A semi-closed loop hydraulic circuit includes a prime move, a first hydraulic circuit operatively coupled to the prime mover, and a second hydraulic circuit operatively coupled to the prime mover. The second hydraulic circuit is fluidly coupled to the first hydraulic circuit.

A pressure control device includes a body having a groove-shaped flow path including a groove part and a widened part, and a filter unit capturing foreign matters mixed in a fluid which passes through the groove-shaped flow path; the filter unit having a frame body including a through hole part and a filter member in a planar plate shape disposed with respect to the through hole part, and the filter unit being accommodated in the widened part. The frame body has: a first part having a first shape, a second part having a second shape smaller than the first shape, and a step part located at a boundary part between the first part and the second part The second part has a storage part provided in a penetrating manner on a bottom part side of the groove-shaped flow path and storing the captured foreign matters.

An oil supply system for a vehicle includes a plurality of oil pumps, suction oil passages, and a communication passage. The oil pumps are independently operational. The suction oil passages each connect an associated one of suction portions of the plurality of oil pumps and a common oil strainer. The communication passage connects the suction oil passages.

A hydraulic drive device for a cargo vehicle includes a hydraulic cylinder supplying and discharging of hydraulic oil, an operation member that operates the hydraulic cylinder, a hydraulic pump, a lowering oil path connecting the hydraulic cylinder and the hydraulic pump, an operation valve disposed in the lowering oil path, a bypass oil path that branches off from the lowering oil path, a bypass flow rate control valve disposed in the bypass oil path and that controls a bypass flow rate, and a resistance element that is disposed closer to the hydraulic cylinder than the operation valve in the lowering oil path and that increases a fluid resistance. A pilot flow path of the bypass flow rate control valve is connected to a part of the lowering oil path between the hydraulic cylinder and the resistance element.

A control device is disclosed for at least one hydraulic working section (A, B), which can be connected to a pressure supply source (P) and a return flow (T) via a hydraulic supply circuit and a control valve (34) supplied with a pilot pressure, the device comprising an emergency shutdown system (32) having a pilot solenoid valve (16) and an additional valve (14). Said control device is characterised in that both the hydraulic energy flow from the pressure supply source (P) to at least one of the respective working sections (A, B) and the pilot pressure supply to the control valve (34) can be suppressed by means of the pilot solenoid valve (16) via the additional valve (14).

In one or more embodiments, a system for predicting health of a hydraulic pump comprises a reservoir tank temperature sensor to measure a temperature of a reservoir tank. The system further comprises a hydraulic pump temperature sensor to measure a temperature of the hydraulic pump. Also, the system comprises a differential pressure sensor to measure a differential pressure across a filter associated with the hydraulic pump. Further, the system comprises a processor(s) to determine a differential temperature by subtracting the temperature of the reservoir tank from the temperature of the hydraulic pump, to compare the differential temperature to a differential temperature threshold, to compare the differential pressure to a differential pressure threshold, and to generate an alert signal indicating failure of the hydraulic pump, when the processor(s) determines that the differential temperature exceeds the differential temperature threshold and the differential pressure exceeds the differential pressure threshold.

There is disclosed a method of generating an alert relating to a hydraulic actuation system for actuating a hydraulic cylinder, the hydraulic control system comprising a hydraulic fluid tank and a hydraulic fluid filter. The method comprises monitoring the pressure drop over the hydraulic fluid filter; determining a rate of change characteristic relating to the rate of change of pressure drop over at least one time period in which there is a hydraulic fluid flow through the hydraulic fluid filter; determining whether the hydraulic fluid is dirty based on at least the rate of change characteristic; and generating an alert if it is determined that the hydraulic fluid is dirty.

A nozzle of or for a servo valve comprises a nozzle element having a fluid outlet at a first axial end and a tubular body extending from the first end to an opposed, second axial end. The nozzle further comprises a plug element mounted in and closing the second axial end of the tubular body, thereby defining an internal cavity within the tubular body. One or more openings are formed through the tubular body to fluidly communicate with the internal cavity. A filter may be mounted across the internal cavity at a position axially intermediate the openings and the fluid outlet.

A method is described for manufacturing a three-dimensional product, in particular a hydraulic element, the method encompassing at least the following method steps: Providing a first section of the product to be manufactured, which includes at least one first connection point for a second section of the product to be manufactured; and producing the second section by an additive manufacture in which the at least one first connection point of the first section is used as a substrate for the additive manufacture of the second section.

A dust-proof and heat-control device for hydraulic cylinder is provided, including: a fixing sleeve, an annular fan mechanism, a sealing end cap and a dust cover; wherein the fixing sleeve is sleeved on a cylinder barrel of the hydraulic cylinder, the annular fan mechanism is sleeved on the fixing sleeve, the sealing end cap is disposed on an end of the cylinder barrel, a piston rod of the hydraulic cylinder passes through the sealing end cap and the dust cover, the dust cover is fixed on the piston rod, the annular fan mechanism, the dust cover and the hydraulic cylinder enclose an inner space, a side wall of the dust cover is provided with an opening communicating with the inner space, and a filter screen is mounted at the opening. The device and method can achieve good dust proof and heat control effect on axially reciprocating telescopic hydraulic cylinder.