Hydraulic fluid flushing valve for hydrostatic units usable in closed hydraulic circuit propel applications, having a flushing valve housing with a first inlet port connected to a first working line, a second inlet port connected to a second working line, and a discharge port for draining hydraulic fluid. A two-sided flushing valve flushing valve spool which can be shifted is mounted within the flushing valve housing in a cylindrical valve bore, which, in a shifted position, enables a fluid flow from one of the first or the second inlet port at which the lower hydraulic pressure is present, to the discharge port. The flushing valve spool includes on each side a pressure surface each of which is connected to one of the two inlet ports. At each side of the flushing valve spool a flushing valve spring is located in the flushing valve housing in such a manner that, when the flushing valve spool is in its centre, non-shifted position, at each side of the flushing valve spool a distance between a spring contact surface on the flushing valve spool and a spring support surface in the flushing valve housing is greater than the axial length of the corresponding flushing valve spring.

A hydraulic fluid de-aeration device for a hydraulically actuated variable valve actuation system is provided. The device includes a bridge and a de-aeration chamber having an upper chamber, a lower chamber, and a central axis. A vent pipe is arranged along the central axis of the de-aeration chamber and can include at least one vent hole. The bridge is arranged such that hydraulic fluid flowing from the bridge is directed towards an outer wall of a top portion of the lower chamber. The device includes a cover that integrates the upper chamber with a vent hole for air that is expelled from the hydraulic fluid. An optional gasket or plate configured with at least one vent hole can be arranged between the upper and lower chamber. The vent pipe can be arranged within the cover and extend through the upper chamber to the lower chamber.

This invention relates to a four-state adjustable air path structure. An air source is connected to an air storage tank and a first two-position three-way solenoid valve via a check valve. The first two-position three-way solenoid valve is connected to a second two-position three-way solenoid valve and a vent hole. The second two-position three-way solenoid is connected to a third two-position three-way solenoid valve and a port of a throttle valve. Another port of the throttle valve is connected to the third two-position three-way solenoid valve. The third two-position three-way solenoid valve is connected to an air tank. The present four-state adjustable air path structure simplifies processing and maintenance of a mechanical structure. Intellectual control of an operating speed can also be achieved. The present invention has advantages such as structural simplicity, low manufacturing costs, safe and reliable operation, long service life, and suitability for long-distance transmission.

An apparatus includes a drive mechanism, a first cylinder comprising a first piston coupled to the drive mechanism, and a second cylinder comprising a second piston. The first cylinder includes a first fluid reservoir and a second fluid reservoir, with the first piston disposed between the first fluid reservoir and the second fluid reservoir. The second cylinder includes a third fluid reservoir and a fourth fluid reservoir, with the second piston disposed between the third fluid reservoir and the fourth fluid reservoir. The apparatus further includes a first fluid line coupling the first fluid reservoir to the fourth fluid reservoir, and a second fluid line coupling the second fluid reservoir to the third fluid reservoir. The first piston comprises a threaded portion disposed in a threaded aperture of the first cylinder.

A vented pressurized gas-powered actuator includes a housing having a central longitudinal axis and an inner surface. The inner surface has a constant radius between first and second planes extending perpendicular to the axis. At least one vent groove extends from the inner surface in a direction away from the axis. The at least one groove has a first end intersecting the first plane.

Provided is a hydraulic drive system including: first and second pumps; a first main supply fluid line and an optional supply fluid line leading to the first pump; a second main supply fluid line leading to the second pump; a main manipulating device for the main actuator; an optional manipulating device for the optional actuator; a bleed-off flow rate regulating section to change the bleed-off flow rate for the second pump; and a bleed-off control section to operate the bleed-off flow rate regulating section to change the discharge flow rate of the second pump in accordance with a control operation applied to the main manipulating device and to make a bleed-off flow rate in a specific combined manipulation state with simultaneous performance of a specific main control operation and an optional control operation be smaller than that in a single main manipulation state.

The present disclosure provides a heat exchanger system for a servovalve, comprising a base comprising a supply port in fluid communication with a return port, a first passage for fluid connection to a source of cooling fluid, and a second passage in fluid communication with the return port. The system further comprises one or more pipes located over a surface of the base, the one or more pipes fluidly connected between the first passage and the second passage, such that in use cooling fluid may flow from the first passage to the second passage via the network of pipes.

The present disclosure provides a heat exchanger system for a servovalve, comprising a base comprising a supply port in fluid communication with a return port, a first passage for fluid connection to a source of cooling fluid, and a second passage in fluid communication with the return port. The system further comprises one or more pipes located over a surface of the base, the one or more pipes fluidly connected between the first passage and the second passage, such that in use cooling fluid may flow from the first passage to the second passage via the network of pipes.

A submersible heat-exchanging apparatus for installation into storage tanks used for containing industrial oils. The apparatus comprises a cylindrical heat-exchange component with one end sealingly engaging a terminal plug and the other end sealingly engaging and communicating with a coupling manifold having opposed inflow and outflow ports. A flow-directing elongate insert is provided with one end configured to engage the coupling manifold interposed the inflow and outflow ports, and the other end provided with an aperture and configured for abutting the terminal plug. The flow-directing elongate insert slidingly contacts and cooperates with the inner walls of the heat-conductive conduit thereby partitioning the heat-conductive conduit into two opposed fluid transmission channels wherein one channel communicates with the inlet port and the other channel communicates with the outlet port. The coupling manifold sealingly engages an aperture provided in the storage tank whereby the heat-exchange component extends into the tank.

A change-over valve comprises a spool housed in a spool housing, and a pilot chamber facing at least an end of the spool. An axial passage is formed in the spool along the axial direction. While being connected to a pilot chamber, the axial passage communicates with a tank passage via a small hole having an opening on an outer periphery of the spool in accordance with displacement of the spool, to discharge the air in the pilot chamber to the tank passage. Since the axial passage is formed at a location offset from a center axis of the spool, a length of the small hole is shortened and the small hole is easily processed.