The invention relates to a towing vehicle (100) for manoeuvring aeroplanes without using tow bars, the towing vehicle (100) comprising a coupling device (122/124) for gripping and lifting the nose wheel of the aeroplane to be manoeuvred. According to the invention, the towing vehicle (100) comprises a pressure store (176), in which operating fluid is stored under pressure, a release initiation device (178), which can be actuated manually by an operator and which in a release initiation position connects the pressure store (176) to a release device (180), and the release device (180), which is configured and intended, upon manual transfer of the release initiation means (178) into the release initiation position by the operator, initially to lower the nose wheel of the aeroplane automatically until it stands on the travel surface, simply by means of the pressure energy stored in the pressure store (176) and the potential energy of the nose wheel load, and only subsequently to release the nose wheel.

A system and method configured to direct the braking energy from a high-pressure port at the motor side of a hydraulic circuit to emergency steering, braking, accumulator(s) charging, and/or various work functions. The system and method are also configured to return hydraulic fluid back to the same high-pressure port when the motor is running as a pump.

This disclosure includes systems and methods for actuating hydraulically-actuated devices.

A hydraulic system for an aircraft. The hydraulic system can include a hydraulic actuator that is operatively coupled to a flight control member. Hydraulic fluid is moved through the hydraulic system by an engine driven pump that delivers hydraulic fluid to the actuator at a first pressure, and a boost pump that delivers hydraulic fluid to the actuator at a second pressure that is higher than the first pressure. The hydraulic system is configured such that the hydraulic fluid returning from the actuator to the engine driven pump can be delivered to the boost pump prior to reaching the engine driven pump.

A system and method for providing redundancy in hydraulic circuits in multi-cycle hydraulic tools is described. The problems of dysfunctional hydraulic tool due to the failure of electromechanical actuators are addressed by providing redundant actuators and associated circuitry design.

A transmission hydraulic control system for an automobile transmission includes a hydraulic circuit in fluid communication with the at least one torque transmitting device, a transmission pump in fluid communication with the hydraulic circuit and adapted to provide pressurized hydraulic fluid to the hydraulic circuit, an accumulator in fluid communication with the hydraulic circuit and having an annular cylindrical shape concentric with a center-line of the automatic transmission, an annular piston moveable between a first position and a second position, and a spring adapted to bias the piston to the first position, and a valve mechanism positioned between the hydraulic circuit and the accumulator, the valve mechanism adapted to selectively allow fluid communication between the accumulator and the hydraulic circuit.

An apparatus for controlling a hydraulic machine, for example a turbine, pump or pump turbine, using variable-speed driven fixed displacement pumps. The apparatus includes a device for carrying out an emergency shut-off that is characterized by low energy consumption and high efficiency while guaranteeing all the operation-relevant and safety-relevant requirements of a hydraulic machine.

A bootstrap hydraulic reservoir includes a bootstrap chamber to hold hydraulic fluid, a piston chamber fluidly connected to a pressure line of the hydraulic fluid system, a piston having a bootstrap end portion held within the bootstrap chamber and a pressure end portion held within the piston chamber, and a hydraulic accumulator fluidly connected to the pressure line of the hydraulic fluid system. The hydraulic accumulator accumulates pressurized hydraulic fluid from the pressure line. The bootstrap hydraulic reservoir also includes a valve fluidly connected to the pressure line of the hydraulic fluid system between the hydraulic accumulator and an outlet of a pump of the hydraulic fluid system. The valve includes an actuator selectively moves the valve to an open position when the pressure line of the hydraulic fluid system is de-pressurized.

An electric motor-driven, rolling element screw linear actuator is presented which work in cooperation with an hydraulic actuator and share several components. This is achieved through the integration of a screw-driven integrated nut piston assembly. Combining the use of an electric screw driven actuator can also reduce the need for a redundant hydraulic system, resulting in the elimination of 50% of connections, valves, piping, pumps, filters etc., while still being 100% redundant. An additional advantage is that the two drive systems are technologically independent, and therefore will not both fail because of an identical component flaw or failure point. The systems may also be used at the same time if conditions require force in excess of that generated by the hydraulic actuator alone.

An electric-powered fail-safe actuator for use with a valve, where the actuator stores potential energy for conversion to kinetic energy to close or open the valve to the fail-safe position.