A servo valve is provided with a first elastic portion, a second elastic portion, and a connecting portion. The first elastic portion extends in an X direction inside a valve body and has a first elastic force exerted on a movable element toward an X2 direction. The second elastic portion extends in the X direction inside the valve body and has a second elastic force exerted on the movable element toward an X1 direction.

The connecting portion is connected to the first elastic portion and the second elastic portion inside the valve body, and is in abutment against a step portion of the valve body and a spool of the movable element at a neutral position of the movable element.

In a load sensing hydraulic control circuit, a pressure compensator elaborates both a load sensing pressure signal to control a pump unit and a pressure compensated power flow for actuators, the power flow being either split or alternatively directed to at least a first and a second actuator control valves so that a differential pressure across the first and second control valves is controlled by the pressure compensator. In one embodiment, the circuit is onboard a construction vehicle to power actuators such is travel left, travel right, swing, boom, arm, bucket and the like.

Exemplary control valves that may be configured as a load sense, closed-center, and/or open-center valve. The control valve may include optional individual valve force sensing to potentially allow an operator to smoothly operate devices operating on low-load work ports even when a variable displacement pump is inducing pressure to operate a device connected to a high-load work port of a separate valve or worksection in the same stack. This optional force sensing may be employed on any or all worksections associated with any valve stack, and may further be included on one or both workports for any given worksection. Each worksection may include parallel and variable paths of fluid supplied by the pump. Also, flow priority to one or more worksections or external valves in a corresponding hydraulic system is optional and can be customized using the variable flow path and a corresponding fixed restriction.

A control valve unit includes a pilot-operated first operation valve 21 that can be operated to a first closed position at which a first oil passage 41 and a tank port 24 are disconnected from each other and a first open position at which the first oil passage 41 and the tank port 24 are connected to each other; and a pilot-operated second operation valve 22 that can be operated to a second closed position at which a second oil passage 42 and the tank port 24 are disconnected from each other and a second open position at which the second oil passage 42 and the tank port 24 are connected to each other.

A shuttle valve includes: a first valve body; a second valve body, a first control-pressure-charged surface and a second control-pressure-charged surface of the first valve body being larger than a third control-pressure-charged surface and a fourth control-pressure-charged surface of the second valve body, a first control pressure from a first inlet pressure port being applied to a first valve body first side, the first control pressure from a second inlet pressure port being applied to a first valve body second side, a second control pressure from a third inlet pressure port being applied to a second valve body first side, the second control pressure from a fourth inlet pressure port being applied to a second valve body second side, a first control pressure acting on a first control-pressure-charged surface and a second control-pressure-charged surface, and the second control pressure acting on a third control-pressure-charged surface and a fourth control-pressure-charged surface.