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 method actuates a hydraulic system for an actuation device of a motor vehicle. The hydraulic system has a pump and multiple valves which are each arranged between a system rail connected to a pump outlet and a hydraulic consumer. The pump is switched between a normal operation and an enhanced operation according to an existing total energy demand of the hydraulic consumers. In normal operation, the pump is driven when the system pressure is below a lower pressure threshold and switched off when the system pressure is above an upper pressure threshold. In the enhanced operation, the pump is permanently driven and each of the valves is operated according to an individual energy demand of the respective hydraulic consumer as soon as the system pressure achieves or exceeds a threshold value.

A shaft (W) for a motor vehicle transmission (G) may have axial bore holes positioned within the shaft and configured to guide fluid within the shaft. The shaft may have first, second, and third axial sections (W1, W2, W3), the second axial section being axially between the first and third axial sections. Fluid enters the axial bore holes in the second axial section and exits the axial bore holes in the first and third axial sections. One of the axial bore holes (B2; B1, B1a) is arranged, at least partially, in the first axial section and is radially spaced from an axis of rotation (WA) of the shaft. Another of the axial bore holes (B1RS; B_SE5, B3a) is arranged, at least partially, in the third axial section. The one of the axial bore holes (B2; B1, B1a) is coaxial with the other of the axial bore holes (B1RS; B_SE5, B3a).

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 drive force transfer device includes a multi-plate clutch that transfers a drive force using a friction force generated between a plurality of clutch plates; a housing that houses the multi-plate clutch; a piston that presses the multi-plate clutch using a hydraulic pressure of operating oil supplied to a hydraulic chamber provided in the housing; a hydraulic unit configured to supply the operating oil to the hydraulic chamber; and a control device configured to control the hydraulic unit, the control device being configured to correct a control amount for the hydraulic unit based on a result of a temperature estimation based on operation of the hydraulic unit.

An automatic transmission includes a clutch having a drum section, a hub, a friction plate, a piston that presses the friction plate, a hydraulic chamber to which hydraulic oil is supplied to urge the piston in a direction toward the friction plate, and a cancellation chamber to which hydraulic oil is supplied to cancel a centrifugal hydraulic pressure applied to the hydraulic oil in the hydraulic chamber, and the piston is interposed between the hydraulic chamber and the cancellation chamber. The drum section includes communication passages that extend in a radial direction and respectively communicate with the hydraulic chamber and the cancellation chamber. Of the communication passages, in the communication passage that communicates with the cancellation chamber, an adjustment member is provided at an end portion on a radially inner side, and can adjust an atmospheric air release position of the communication passage in the radial direction.

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 hydraulic clutch assembly can include a shaft defining a shaft channel, one or more hydraulic ports defined through the shaft, and one or more lubrication holes defined through the shaft. A porting manifold can be disposed at least partially within the shaft channel. The porting manifold can include a control pressure path in fluid communication with the one or more hydraulic ports and a lubrication flow path in fluid communication with the one or more lubrication holes. The control pressure path and the lubrication path can be fluidly isolated in the porting manifold.

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.