A valve device includes a relief valve configured to be opened when a pressure in a fluid pressure circuit reaches a predetermined pressure and to relieve a working fluid, a tank passage connected to a tank, a main relief passage connecting the relief valve and the tank passage, and a sub relief passage branching from the main relief passage and connected to the tank passage separately from the main relief passage.

The disclosure relates to a flight control system comprising at least one hydraulic servo actuator, wherein the servo actuator includes a two-stage electrohydraulic servo valve, wherein the servo valve comprises a pilot stage in which the control current is translated into a hydraulic control pressure, and a power stage in which a valve slide is moved in response to the control pressure in order to adjust the throughflow direction and throughflow cross-section of the valve. The disclosure furthermore relates to an aircraft comprising such a flight control system.

In accordance with at least one aspect of this disclosure, a system includes, a servo configured to control a position of a valve, a driver operatively connected to control movement of the servo, a control module operatively connected to control the driver, can configured to control the driver with pulse width modulated output to control a frequency of a generator through movement of the servo.

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 self-raising assembly is operative to rotate the support structure from the deployed position to the stowed position. The self-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 drop-in lube boost valve assembly replaces an OE lube boost valve assembly in a vehicle transmission hydraulic circuit. The OE valve assembly has a valve body with inlet, balancing and outlet ports. The drop-in valve assembly includes a sleeve having inlet and outlet ports, and a bore extending between and fluidically connecting the ports. The drop-in valve ports are spaced from each other. The sleeve includes valve and spring chambers. A valve has a valve face, a sealing portion and a spring stem and is positioned in the sleeve with the sealing portion positioned in the sleeve bore. A spring is positioned on the spring stem. The valve reciprocates in the sleeve between an open state in which the sealing portion does not overlie the sleeve outlet port and a closed state in which the sealing portion overlies and closes off the outlet port.

An agricultural machine includes a float cylinder interconnecting a header linkage system and a frame. A rod side accumulator is in fluid communication with a rod side fluid port of the float cylinder. A float control valve is selectively controllable between an open position allowing fluid communication between a pressure source and the rod side accumulator, and a closed position blocking fluid communication between the pressure source and the rod side accumulator. A downforce accumulator is in fluid communication with a piston side fluid port of the float cylinder. A downforce control valve controls fluid communication between the pressure source and the downforce accumulator. A downforce return valve controls fluid communication between the downforce accumulator and the tank.

An agricultural machine includes a float cylinder interconnecting a header linkage system and a frame of the machine. A first rod side accumulator and a second rod side accumulator are both in fluid communication with a rod side fluid port of the float cylinder. A first accumulator control valve is positioned to control the first rod side accumulator, and is selectively controllable between an open position allowing fluid communication between the first rod side accumulator and the rod side fluid port of the float cylinder, and closed position blocking fluid communication between the first rod side accumulator and the rod side fluid port of the float cylinder. The system provides a slower first float response with the first accumulator control valve open, and a faster second float response with the first accumulator control valve closed.

A single stage flapper type servovalve comprises a valve housing comprising a bore, a pair of opposed nozzles arranged in the bore and a flapper element arranged between the pair of nozzles. The valve housing further comprises a plurality of fluid ports for communicating a working fluid to and from the nozzles and in fluid communication with the housing bore. The valve housing and the nozzles are both made from a stainless steel material.

A raising assembly for use with a gangway connected for rotation between a raised stowed position and a lowered deployed position. The raising assembly comprises at least one fluid actuated cylinder connected to the gangway. A raising actuator is operative to cause operation of the cylinder in a manner that rotates the gangway toward the stowed position while the raising actuator is continuously activated by an operator. A lowering actuator is operative to cause operation of the cylinder in a manner that rotates the gangway toward the deployed position due to gravitational forces while the lowering actuator is continuously activated by the operator. The raising assembly is configured to maintain the gangway at a current position between the stowed position and the deployed position if the operator does one of ceasing to activate the raising actuator while raising the gangway or ceasing to activate the lowering actuator while lowering the gangway.

The disclosure relates to a flight control system comprising at least one hydraulic servo actuator, wherein the servo actuator includes a two-stage electrohydraulic servo valve, wherein the servo valve comprises a pilot stage in which the control current is translated into a hydraulic control pressure, and a power stage in which a valve slide is moved in response to the control pressure in order to adjust the throughflow direction and throughflow cross-section of the valve. The disclosure furthermore relates to an aircraft comprising such a flight control system.