A fan drive device for use with a hydraulic pump featuring a constant displacement volume is disclosed. The fan drive device includes a hydraulic motor configured to be directly coupled to a fan. The hydraulic motor includes a first working connection, a second working connection, and a constant displacement volume. The fan drive device further includes a hydraulic valve having a pump connection and a tank connection. The hydraulic valve includes two fluid connections, each of which can be fluidically connected to the hydraulic motor. The hydraulic valve is designed as a proportional valve including a continuously adjustable control piston proportional to a control current of the hydraulic valve as the sole control mechanism for controlling the fan speed.

A series hydraulic hybrid system for a vehicle is described. The system has a hydraulic circuit, a hydraulic working assembly, and a hydraulic accumulator assembly. The hydraulic circuit has a first hydraulic displacement unit in fluid communication with a second hydraulic displacement unit. The first hydraulic displacement unit is drivingly engaged with a power source. The hydraulic working assembly has a hydraulic implement and a hydraulic working pump in fluid communication with the hydraulic implement, the hydraulic working pump drivingly engaged with the power source. The hydraulic accumulator assembly has a high pressure hydraulic accumulator and a low pressure hydraulic accumulator. The hydraulic accumulator assembly selectively fluidly connects to the hydraulic circuit and the hydraulic accumulator assembly selectively fluidly connects to the hydraulic working assembly.

A pump system includes an actuator which can be retracted by a fluid in the pump system. Also included is a pump with a first drive coupling and a rotational power device with a second drive coupling. The second drive coupling is configured to removably mate with the first drive coupling for powering the pump. A spool valve that is spring loaded and in fluid connection with the pump when the spool valve is in a stow position is also included. In addition, the pump system includes both a relief valve and a reservoir both in fluid connection with the actuator.

A hydraulic control system for a machine is provided. The hydraulic control system includes a fluid reservoir and a pump motor. The pump motor is fluidly coupled to the fluid reservoir. The pump motor is configured to provide pressurized fluid and to receive fluid to provide a power output to the shaft. The hydraulic control system further includes an actuator and an accumulator fluidly coupled to the pump motor and the actuator. The hydraulic control system further includes an accumulator valve and a controller. The accumulator valve is fluidly coupled between the accumulator and the pump motor. The controller is in communication with the pump motor and the accumulator valve. The controller is configured to detect an operator command to operate the power source; determine pressure at the accumulator; and selectively move the accumulator valve to fluidly connect the accumulator with the pump motor.

A redundant accumulator system for delivery of pressurized hydraulic fluid to blowout preventers (BOPs) and other well equipment during coiled tubing and wirelining operations that has sufficient reserve fluid capacity to simultaneously operate a plurality of BOPs and other well equipment and to hold a plurality of BOPs closed in the event of a hydraulic fluid leak, and is appropriately sized for use aboard an offshore vessel or platform or for use in close proximity to an inland wellhead. The accumulator system includes a hydraulic fluid capacity that is at least twice the capacity of the accumulators, a plurality of pneumatically operated pumps in parallel, each having the maximum inlets and outlets for their size to maximize the charging capacity of the accumulator system and allow the system to be charged to operational pressure in less than thirty minutes.

In a hydraulic driving system for construction machines, when track motors 3f and 3g are operated and the delivery pressure of a main pump 2 increases to a second value PS2 of the set pressure of a main relief valve 14, the set pressure of a signal pressure relief valve 16 increases from a third value PA1 to a fourth value PA2, which is smaller than the second value PS2 of the set pressure of the main relief valve 14, the difference between the second value PS2 and the fourth value PA2 being smaller than the target LS differential pressure. With such a structure, even if one of actuators reaches the stroke end and the delivery pressure of the hydraulic pump rises to the set pressure of the main relief valve, the other actuators do not stop, and further when the main relief valve is configured to increase the set pressure during operation of a specific actuator, the load pressure of the specific actuator does not increase to the increased set pressure of the main relief valve.

A hydraulic system that has a hydraulic pump connected to and in communication with a hydraulic motor, at least one hydraulic cylinder, or both by a first conduit and a second conduit (i.e., a high side and a low side). The hydraulic system has a bypass valve connected to and in communication with the first conduit and the second conduit. The bypass valve has a preset pressure that is above a minimum low side pressure. When a shock load occurs in the hydraulic system and a related drop in pressure on the low side occurs, the bypass valve opens when the preset pressure is passed thereby preventing the pressure from dropping to the minimum low side pressure. The hydraulic system thereby avoids a low loop event that could cause damage to the hydraulic system without the presence of larger charge pumps or accumulators.

A hydraulic system for an aircraft having an engine and an auxiliary power unit includes a first hydraulic subsystem including a first hydraulic pump and a first set of hydraulic-powered components in fluid communication with the first hydraulic pump. The first hydraulic pump is powered by the engine to pump shared hydraulic fluid to the first set of hydraulic-powered components. The hydraulic system includes a second hydraulic subsystem including a second hydraulic pump and a second set of hydraulic-powered components in fluid communication with the second hydraulic pump. The second hydraulic pump is powered by the auxiliary power unit to pump the shared hydraulic fluid to the second set of hydraulic-powered components. A shared return line subsystem and reservoir is in fluid communication with the first and second hydraulic subsystems to return the shared hydraulic fluid to the first and second hydraulic pumps.

A gangway comprises a fixed platform and a support structure connected to the fixed platform in a manner that allows the support structure to rotate with respect to the fixed platform between a raised stowed position and a lowered deployed position. A raising assembly is operative to rotate the support structure from the deployed position to the stowed position. The raising assembly includes at least one fluid actuated cylinder connected between the fixed platform and a distal end of the support structure. A raising actuator is usable by an operator to cause operation of the cylinder in a manner that rotates the support structure toward the stowed position.

A wellhead pressure reduction and power generating assembly includes a wellhead, a supply pipe, a prime mover, a pump, and an accumulator bank. The wellhead is configured to supply a pressurized production fluid flow and is in fluid communication with the supply pipe. The prime mover is configured to induce a pressure drop within the pressurized production fluid flow and is in fluid communication with the supply pipe. The pump is configured to receive a mechanical force of the prime mover and operatively coupled with the prime mover. The accumulator bank is configured to accumulate a pressurized hydraulic fluid and is in fluid communication with the pump.