The present invention provides an engineering machinery hydraulic system with compensation differential pressure controllable, uses an electronic pressure compensating valve to solve the problem of flow mismatch under conditions of pressure over-limit and flow saturation, and realizes proportional shunt control and high-precision flow distribution of the system. The engineering machinery hydraulic system disclosed in the present invention has the advantages of low energy consumption, fast response speed, and high flow control precision.

An example valve assembly is configured: generate a valve load-sense pressure signal indicative of a pressure level at a workport of an actuator; generate a pilot fluid signal to be communicated to a worksection of a valve assembly to enable shifting a spool in the worksection; compare a first pressure level of the valve load-sense pressure signal to a second pressure level of the pilot fluid signal; and communicate the pilot fluid signal to a load-sense port fluidly coupled to a load-sensing source of pressurized fluid when the second pressure level of the pilot fluid signal exceeds the first pressure level of the valve load-sense pressure signal.

A load sense pressure regulating system is provided. The load sense pressure regulating system can be operable between a flow regulation mode and a pressure limiting mode. When the load sense pressure control system is in the flow regulation mode, flow between a load sense inlet and a pilot vent are metered by a main poppet. The load sense pressure regulating system can also include a control valve downstream from the pilot vent that is configured to control a relief setting of a relief valve to regulate the load sense pressure within a desired operating range.

The invention relates to a valve, which is characterized in that between a neutral position (38) of a control spool (STS) and one of its end positions (34, 42) a regeneration position (36) is provided, in which two utility ports (A, B) are interconnected in a fluid-conveying manner, or a floating position (40) is provided, in which these utility ports (A, B) are interconnected in a fluid-conveying manner. The invention relates to a further valve, which is characterized in that by a further motion of the control spool (STS) in the same direction, as that, in which a fluid connection is established between the utility ports (A, B) starting from the neutral position (38), this fluid connection is interrupted.

A hydraulic drive device for an industrial vehicle includes a tank, a hydraulic pump, a capacity control valve, a plurality of hydraulic cylinders, a plurality of direction switching valves, a first hydraulic oil passage, a second hydraulic oil passages, a pilot line, a relief valve, a relief pressure setting portion, a plurality of operation detecting portions, and a control unit. The control valve controls the hydraulic pumps so that a differential pressure between a discharge pressure of the hydraulic pump and a pilot pressure of the pilot line is to be a predetermined pressure. The control unit controls the relief pressure setting portion.

The invention relates to a control device for a hydraulic consumer (22), susceptible to vibrations, comprising a valve (24) having a control spool (40), which can be controlled by means of an actuating device (46), wherein the valve (24) has a pressure supply port (P), to which a pressure compensator valve can be connected, which can be supplied with pressure fluid from a pressure supply device, wherein the actuating device (46) has a motor (74) and wherein a load-pressure-dependent force on the control spool (40) can be generated by means of a control device (66). In accordance with the invention, this force at the control spool (40) acts on an electronic motor controller (208) of the DC motor (74), which detects a change of the force and acts as a damping of the vibrations of the consumer (22) against this change of force.

A work machine includes an electric drive system. The work machine includes a prime mover, a machine controller, and a hydraulic control system. The hydraulic control system includes a pump, a control valve and a retarding control valve. The pump is configured to supply pressurized fluid to the hydraulic control system via a supply line. The control valve is fluidly coupled to the pump via the supply line, and includes a pressure relief valve. The retarding control valve is fluidly connected to the pump and the control valve. The retarding control valve includes a solenoid valve, an orifice and a check valve. The solenoid valve is coupled to the machine controller, the orifice restricts a flow of the pressurized fluid through the supply line, and the check valve is coupled to a discharge line, which branches from a point along the supply line between the solenoid valve and the orifice.

An example valve assembly is configured: generate a valve load-sense pressure signal indicative of a pressure level at a workport of an actuator; generate a pilot fluid signal to be communicated to a worksection of a valve assembly to enable shifting a spool in the worksection; compare a first pressure level of the valve load-sense pressure signal to a second pressure level of the pilot fluid signal; and communicate the pilot fluid signal to a load-sense port fluidly coupled to a load-sensing source of pressurized fluid when the second pressure level of the pilot fluid signal exceeds the first pressure level of the valve load-sense pressure signal.

A downhole tractor having a hydraulic system for driving a plurality of hydraulic cylinders and a plurality of hydraulic motors. The system comprises: a hydraulic power pack; a first hydraulic supply line for supplying hydraulic fluid to the plurality of hydraulic cylinders; a second hydraulic supply line for supplying hydraulic fluid to plurality of hydraulic motors; a valve section comprising a respective part of first hydraulic supply line and a further respective part of second hydraulic supply line, valve section further comprising an inlet for receiving hydraulic fluid, and a set of valves, and a hydraulic bypass supply line coupled to hydraulic power pack for supplying hydraulic fluid directly to the inlet of valve section bypassing at least part of first hydraulic supply line and second hydraulic supply line. The first and the second hydraulic supply line each comprise two parts connected via respective part in the valve section. Each respective part is connected to a respective sub-set of plurality of hydraulic components. The valve section configured for individually controlling flow of hydraulic fluid into each respective part of hydraulic supply lines.

A hydraulic system for a feed delivery unit according to the present disclosure may include a pump configured to supply a total flow, the pump including at least one suction port configured to be connected to a reservoir and at least one outlet port configured to be connected to a supply line, a control valve fluidly coupled to the pump and including a plurality of valve sections, the control valve being coupled to the pump such that the total flow supplied by the pump is distributed among the plurality of valve sections, and wherein each valve section of the plurality of valve sections is configured to control a direction of flow of a portion of the total flow, and a plurality of hydraulic motors fluidly coupled to the pump via the control valve, each of the motors being configured to drive a respective auger of the feed delivery unit.