimum torque that can be transmitted to minimize a discrepancy (?2K??1) between a primary speed (?1) and a secondary speed (?2) multiplied by a reduction ratio (K), when the relevant gear is coupled to its shaft, wherein the control signal is given by the sum (KwK?2?Ks?1+T1int), in which (T1int) is a term derived by integrating the primary speed (?1).

Abstract: A torque converter clutch control system of a vehicle includes a target slip module and a slip control module. The target slip module determines a target torque converter clutch slip based on an average number of activated cylinders of an engine during a predetermined period. The slip control module controls a torque converter clutch based on the target torque converter clutch slip.

Abstract: Systems and methods for improving operation of a hybrid vehicle are presented. In one example, driveline disconnect clutch operation is adjusted in response to vehicle mass so that the vehicle may operate similarly at lower and higher vehicle masses.

Abstract: A hydraulic control system for a dual clutch transmission includes a plurality of solenoids and valves in fluid communication with a plurality of clutch actuators and with a plurality of synchronizer actuators. The clutch actuators are operable to actuate a plurality of torque transmitting devices and the synchronizer actuators are operable to actuate a plurality of synchronizer assemblies. Selective activation of combinations of the solenoids allows for a pressurized fluid to activate at least one of the clutch actuators and synchronizer actuators in order to shift the transmission into a desired gear ratio.

Abstract: In a control apparatus for an automatic transmission, it is configured to calculate a change amount (?NC estimation value) of an output rotational speed of the transmission (S10); calculate an average (I phase initial average G) of the change amount of the output rotational speed over a predetermined period of an initial inertia (I) phase of shifting; calculate an average (after-shift average G) of a vehicle acceleration after the completion of the shifting, assuming that the change amount of the output rotational speed indicates the vehicle acceleration G; calculate a difference (I phase initial G) between the average of the change amount of the output rotational speed and the average of the vehicle acceleration; incrementally and decrementally correct the desired value of the transmission torque of the frictional engaging element such that the calculated difference falls within a predetermined range; and control supply of hydraulic pressure to the frictional engaging element such that it becomes the correct

Abstract: Methods and systems are provided for controlling a vehicle system including a selectively shut-down engine, a torque converter and a torque converter lock-up clutch. One example method comprises, during an idle-stop engine shut-down, restricting flow of transmission fluid out of the torque converter, and adjusting engagement of the torque converter lock-up clutch to adjust a drag torque on the engine to stop the engine.

Abstract: A method of estimating transmission torque of a dry clutch, may include a) slowly releasing a dry clutch until a slip of the dry clutch occurs, b) acquiring and storing stroke of an actuator and torque of an engine at a starting time point at which the slip of the dry clutch occurs at step a), and c) determining the stroke of the actuator and the transmission torque of the dry clutch at the starting time point at which the slip of the dry clutch occurs, by using the stroke of the actuator and the torque of the engine stored at step b).

Abstract: A control apparatus of a working vehicle including a hydraulic pump driven by an engine and two hydraulic motors connected in parallel to the hydraulic pump, a clutch being released or engaged so that a power is transmitted to one of the hydraulic motors via the clutch, includes: a load detection unit determining a load of the working vehicle from a throttle output amount and an engine speed of the engine; and a control unit reducing a pump injection amount of the hydraulic pump under an upper limit injection amount of the hydraulic pump predetermined based on the load at a time of release shift control of the clutch and increasing a pump injection amount of the hydraulic pump under a lower limit injection amount of the hydraulic pump predetermined based on the load at a time of engagement shift control of the clutch.

Abstract: A control system (100) for an all-wheel-drive torque transfer case (102) coupling of a motor vehicle (104) including a power unit (130) having a centrifugally governed fluid pump (132) and a flow valve (134) movable between recirculation and diverter positions (134a, 134b). A control valve (136) located between the fluid pump (132), the all-wheel-drive clutch assembly (112), and the range shift assembly (120). The control valve (136) operable between a first position (136a) allowing fluid flow between the pump (132) and the clutch assembly (112), and a second position (136b) allowing fluid flow between the pump (132) and the range shift assembly (120). At least one range shift valve (138; 152, 154) located between the control valve (136) and the range shift assembly (120).

Abstract: A hybrid drive apparatus includes an input member that is drivingly connected to a rotary electric machine and drivingly connected via an input clutch to an internal combustion engine, an output member that is drivingly connected to the input member and transmits rotation of the input member to wheels, and a control device that controls the rotary electric machine. The control device is capable of performing valve opening/closing phase control that advances or retards opening/closing phases of valve elements provided in the internal combustion engine via a valve opening/closing phase adjusting mechanism and, with the internal combustion engine in a stopped state before starting a vehicle, advances the opening/closing phases of the valve elements to bring the opening/closing phases of the valve elements into an advanced phase state relative to predetermined reference phases, thus starting the vehicle with torque of the rotary electric machine in the advanced phase state.

Abstract: A torque converter clutch control system of a vehicle includes a target slip module and a slip control module. The target slip module determines a target torque converter clutch slip based on an average number of activated cylinders of an engine during a predetermined period. The slip control module controls a torque converter clutch based on the target torque converter clutch slip.

Abstract: A transmission ECU 12 determines whether or not the conditions for executing a neutral control operation are satisfied (step S11), and measures hydraulic oil temperature if it determines that the execution conditions are satisfied (step S12). Then, the transmission ECU 12 sets a target speed ratio for a torque converter 3 corresponding to the measured hydraulic oil temperature (step S13), and performs a neutral control operation to bring the speed ratio of the torque converter 3 equal to the target speed ratio (step S14).

Abstract: A hybrid engine assembly may include an engine having a crankshaft, a supplemental shaft mechanically coupled to the crankshaft, a flywheel energy storage assembly, and an auxiliary device. A flywheel clutch may selectively couple the flywheel assembly to the crankshaft. The assembly may be selectively operated in an engine restart mode by directly coupling the flywheel energy storage assembly to the crankshaft prior to starting the engine, and in an auxiliary power mode by directly coupling the flywheel energy storage assembly to the auxiliary device.

Abstract: In a hydraulic control device, when a solenoid pressure from a linear solenoid valve is not supplied to a brake, which is normally not engaged at the same time as a brake, not to engage the brake, a switching valve is supplied with a line pressure as a signal pressure for establishing a blocked/discharge state in which supply of the solenoid pressure to the brake is blocked and a hydraulic pressure can be discharged from the brake. When the solenoid pressure is supplied to the brake to engage the brake, the switching valve is supplied with a modulator pressure, which is lower than the line pressure, as a signal pressure for establishing a communicated state in which the solenoid pressure can be supplied to the brake.

Abstract: A method and system are provided for controlling the operating temperature of a torque converter during torque converter stall conditions. The torque converter has a pump rotatably driven by an internal combustion engine and a rotatable turbine fluidly coupled to the pump. The system first determines whether the torque converter is currently in a torque converter stall condition, and, if so, determines a slip speed as a difference in rotational speeds between the pump and the turbine, determines an engine output torque limit as a function of the slip speed and a desired slip speed, and controls the operating temperature of the torque converter by limiting output torque produced by the engine based on the engine output torque limit.

Abstract: Methods and systems are provided for controlling a vehicle system including a selectively shut-down engine, a torque converter and a torque converter lock-up clutch. One example method comprises, during an idle-stop engine shut-down, restricting flow of transmission fluid out of the torque converter, and adjusting engagement of the torque converter lock-up clutch to adjust a drag torque on the engine to stop the engine.

Abstract: A control device for controlling an engagement state of a lock-up clutch is provided. A plurality of target slip ratio maps include a normal slip ratio map having a characteristic line of a target slip ratio defined in accordance with an engine load at a normal vehicle running condition and a modified slip ratio map having a characteristic line of the target slip ratio to become a facing calorific value lower than a facing calorific value corresponding to the slip ratio retrieved from the normal slip ratio map. In the case where an estimate value of the facing temperature continues to exceed first threshold temperature for more than predetermined time when to carry out slip control using the normal slip ratio map, control to switch the target slip ratio map from the normal slip ratio map to the modified slip ratio map is carried out.

Abstract: A control device for a lockup clutch is provided in which when control region determination means (M3) determines that a vehicle speed detected by a vehicle speed sensor (Sc) and an opening degree of an accelerator pedal detected by an accelerator pedal opening degree sensor (Sd) are in the tight region of the lockup clutch, even if the water temperature of cooling water of the engine detected by a water temperature sensor (Sa) or the oil temperature of hydraulic oil of the transmission detected by an oil temperature sensor (Sb) is less than a predetermined temperature, engagement permission means (M2) permits engagement of the lockup clutch, and therefore, it is possible to contribute to an improvement of the fuel economy by increasing the frequency of engagement of the lockup clutch without affecting the function of the lockup clutch.

Abstract: A clutch control device that controls a clutch by driving a piston using a working fluid, having: stroke start determining means (S1) for determining that a stroke of the piston has started and detecting a stroke start oil pressure at that time; stroke end determining means (S4) for determining that the stroke of the piston is complete and detecting a stroke end oil pressure at that time; stroke end range estimating means (S3) for estimating a range of the stroke end oil pressure from the stroke start oil pressure detected by the stroke start determining means; and learning means (S5, S6) for learning the stroke end oil pressure detected by the stroke end determining means when the stroke end oil pressure is within the estimated range of the stroke end oil pressure. Learning precision of the stroke end oil pressure can be improved.

Abstract: A control device for a vehicular lockup clutch, including a lockup clutch that directly connects an input rotation member and an output rotation member of a hydraulic transmission device constituting part of a power transmission path between an engine and drive wheels, a linear solenoid valve that controls an engagement hydraulic pressure for engaging and actuating the lockup clutch, and a controller that is configured to perform a flexible start control for slip-engaging the lockup clutch when a vehicle starts moving, and to perform, before starting the flexible start control, a precharge control for establishing a standby state in which a predetermined preparation pressure is indicated to the linear solenoid valve.

Abstract: A transmission includes a plurality of clutches that are selectively engageable alone or in combination with each other to establish a plurality of forward drive modes, wherein one of the clutches is configured as a neutral idle (NI) clutch that is selectively actuated to shift the transmission into an NI state, and a controller. The controller is adapted to shift the transmission from a forward drive mode into the NI state during a coast-down maneuver prior to the transmission reaching a zero output speed. A method of shifting the transmission into the NI state includes determining the presence of a predetermined one of the forward drive modes using the controller, and using the controller to actuate a designated one of the clutches as an NI clutch to enter the NI state during the forward drive mode, during a coast-down maneuver, and prior to the transmission reaching a zero output speed.

Abstract: The present invention relates to a hydraulic apparatus comprising a hydraulic machine comprising a machine shaft having a proximal end and a distal end, adapted to drive a cylinder block, a clutch comprising a clutch shaft having a proximal end and a distal end, and engaging means for selectively engaging said clutch shaft with said machine shaft, said engaging means comprising a plurality of friction discs linked to the distal end of the clutch shaft and a plurality of friction discs linked to the proximal end of the machine shaft, said discs being disposed radially around said machine shaft, characterized in that the distal end of said clutch shaft is bell-shaped so as to surround the proximal end of said machine shaft, said bell shape defining an inner space where the proximal end of the machine shaft and the friction discs linked to the clutch shaft are located.

Abstract: Systems and methods for improving operation of a hybrid vehicle are presented. In one example, a transfer function of a driveline disconnect clutch is adapted.

Abstract: Systems and methods for improving operation of a hybrid vehicle are presented. In one example, driveline disconnect clutch operation is adjusted in response to vehicle mass so that the vehicle may operate similarly at lower and higher vehicle masses.

Abstract: A method for engagement of an impeller clutch includes a process for decreasing a back pressure relative to a clutch engagement pressure by decreasing an internal pressure of a torque converter in a case where the impeller clutch is brought into an engaged state, the impeller clutch enabling a driving force of an engine to be transmitted and disconnected to and from a pump impeller of the torque converter, transmission and disconnection of the driving force between the engine and the pump impeller being controlled by the clutch engagement pressure that is applied to the impeller clutch through an independent oil passage.

Abstract: A drive device for a hybrid vehicle is provided with an engine and a motor generator. A one-way clutch is provided between the engine and the motor generator. Power is transmitted from the engine to the motor generator, while power from the motor generator to the engine is blocked. As a result, the electric motor can be operated without operating the engine. Furthermore, a torque converter is connected to the motor generator, and the engine is connected to the torque converter via a starting clutch. As a result, if a one-way clutch is provided, the motor generator can serve as a starter motor.

Abstract: An apparatus and method of controlling a torque transmitting apparatus having multiple selectively engageable couplers is provided. The multiple couplers may be selectively engaged and disengaged to provide a mechanical, friction or fluid coupling between portions of the torque transmitting apparatus and other components of a vehicle powertrain during various operational stages. The control apparatus includes a fluid pressure control device and a fluid flow control device.

Abstract: When shift transmission of an automatic transmission is performed in a free-run state, a driving force control apparatus controls a degree of engagement of an engaging device in accordance with a hydraulic difference between a first hydraulic pressure and a second hydraulic pressure in a condition that the first hydraulic pressure does not reach the second hydraulic pressure. As a result, an oil pump supplies a hydraulic pressure to the automatic transmission, and the shift transmission can be performed. The first hydraulic pressure is a hydraulic pressure of the automatic transmission. The second hydraulic pressure is a hydraulic pressure required to perform the shift transmission. The engaging device can adjust an extent of transmission power between an engine and the automatic transmission in accordance with the degree of engagement.

Abstract: A vehicle includes a clutch set, a tank with fluid, an auxiliary battery, an electric fuel pump, and a controller. The electric fluid pump delivers some of the fluid from the tank to a designated oncoming clutch of the clutch set. The controller calculates a predicted flow value for the oncoming clutch during the shift event, and selectively controls the speed of the pump using the predicted flow value during the shift event. The controller controls the pump using an actual flow value when the vehicle is not executing a shift event, i.e., when holding torque. The speed of the electric fluid pump is increased to a first calculated speed determined using the predicted flow value when the shift event is initiated and before filling of the oncoming clutch commences, and is reduced to a second calculated speed determined using the actual flow value when the shift event is complete.

Abstract: A hydraulic control system for a dual clutch transmission includes a plurality of solenoids and valves in fluid communication with a plurality of clutch actuators and with a plurality of synchronizer actuators. The clutch actuators are operable to actuate a plurality of torque transmitting devices and the synchronizer actuators are operable to actuate a plurality of synchronizer assemblies. Selective activation of combinations of the solenoids allows for a pressurized fluid to activate at least one of the clutch actuators and synchronizer actuators in order to shift the transmission into a desired gear ratio.

Abstract: A power transmitting apparatus for a vehicle mounted with a torque converter can be configured to instantly supply sufficient oil to a clutch mechanism on restart of the engine after an idle-stop without an electrically-driven oil pump. A power transmitting apparatus can comprise a torque converter having a torque amplifying function, a clutch mechanism, an oil pump, a clutch control device, an engine control device, and a flow control device. The oil pump can be driven by the driving power of the engine to supply oil to the clutch mechanism and the torque converter to operate them. The flow control device can be configured to limit or prevent the supply of oil to the torque converter by the oil pump and to prioritize the supply of oil to the clutch mechanism when the engine is restarted by the engine control device after the idle-stopped condition.

Abstract: A control device of a vehicle drive-train system including an engine, an electronic throttle valve, an automatic transmission having a manual shift mode, a torque converter provided between the automatic transmission and the engine, and a lock-up clutch operable to directly connect an input member and an output member of the torque converter with each other includes a blipping control device that performs blipping control for temporarily increasing the output rotational speed of the engine by of the electronic throttle valve, when a power-off downshift is performed while the automatic transmission is in the manual shift mode; and a lock-up control device that engages or partially engages the lock-up clutch, based on a difference between a rotational speed of the output member of the torque converter and a rotational speed of the input member thereof, which the difference is reduced after the blipping control is started.

Abstract: Systems and methods of driving and controlling pneumatic and hydraulic devices and, more particularly, to a system and method of driving a hydraulic pump via one output shaft of a motor, and driving a pneumatic compressor via another output shaft of the motor via a clutch. When a user control is engaged, a control system causes the motor to operate at a higher speed, driving the hydraulic pump faster to produce additional hydraulic pressure. When a low air pressure condition is sensed in the pneumatic system, the control system causes the motor to operate at the higher speed and engages the clutch, allowing the pneumatic compressor to supply additional air pressure.

Abstract: A method for controlling a vehicle torque converter lockup clutch during a deceleration coasting event includes producing slip across the clutch by reducing the clutch's torque capacity, decreasing said slip by increasing said torque capacity, and maintaining slip across the clutch.

Abstract: A method of controlling a hydraulic actuator of a friction coupling that includes a pump, which is driven by an electric motor, a pressure line, which contains a non-return valve and which runs from the pump to an actuator cylinder with an actuator piston that acts on the friction coupling. A rapid drain valve has a flow connection to the actuator cylinder and contains a slide that responds to the pressure prevailing on the side of the pump that faces the slide. To optimize the dynamic and static control behavior of the actuator, a control variable is determined for the electric motor from the target pressure and the actual pressure in the actuator cylinder. At least two different control algorithms are executed, depending on whether the difference between the target pressure and the actual pressure is positive or negative.

Abstract: A method controls an amount of time required to commence transmitting torque of an internal combustion engine equipped with a stop/start feature to a transmission configured to transmit the torque of the engine to drive-wheels in a vehicle. The method includes determining whether a start of the engine is likely. The method also includes pre-filling with fluid a hydraulically-actuated clutch that is configured to connect the engine to the transmission when the start of the engine is likely. Accordingly, the amount of time required to commence transmitting torque of the engine to the transmission is reduced. A system employs the method for controlling an amount of time required to commence transmitting torque of the engine.

Abstract: A hydraulic control device includes a first oil path; a second oil path; a third oil path; an engagement pressure generation unit; a signal pressure generation unit; and an internal pressure switching unit that switches between a non-reduced pressure state where locking occurs due to the signal pressure inputted and a source pressure is outputted unchanged as internal pressure to the first oil path, and a reduced pressure state where the signal pressure is not inputted and a hydraulic pressure is regulated to a constant pressure from the source pressure, based on a feedback pressure of the internal pressure and an urging force of a first urging unit, and outputted as the internal pressure to the first oil path.

Abstract: A torque converter having a lockup clutch or a coupling device, for selectively providing a mechanical connection between a drive unit and a drive train. The lockup clutch (C) or coupling device has a driving part connected to the drive unit and a driven part connected to the drive train. The torque converter also has a control system for applying a first pressure in a sense to cause frictional engagement between the driving part and the driven part and a second pressure in a sense to cause disengagement of the driving part and the driven part. A differential between the pressures is progressively controllable by the control system so as to control the relative positioning between the driven part and the driving part.

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 power transfer mechanism control device that controls a power transfer mechanism which is mounted on a vehicle including an automatically stoppable and automatically startable motor and which transfers power from the motor to an axle side via a friction engagement element actuated by a fluid pressure from a fluid pressure actuator, wherein during neutral control performed while the motor is in operation, a neutral control amount, which is a control amount for causing the friction engagement element to stand by in a neutral state with pressure lower than a complete engagement pressure, is set on the basis of a power transfer state of the power transfer mechanism to control the fluid pressure actuator, and learned, and while the motor is automatically stopped, the fluid pressure actuator is controlled using the learned neutral control amount such that the friction engagement element stands by in the neutral state.

Abstract: A method for controlling a vehicle torque converter lockup clutch during a deceleration coasting event includes producing slip across the clutch by reducing the clutch's torque capacity, decreasing said slip by increasing said torque capacity, and maintaining slip across the clutch.

Abstract: A method for controlling torque transmitted between an internal combustion engine and a torque transmission device includes controlling actuation of a torque converter clutch device effective to maintain an engine output within a predetermined range when an input to the transmission is less than a threshold, and controlling actuation of the torque converter clutch device effective to maintain a relative speed across the torque converter substantially at a predetermined magnitude when the input to the transmission is greater than the threshold.

Abstract: A method for engagement of an impeller clutch includes a process for decreasing a back pressure relative to a clutch engagement pressure by decreasing an internal pressure of a torque converter in a case where the impeller clutch is brought into an engaged state, the impeller clutch enabling a driving force of an engine to be transmitted and disconnected to and from a pump impeller of the torque converter, transmission and disconnection of the driving force between the engine and the pump impeller being controlled by the clutch engagement pressure that is applied to the impeller clutch through an independent oil passage.

Abstract: A vehicle control apparatus that controls a vehicle having a torque converter provided on a power transmission path between an internal combustion engine and a transmission is provided. The torque converter includes a pump impeller, to which rotational power from the internal combustion engine is input to rotate, a turbine runner that receives oil from the rotating pump impeller and transmits the rotational power toward the transmission, and an impeller clutch that is configured to connect and disconnect the rotational power transmission from the internal combustion engine to the pump impeller. The vehicle control apparatus controls the internal combustion engine and the impeller clutch, such that, when a throttle opening degree is equal to or larger than a first threshold value during control of the impeller clutch from a non-engaged state to a completely engaged state, lowers an output torque of the internal combustion engine.

Abstract: A vehicle control apparatus that controls a vehicle having a torque converter provided on a power transmission path between an internal combustion engine and a transmission is provided. The torque converter includes a pump impeller, to which rotational power from the internal combustion engine is input to rotate, a turbine runner that receives oil from the rotating pump impeller and transmits the rotational power toward the transmission, and an impeller clutch that is configured to connect and disconnect the rotational power transmission from the internal combustion engine to the pump impeller. The vehicle control apparatus controls the internal combustion engine and the impeller clutch, such that, when a rotation number of the internal combustion engine is equal to or less than a first threshold value during control of the impeller clutch from a non-engaged state to a completely engaged state, increases the rotation number of the internal combustion engine.

Abstract: A drilling machine includes a compressor coupled to a prime mover through a hydraulic clutch, wherein the hydraulic clutch is repeatably moveable between engaged and disengaged conditions. The compressor is allowed to provide air and is restricted from providing air in response to the hydraulic clutch being in the engaged and disengaged conditions, respectively. The hydraulic clutch is moveable between the engaged and disengaged conditions during operation of the prime mover.