A device for holding a hydraulic cylinder stem in position includes a hydraulic block having series-connected primary and secondary check valves. The latter includes a secondary control stem having a secondary valve body and a seal. A first throttle upstream and a second throttle downstream are closed in a secondary control stem closed position where the seal tightly blocks the secondary check valve, each throttle having a tiny throttle closing gap, preferably 0.1 mm or less. The control stem can move axially into an intermediate position where the throttles remain closed, that is, have a tiny closing gap, but valve body and seal are lifted from a secondary valve seat. The control stem can be moved further into an opening position where the throttles are open, each having an opening gap much larger than the closing gap, and the valve body and seal are lifted from the valve seat.

The subject matter of this specification can be embodied in, among other things, an electrohydraulic positioning control system that includes a shuttle valve configured to direct fluid flow between a selectable one of a first fluid port and a second fluid port, and a fluid outlet configured to be fluidically connected to a fluid actuator, a first servo valve controllable to selectably permit and block flow between the first fluid port, a fluid source, and a fluid drain, a second servo valve controllable to selectably permit and block flow between the second fluid port, the fluid source, and the fluid drain, a first servo controller configured to provide a first health signal and control the first servo valve based on a second health signal, and a second servo controller configured to provide the second health signal and control the second servo valve based on the first health signal.

A hydraulic block for redundancy of an electronic braking device may include: a block body having a motor mounting part to which a motor is coupled and a controller mounting part to which an ECU is coupled; hydraulic control ports formed on the block body, and connected to a first output line of a main braking device and a first hydraulic braking line, in order to perform hydraulic braking on ones of front wheels and rear wheels; drain ports formed on the block body, and connected to a second output line of the main braking device and a second hydraulic braking line, in order to reduce the pressure of the others; and a hydraulic circuit configured to form a flow path of operating fluid in the block body, and control the flow rates and pressures of operating fluids passing through the hydraulic control ports and the drain ports.

An example valve includes: (i) a valve body comprising a supply port and an operating port; (ii) a sleeve comprising a first opening fluidly coupled to the supply port, a second opening fluidly coupled to the operating port, and a seat; (in) a spool configured to move axially within the sleeve, wherein the spool is configured to he seated on the seat of the sleeve when the valve is unactuated, and wherein when the valve is actuated, the spool moves such that a gap is formed at the seat; and (iv) a flow restriction disposed downstream of the gap, wherein when the valve is actuated, fluid is allowed to flow from the supply port through the first opening and the gap and through die flow′ restriction prior to flowing through the second opening to the operating port, such that the flow restriction generates an increased pressure level at the gap.

A hydraulic circuit includes a pump connected to a tank for supplying hydraulic liquid under pressure to a component via a directional control slide valve provided with a feed port connected to an inlet of the component and with a return port connected to an outlet of the component. The hydraulic circuit further includes a pressure limiter connected to the inlet of the component and the tank, and a feed control system for the hydraulic component including a pressure sensor installed upstream of the hydraulic component downstream of the feed port for supplying information about the pressure of the hydraulic liquid and a setpoint pressure. The feed control system further including an actuator for controlling the movement of the directional control slide valve, and a control unit for generating a control signal for the actuator based on information about the pressure measured at the feed port.

A hydraulic system for an agricultural system includes a hydraulic circuit and a bi-directional filter disposed on a bi-directional fluid line of the hydraulic circuit. The bi-directional filter includes a check valve fluid line having a check valve configured to block a fluid from flowing through the check valve fluid line in a first direction and to enable the fluid to flow through the check valve fluid line in a second direction, opposite the first direction, and a filter fluid line having a filter configured to enable the fluid to flow through the filter fluid line in the first direction and the second direction. The filter is configured to block particles that are greater than a threshold size from passing through the filter fluid line, and the filter fluid line is in a parallel flow configuration with respect to the check valve fluid line.

This invention relates to hydraulic energy storage and management systems. In particular, this invention relates to a hydraulic energy management system that has a reconfigurable energy storage and release capability that adjusts to varying available energy input and power demand output requirements. The hydraulic energy management system can be resized by a hydraulic bridge circuit to permit hydraulic power units to be added or removed, both physically and operationally, to capture available energy over time, adjust to peak demand cycles, and maintain power output in the event of a failure of a portion of the system.

A method of controlling an actuator includes switching a primary solenoid valve to a first mode to fluidically connect a supply pressure source to a control chamber of a pilot valve. A fluid from the supply pressure source is directed through the primary solenoid valve to fill the control chamber of the pilot valve and put the pilot valve in a first position. The first position fluidically connects a second chamber of the actuator to a return pressure source. The actuator includes a cylinder between the first chamber and the second chamber and a rod attached to the cylinder. The fluid from the supply pressure source is directed into the first chamber of the actuator to move the cylinder and the rod in a first direction while the pilot valve is in the first position.

The subject matter of this specification can be embodied in, among other things, a method that includes controlling, by a first fluid valve, a first fluid flow to a first fluid actuator, actuating, by the first fluid actuator, an output, controlling, by a second fluid valve, a second fluid flow to a second fluid actuator, and actuating, by the second fluid actuator, the output.

A control system includes a closing unit including a tank including a usable volume of the control system, at least one primary pump configured to pump hydraulic fluid from the usable volume of the tank, a plurality of valves, and a first pressure transducer disposed between the at least one primary pump and at least one valve of the plurality of valves. The at least one primary pump, the pressure transducer, and the at least one valve of the plurality of valves are hydraulically connected with the tank. The first pressure transducer manages a start-stop operation of the at least one primary pump. Hydraulic fluid within the control system has a predetermined static pressure. The at least one pump is powered by an electric energy source.