A control apparatus for a linear solenoid valve configured to regulate a hydraulic pressure in a vehicle transmission. The control apparatus includes a hydraulic control portion configured to output a control command signal that is applied to a solenoid of the linear solenoid valve. The hydraulic control portion outputs, as the control command signal, a regulating control command signal by which the hydraulic pressure is to be regulated to a regulated pressure value that is dependent on a vehicle driving state. When the regulated pressure value is in a certain pressure range in which vibration-based noise is likely to be generated by vibration of the linear solenoid valve that is operated with the regulating control command signal being applied to the solenoid, the hydraulic control portion outputs, as the control command signal, a noise-restraining command signal by which generation of the vibration-based noise is restrained.

A control apparatus for a linear solenoid valve configured to regulate a hydraulic pressure in a vehicle transmission. The control apparatus includes a hydraulic control portion configured to output a control command signal that is applied to a solenoid of the linear solenoid valve. The hydraulic control portion outputs, as the control command signal, a regulating control command signal by which the hydraulic pressure is to be regulated to a regulated pressure value that is dependent on a vehicle driving state. When the regulated pressure value is in a certain pressure range in which vibration-based noise is likely to be generated by vibration of the linear solenoid valve that is operated with the regulating control command signal being applied to the solenoid, the hydraulic control portion outputs, as the control command signal, a noise-restraining command signal by which generation of the vibration-based noise is restrained.

A hydraulic transaxle of the present invention includes an axle, a hydraulic static transmission (“HST”), a center case that has pair of oil passages for circulating the hydraulic oil between the hydraulic pump and the hydraulic motor, and a gear mechanism that transmits an output of the HST to the axle. A case supports the axle and accommodates the HST while also forming an oil reservoir. A hydraulic motor of the HST includes a motor shaft, a cylinder block with a plurality of cylinders fixed to the motor shaft, a plurality of pistons inserted into the cylinders, a fixed swash plate abutted by the plurality of pistons, and a fixed swash plate holder that supports the fixed swash plate with respect to the case. The motor shaft of the hydraulic motor is supported by the center case and the fixed swash plate holder.

An example includes a hydraulically controllable coupling to couple a rotating input and to an output to rotate, or to decouple the input and the output, with coupling and decoupling modes selected by switching a hydraulic device such as a vane pump between a pumping mode and a mode in which it does not pump. In an example, the system cooperates with a transmission to increase the number of possible gear ratios in some examples.

An example includes a hydraulically controllable coupling to couple a rotating input and to an output to rotate, or to decouple the input and the output, with coupling and decoupling modes selected by switching a hydraulic device such as a vane pump between a pumping mode and a mode in which it does not pump. In an example, the system cooperates with a transmission to increase the number of possible gear ratios in some examples.

A hydraulic system for a work machine includes a travel hydraulic device which changes a travel speed in accordance with switching positions of a hydraulic switch valve. A controller controls a proportional valve so as to change a pressure of an operation fluid at an increasing rate over a time while the hydraulic switch valve is switched from a first switching position to a second switching position to increase the travel speed from a first speed to a second speed, and at a decreasing rate over the time while the hydraulic switch valve is switched from the second switching position to the first switching position to decrease the travel speed from the second speed to the first speed. A magnitude of the increasing rate is different from one of the decreasing rate to output an operation fluid.

A hydraulic system includes: a travel motor; travel pump connected to the travel motor, the travel pump driven by an engine; a work pump that sucks hydraulic oil from a tank through a suction line, and supplies the oil to a work hydraulic actuator through a delivery line, the work pump driven by the engine; a switching valve connected to the delivery line, and connected to a part of the suction line downstream of the check valve; and an accumulator connected to the switching valve. The switching valve switches between a neutral position in which the switching valve blocks a pressure accumulation line, a pressure release line, and the relay line, the pressure accumulation position in which the switching valve wherein the pressure accumulation line communicates with the relay line, a pressure release position in which the switching valve brings the relay line into communication with the pressure release line.

A hydraulic system includes: a travel motor; travel pump connected to the travel motor, the travel pump driven by an engine; a work pump that sucks hydraulic oil from a tank through a suction line, and supplies the oil to a work hydraulic actuator through a delivery line, the work pump driven by the engine; a switching valve connected to the delivery line, and connected to a part of the suction line downstream of the check valve; and an accumulator connected to the switching valve. The switching valve switches between a neutral position in which the switching valve blocks a pressure accumulation line, a pressure release line, and the relay line, the pressure accumulation position in which the switching valve wherein the pressure accumulation line communicates with the relay line, a pressure release position in which the switching valve brings the relay line into communication with the pressure release line.

A hydrostatic assembly includes a pressure medium with a variable viscosity and a control device through which at least one process variable or state variable of the hydrostatic assembly is open-loop or closed-loop controlled as a function of the viscosity. The hydrostatic assembly further includes a temperature sensing device configured to sense a temperature of the pressure medium.

A hydrostatic assembly includes a pressure medium with a variable viscosity and a control device through which at least one process variable or state variable of the hydrostatic assembly is open-loop or closed-loop controlled as a function of the viscosity. The hydrostatic assembly further includes a temperature sensing device configured to sense a temperature of the pressure medium.