A pressure-balance valve for balancing the pressures of fluids admitted into the pressure-balance valve via respective second ducts. The pressure-balance valve has both a chamber for guiding movement in translation of a piston, and also fluid flow paths, each comprising a said second duct and a first duct for admitting a fluid coming from the same fluid source as the fluid flowing in its second duct. Each of the first ducts is provided with a shutter co-operating with a ramp arranged on the piston. Movement of the piston in translation as a result of a pressure difference between the fluids respectively admitted into the second ducts causes one of the shutters to slide along the corresponding ramp and consequently allows additional fluid to be delivered from a first duct to the second duct of the same fluid flow path.

A pressure-balance valve for balancing the pressures of fluids admitted into the pressure-balance valve via respective second ducts. The pressure-balance valve has both a chamber for guiding movement in translation of a piston, and also fluid flow paths, each comprising a said second duct and a first duct for admitting a fluid coming from the same fluid source as the fluid flowing in its second duct. Each of the first ducts is provided with a shutter co-operating with a ramp arranged on the piston. Movement of the piston in translation as a result of a pressure difference between the fluids respectively admitted into the second ducts causes one of the shutters to slide along the corresponding ramp and consequently allows additional fluid to be delivered from a first duct to the second duct of the same fluid flow path.

This disclosure includes hydraulic apparatuses and methods for redundant actuation of a hydraulic device. Some apparatuses include a hydraulic device having a first hydraulic actuator and a second hydraulic actuator, wherein each of the first and second hydraulic actuators comprises at least a first hydraulic cavity, a second hydraulic cavity, and a piston. Some apparatuses also include a controller coupled to the hydraulic device. In some embodiments, the controller is configured to receive hydraulic fluid from a fluid source via at least two parallel hydraulic lines coupled to the controller, select a first hydraulic line of the at least two parallel hydraulic lines, and transfer the hydraulic fluid from the selected first hydraulic line to a first cavity of the first hydraulic actuator to apply pressure to a first piston to actuate the hydraulic device.

A fluid system is provided that includes a first actuator, a second actuator and a valve system. The valve system includes a first control valve, a second control valve and a transfer valve. During a first mode of operation, the transfer valve is configured to fluidly couple the first control valve to the first actuator and fluidly couple the second control valve to the second actuator, and the transfer valve is also configured to fluidly decouple the first control valve from the second actuator and fluidly decouple the second control valve from the first actuator. During a second mode of operation, the transfer valve is configured to fluidly couple the first control valve to the first actuator and the second actuator, and the transfer valve is also configured to fluidly decouple the second control valve from the first actuator and the second actuator.

An actuator system having various features is disclosed. An actuator system may have a first and a second electrohydraulic servo valve. A control selector may connect one of the electrohydraulic servo valves to a cylinder and may isolate the other electrohydraulic servo valve to ameliorate leakage in response to a switching solenoid valve operating. In this manner, one electrohydraulic servo valve may be connected to a cylinder to operate the cylinder, and the other electrohydraulic servo valve may be isolated from the cylinder, for example, to provide a standby electrohydraulic servo valve.

An actuator system having various features is disclosed. An actuator system may have a first and a second electrohydraulic servo valve. A control selector may connect one of the electrohydraulic servo valves to a cylinder and may isolate the other electrohydraulic servo valve to ameliorate leakage in response to a switching solenoid valve operating. In this manner, one electrohydraulic servo valve may be connected to a cylinder to operate the cylinder, and the other electrohydraulic servo valve may be isolated from the cylinder, for example, to provide a standby electrohydraulic servo valve.

A thermal management system includes a first hydraulic system for circulating a first hydraulic fluid at a first temperature and a second hydraulic system for circulating a second hydraulic fluid at a second temperature that is higher than the first temperature. The thermal management system also includes a sealed heat transfer device coupled between the first hydraulic system and the second hydraulic system. The sealed heat transfer device is not in flow communication with either of the first hydraulic system and the second hydraulic system. The sealed heat transfer device is configured to transfer heat from the second hydraulic fluid to the first hydraulic fluid.

A thermal management system includes a first hydraulic system for circulating a first hydraulic fluid at a first temperature and a second hydraulic system for circulating a second hydraulic fluid at a second temperature that is higher than the first temperature. The thermal management system also includes a sealed heat transfer device coupled between the first hydraulic system and the second hydraulic system. The sealed heat transfer device is not in flow communication with either of the first hydraulic system and the second hydraulic system. The sealed heat transfer device is configured to transfer heat from the second hydraulic fluid to the first hydraulic fluid.

A rotary actuator includes a housing defining a first arcuate chamber comprising a cavity, a fluid port in fluid communication with the cavity, and an open end. A rotor assembly in the housing includes an output shaft and a rotor arm extending radially outward from the output shaft. An arcuate-shaped piston is disposed in the housing for movement in the arcuate chamber. The rotary actuator includes a fluid line is coupled to the fluid port, a high pressure fluid line, a low pressure fluid line, and a central pressure source coupled to the high pressure fluid line. A servo valve is positioned between the central pressure source and the hydraulic actuator and is controllable to selectively connect the fluid line to the high pressure fluid line and the low pressure fluid line to control movement of the hydraulic actuator.

A hydraulic cylinder system 1 is provided with a plurality of cylinders 3a and 3b, valves 4a and 4b provided at each of the cylinders 3a and 3b for adjusting amounts of operating fluid into and out of the cylinders 3a and 3b, driving systems 5a and 5b having motors 6a and 6b provided at each of the valves 4a and 4b for driving the valves 4a and 4b, and a connecting member 8 for connecting the motors 6a and 6b of the driving systems 5a and 5b in a manner capable of interlocking with each other.