A hydraulic system for a vehicle transmission with at least two friction elements, the system comprising a first hydraulic circuit comprising a pump for supplying hydraulic fluid to the first hydraulic circuit. A flow restriction may be provided in the first hydraulic circuit between an output of the pump and a sump for providing leakage of hydraulic fluid into the sump. Further, a second hydraulic circuit comprising a second pump may be arranged, wherein the hydraulic pressure in the first circuit is higher compared to the second circuit. A flow control element operated using hydraulic pressure from the first circuit may be arranged for controlling flow/pressure in the second circuit. Further, the hydraulic system may be arranged for generating a line pressure, wherein an actuator for engaging a park lock system may be connected to the first hydraulic circuit for enabling direct actuation by means of the line pressure.

An off-highway recreational vehicle includes side-by-side passenger and driver seats held within a chassis. The seats sit low in the chassis and are covered by a roll-over protection system (ROPS). The vehicle is powered by an engine rearward of the seats that utilizes a continuously variable transmission (CVT) to provide power to the ground engaging members, wherein the CVT is cooled via air captured by a CVT intake body located adjacent the driver-side seat, between the frame and external panels of the utility vehicle.

A hydraulic assembly with a lubricant output, a control output and a pump which can supply a hydraulic fluid flow to the lubricant output and the control output. A switching valve with structurally predefined hysteresis is arranged between a pump output and the control output of the hydraulic assembly. Depending on the pressure in the branch between the pump output and the control output, the valve can be switched between an open position in which the control output is connected to the pump output, and a blocking position in which the control output is blocked off. The switching valve switches from the open position to the blocking position when the pressure provided by the pump exceeds an upper switching threshold, and returns from the blocking position to the open position when the pressure provided by the pump falls below a lower switching threshold. A clutch can be switched by means of such a hydraulic assembly, and a method for actuating the clutch.

A hydraulic actuator can be provided for actuating a functional part by a movement of a force transmission element, with a working piston which can be acted upon by a hydraulic pressure of a pressure supply and is movable thereover between a first extreme position and a second extreme position in a piston/cylinder unit, wherein two chambers separated from one another by the working piston are present and a first chamber is formed as a first working chamber with a pressure inlet and a hydraulic pressure applied to the first pressure inlet urges the working piston in the direction of the first extreme position in order to enlarge the first working chamber. At least one retaining means is provided which is capable of automatically locking the working piston in one of the extreme positions when this extreme position is reached, even without any hydraulic pressure being applied.

A hydraulic arrangement for a vehicle transmission includes a hydraulic pump for providing a system pressure for a first hydraulic system circuit and a lubrication pressure for a second hydraulic lubrication circuit. The arrangement also includes a control valve connected between a pump outlet of the pump and the two hydraulic circuits and has two different switching positions. The control valve, depending on the switching position, acts as a hydraulic connection between the pump and the system circuit or between the pump and the lubrication circuit.

A continuously variable transmission changes a gear ratio by changing a groove width between the fixed side pulley half body and the movable side pulley half body in each of the driving pulley and the driven pulley using pulley pressure. At least any of a drive shaft of the driving pulley and a driven shaft of the driven pulley includes a pulley pressure supply oil passage for supplying pulley pressure to the movable side pulley half body, a lubricating oil passage provided on a downstream of the pulley pressure supply oil passage to supply oil as a lubricating oil to an endless member, and a flow control valve that is provided between the pulley pressure supply oil passage and the lubricating oil passage and operates according to pulley pressure.

A vehicle hydraulic control system comprises a high-low pressure decoupling valve, a high-pressure control oil circuit including a main pressure regulating pilot solenoid valve connected to a transmission controller and used for regulating the main oil pressure according to the instructions of the transmission controller and a main pressure regulating mechanical valve, a low-pressure cooling and lubricating oil circuit, a mechanical pump communication with the high-pressure control oil circuit, and an electronic pump is in communication with the high-pressure control oil circuit or the low-pressure cooling and lubricating oil circuit by means of the high-low pressure decoupling valve. The main pressure regulating mechanical valve is used for guiding the flow output by the electronic pump and/or the mechanical pump in communication with the high-pressure control oil circuit to the low-pressure cooling and lubricating oil circuit according to the control of the main pressure regulating pilot solenoid valve.

A hydraulic circuit for the transmissions of industrial and agricultural vehicles. The circuit comprises a feed pump driven by an internal combustion engine; a lubricating circuit; a main pressure regulator capable of bringing about a first change in the pressure of the working fluid in the circuit, this change in pressure being capable of regulation in relation to a first regulation pressure; a maximum pressure regulator for the lubrication circuit capable of bringing about a second change in pressure of the working fluid depending upon a second regulating pressure; and means for regulating regulation of the first and second regulating pressures.

A thermostatic bypass valve functions to regulate fluid temperature and also to act as a pressure relief valve using a single valve bore. The poppet valve includes a cylinder with a chamber that is thermally immersed in a source passageway such that the valve state is determined by the temperature of the fluid flowing through the source passageway as opposed to the fluid flowing through a return passageway. When the fluid in the source passageway is hot, a poppet is forced against the return passageway side of a valve seat. The poppet may either be rigidly attached to the cylinder or may slide with respect to the cylinder and be forced against the valve seat by a spring. A piston may either be rigidly attached to the housing or may be forced toward the valve seat by a spring.

A continuously variable transmission is provided with a drive belt (6) drive belt (3), fitted between a primary pulley (1) and a secondary pulley (2) of the transmission, each pulley having two pulley sheaves (4, 5) of which at least one pulley sheave (4) in each case is axially movable under the influence of a hydraulic pressure exerted in a pressure cylinder (11; 12) of a respective pulley (1; 2), and with a hydraulic control system for controlling these respective cylinder pressures (Pp, Ps) including two oil pumps (41, 42). A pump flow control valve (100, 48) is provided and is arranged to connect to or disconnect from the main hydraulic line (46) the one oil pump (42) in dependency on a difference between an actual line pressure (Ps) in the main hydraulic line (46) and a desired pressure level there for.