A hydraulic control system for a transmission is provided with a power source, two drive wheels, a power transmission device, a hydraulic pump, a main valve, and a controller. The power transmission device is configured to be set to a plurality of speed stages. The main valve is disposed between the hydraulic pump and the power transmission device and adjusts the main pressure of hydraulic fluid supplied from the hydraulic pump to the power transmission device. The controller controls the main valve. The controller sets the main pressure to a pressure value derived by correcting a clutch holding pressure of the set speed stage based on a load applied to each of the drive wheels.

Systems and methods for operating a transmission of a hybrid vehicle's driveline are presented. In one example, the systems and methods adjust operation of an electrically driven transmission pump that supplies transmission fluid to one or more transmission components in response to a rotational stopping position of a mechanically drive transmission pump.

A working machine includes a traveling device to change a traveling speed in accordance with a flow rate of an operation fluid, a traveling operation device to change the flow rate of the operation fluid to be supplied to the traveling device, and a switching operation portion to change, at multiple steps, a supply amount of the operation fluid to be supplied to the traveling device, the supply amount corresponding to an operation extent of the traveling operation device.

A work vehicle includes an engine, a drive wheel, a power transmission mechanism configured to transmit a driving power of the engine to the drive wheel, and a control unit configured to control the power transmission mechanism. The power transmission mechanism has a torque converter including a first clutch, and a second clutch coupled to the torque converter. The control unit controls an oil pressure supplied to the first clutch to a predetermined oil pressure when the second clutch is partially engaged.

Because an EOP starts operating from when a decrease in discharge flow rate of an MOP is predicted or detected, a PL actual pressure that should be obtained with a PL command pressure set to a value for a required transmission torque is more easily maintained even when the discharge flow rate of the MOP becomes insufficient. After a lapse of a predetermined period of time from the start of operation of the EOP, the PL command pressure is temporarily set to a value higher than the value for the required transmission torque, and a regulator valve is controlled to operate to close a drain port. Therefore, the operation of the EOP in a high PL actual pressure is reduced, and a delay in response of a pressure regulating operation of the regulator valve in the process of reduction of the discharge flow rate of the MOP is reduced.

A one-way valve includes: a cylindrical section, one end of which is inserted into and fixed to an inside of a pipe, the cylindrical section including a through-hole through which oil is passed in an axial direction; and a columnar section housed inside the pipe and including, in another end thereof, a plurality of lateral holes through which oil is passed, flow of oil being blocked when the other end is inserted into a one-side opening section of the cylindrical section.

A power train device for a vehicle is provided with a selector valve that is switched between a first state in which oil discharged from an electric oil pump is able to be supplied as a hydraulic fluid to an engagement hydraulic chamber of a vehicle-starting frictional engagement element, and a second state in which the oil is able to be supplied as a lubricating oil to the vehicle-starting frictional engagement element through a first lubricating oil supply circuit, depending on a magnitude of a discharge pressure of a mechanical oil pump.

A work vehicle includes an engine, a drive wheel, a power transmission mechanism configured to transmit a driving power of the engine to the drive wheel, and a control unit configured to control the power transmission mechanism. The power transmission mechanism has a torque converter including a first clutch, and a second clutch coupled to the torque converter. The control unit controls an oil pressure supplied to the first clutch to a predetermined oil pressure when the second clutch is partially engaged.

A hydraulic control unit of a vehicle drive system including an automatic transmission, and an oil pump device, includes: a first electromagnetic valve; a second electromagnetic valve; first and second oil passages; a third oil passage; a manual valve operated to connect and disconnect the first and third oil passages and a drain oil passage to and from each other, in response to an operation of a manually operated shifting device by a vehicle operator, such that the first oil passage is connected to the third oil passage when the shifting device is placed in a first operating position, while the first oil passage is connected to the drain oil passage when the shifting device is placed in a second operating position; an accumulator connected to the first oil passage; and a check valve provided in the second oil passage.

Because an EOP starts operating from when a decrease in discharge flow rate of an MOP is predicted or detected, a PL actual pressure that should be obtained with a PL command pressure set to a value for a required transmission torque is more easily maintained even when the discharge flow rate of the MOP becomes insufficient. After a lapse of a predetermined period of time from the start of operation of the EOP, the PL command pressure is temporarily set to a value higher than the value for the required transmission torque, and a regulator valve is controlled to operate to close a drain port. Therefore, the operation of the EOP in a high PL actual pressure is reduced, and a delay in response of a pressure regulating operation of the regulator valve in the process of reduction of the discharge flow rate of the MOP is reduced.