This clutch control device is provided with: a first valve; a second valve; a valve control unit configured to control the operation of each of the first valve and the second valve; an operation determination unit configured to perform an operation determination for the clutch device; and an initial operation completion determination unit which determines whether an initial operation of the clutch device has been completed. The valve control unit, if it is determined by the operation determination unit that an on-off switching process is required, subjects both the first valve and the second valve to opening-control. If it is determined by the initial operation completion determination unit that the initial operation has been completed, the valve control unit subjects the second valve to closing-control.

A method controls a hydraulic system for an actuation device and a cooling and/or lubricating device of a motor vehicle. The hydraulic system has a pump, multiple first actuation valves which are each arranged between a system rail connected to a pump outlet and a hydraulic consumer, as well as an additional valve which is arranged between the pump outlet and a coolant and/or lubricant supply line. The pump is switched between a normal operation and an enhanced operation according to an existing total energy demand of the hydraulic consumer. In normal operation, the pump is permanently driven and the additional valve is opened and closed to control pressure in the system rail. In enhanced operation, the pump is permanently driven, the additional valve is permanently closed and each of the actuation valves is operated according to an individual energy demand of the respective hydraulic consumer.

A housing of a solenoid valve unit for controlling a central clutch actuator of a utility vehicle is configured for installation in a transmission housing, preferably in a clutch case, and for accommodating at least one solenoid valve. The housing has an elongate housing shape that is curved along its longitudinal direction to enable installation in tight spaces.

A hydraulic control device with a pressure control valve that has a control piston and a modulating piston which can move relative to one another. The control piston and the modulating piston are pushed apart from one another by at least one spring. At one end face of the modulating piston there is arranged a pressure chamber in such a manner that when the pressure chamber is filled, the modulating piston is caused to move in the direction toward the control piston. The pressure chamber can be filled by a first volume flow Q1 of a pressure medium. A venting line, with at least one further throttle, is connected to the pressure chamber. A second volume flow Q2 can be discharged, via the venting line, from the pressure chamber. The hydraulic control device can be utilized in a marine transmission.

Methods and systems are provided for wet clutch pressure control to reduce drag and degradation of rotary seals in a transmission. In one example, a method may include determining an upper threshold pressure based on a rotational speed of a shaft of the transmission, determining a lower threshold pressure based on the rotational speed of the shaft, and adjusting a pressure of hydraulic fluid applied to the clutch to be between the upper threshold pressure and the lower threshold pressure. In this way, the pressure of the hydraulic fluid applied to the clutch may be maintained at a level that allows full torque transfer by the wet clutch while reducing drag on the rotary seals.

A continuous variable transmission (CVT) hydraulic pressure control device includes: a pressure regulation valve regulating an operation pressure of oil supplied to a friction element of a forward-rearward device; and a switch valve to respectively switch oil discharge paths through which the oil supplied to the friction element is discharged, respectively by a pilot pressure from the pressure regulation valve and an elastic force of a return spring. In particular, the oil discharge paths switched by the switch valve have oil flow resistances different from each other.

A transmission for a machine is disclosed. The transmission may comprise a first torque path for transmission of torque from an input shaft to an output shaft, and a single clutch element along the first torque path. The transmission may further comprise a clutch actuator configured to actuate engagement of the clutch element, and a clutch pressure control (CPC) valve configured to permit a flow of hydraulic fluid to the clutch actuator when in an open position to cause the clutch actuator to actuate engagement of the clutch element. The transmission may further comprise a FMR valve having a failure position obstructing flow of the hydraulic fluid from the CPC valve to the clutch actuator when the CPC valve is in the open position. The FMR valve actuated by pilot pressure from a CPC valve that controls actuation of other clutch elements that are not on the first torque path.

The present disclosure describes a hydraulic control system comprising a first pressure chamber and a second pressure chamber, each pressure chamber configured to receive a hydraulic fluid, a first movable member configured to assume a position depending on a hydraulic pressure of the hydraulic fluid in the first pressure chamber and a second movable member configured to assume a position depending on a hydraulic pressure of the hydraulic fluid in the second pressure chamber, a hydraulic command circuit configured to provide the hydraulic fluid and to control the hydraulic pressure of the hydraulic fluid in the first pressure chamber and/or the second pressure chamber, having a switchable valve in fluid communication with the first pressure chamber, wherein the switchable valve is configured to be pilotable depending on the hydraulic pressure of the hydraulic fluid in the second pressure chamber.

A logic valve for management of a hydraulic actuator comprising: a valve body with a hollow seat which extends along a work direction and communicates with a first port adapted for receiving a pressurized working fluid, a second port adapted for fluidly coupling with an operating chamber of the hydraulic actuator, and a third port adapted for discharging the working fluid; a slider within the hollow seat movable along the work direction; and a spring between the valve body and the slider and oriented to act on the slider along the work direction in the direction away from said third port, wherein the slider is movable between a first operating configuration fluidly coupling the second and third ports and excluding fluid communication between them and the first port, and a second operating configuration fluidly coupling the first and second ports and excluding fluid communication between them and the third port.

A housing of a solenoid valve unit for controlling a central clutch actuator of a utility vehicle is configured for installation in a transmission housing, preferably in a clutch case, and for accommodating at least one solenoid valve. The housing has an elongate housing shape that is curved along its longitudinal direction to enable installation in tight spaces.