An oil returning valve set with multi-stage throttling control includes an oil returning channel implemented in oil in an oil hydraulic equipment. The two ends of the oil returning channel are connected to a pressurized oil collecting cavity and a pressurized oil discharging cavity respectively. A plurality of throttling valve plugs and oil returning valve plug are arranged in the oil returning channel, and a normally-open draining gap is also formed among the plurality of throttling valve plugs. When the oil returning valve plug is opened, a plurality of the throttling valve plugs are arranged in series to generate multi-stage throttling oil hydraulic draining control, which improves the problem that the valve opening allowance of the throttling valve for oil returning and pressure relief of traditional oil hydraulic equipment is not sufficient.

A hydraulic system, comprising: a hydraulic pump, a hydraulic load, and an electric machine. The electric machine working as an electric generator and mechanically coupled with said hydraulic pump. A low-pressure fluid tank and a valve assembly comprising one or more valves selectively fluidly connecting the hydraulic load with the low-pressure fluid tank.

A fluid system includes a variable-speed and/or a variable-torque pump to pump a fluid, at least one proportional control valve assembly, an actuator that is operated by the fluid to control a load, and a controller that establishes a speed and/or torque of the pump and a position of the at least one proportional control valve assembly. The pump includes at least one fluid driver that provides fluid to the actuator, which can be, e.g., a fluid-actuated cylinder, a fluid-driven motor or another type of fluid-driven actuator that controls a load. Each fluid driver includes a prime mover and a fluid displacement assembly. The fluid displacement assembly can be driven by the prime mover such that fluid is transferred from the inlet port to the outlet port of the pump.

The present invention relates to a mobile work machine, in particular to a wheeled loader, having a hydraulic circuit, having a pump for conveying a hydraulic medium through the hydraulic circuit, and having at least one control block having an inflow control edge and an outflow control edge for controlling the flow of the hydraulic medium, wherein the work machine has a working tool and a cylinder for actuating the working tool and wherein the cylinder has an outflow and in inflow for the hydraulic medium, and wherein the outflow is in fluid communication with the outflow control edge and the inflow is in fluid communication with the inflow control edge, and wherein the inflow control edge does not have any or has fewer fine control notches than the outflow control edge and thus works in a largely unrestricted manner, while the outflow control edge is equipped with one or more fine control notches so that with a pulling load at the working tool, the outflow control edge restricts the outflow amount through the outflow of the cylinder.

A hydraulic system is provided. The hydraulic system may include a fluid pressure source in fluid communication with a supply line, a return line in fluid communication with a tank, a hydraulic function having a workport, a first control valve having a first proportional solenoid, a second control valve having a second proportional solenoid, and a controller. The controller being configured to selectively energize the first proportional solenoid, the second proportional solenoid, or the first proportional solenoid and the second proportional solenoid to control a system pressure differential, defined between the return line and the workport, within a range that is defined by a sum of a first predefined range defined by the first control valve and a second predefined range defined by the second control valve.

A hydraulic system includes a hydraulic pump, a first hydraulic actuator, a second hydraulic actuator, a first control valve to control the first hydraulic actuator, a second control valve to control the second hydraulic actuator, a pressure increasing portion to increasing a pressure of the operation fluid, a first discharge fluid tube connected to any one of the first control valve and the second control valve and connected to the pressure increasing portion, a second discharge fluid tube connected to the first discharge fluid tube and configured to discharge the operation fluid, a float switching valve having an allowance position, a prevention position, and a float position, the allowance position blocking the second discharge fluid tube and allowing the operation fluid to flow to the pressure increasing portion, the prevention position unblocking the second discharge fluid tube and preventing the operation fluid from flowing to the pressure increasing portion.

A solenoid flow control valve includes: an inlet passage that allows an inlet port to communicate with a pilot pressure chamber; an outlet passage that allows the pilot pressure chamber to communicate with an outlet port; a fixed restrictor provided on the outlet passage; a pilot spool that closes the inlet passage when a solenoid is in a non-excitation state, whereas when solenoid is in an excitation state, opens inlet passage at an opening degree corresponding to an input current value to generate a pilot pressure corresponding to the input current value in pilot pressure chamber, the pilot spool opening a bypass passage when input current value is less and closes bypass passage when input current value is greater than or equal to the predetermined value; and a main spool that controls a flow rate from inlet to outlet port in accordance with the pilot pressure chamber's pilot pressure.

An example valve includes a first port fluidly coupled to a source of fluid, a second port fluidly coupled to an actuator, a third port fluidly coupled to a reservoir, and a fourth port configured to export a load-sense (LS) fluid signal. The valve can operate in: a neutral state, wherein fluid is allowed to flow from the second port to the third port, while the first port and the fourth port are blocked; a first actuated state, wherein fluid flow is throttled from the second port to the third port, while the first port and the fourth port remain blocked; or a second actuated state, wherein fluid flow from the second port to the third port is blocked, while fluid flow is allowed from the first port to the second port and from the second port to the fourth port.

A method and apparatus for remotely positioning a stabilizer wheel of a towable agricultural implement simultaneously, cooperatively and proportionally control the flow of hydraulic fluid to and from both the rod and base ends of the bore of a double-acting hydraulic cylinder, to hold the piston of the hydraulic cylinder at a target position determined from a desired position input signal corresponding to a desired position of the stabilizer wheel with respect to a frame of the agricultural implement.

The present invention provides an improved high-low hydraulic system for compacting machinery, such as balers, horizontal balers, compactors, transfer station compactors, and the like. The high-low hydraulic system comprises at least one double rotary pump, a plurality of directional control valves, a pilot-operated back pressure reducing valve, a flow control valve, a plurality of one-way valves, and a plurality of pressure switches. The high-low hydraulic system may be regenerative or non-regenerative and provides many advantages over conventional hydraulic systems. Such advantages include greater system efficiency due to a reduced back pressure during the time of the retraction stroke and clever flow sequencing, mitigation of hydraulic shocks at the beginning and end of compaction and retraction strokes, and reduced cycle time of the cylinder during operation due to the concurrent filling of the rod end side during decompression of the blind end side after the compaction stroke. Moreover, the present high-low hydraulic system allows for the cylinder to operate at three or more independent speeds. Additionally, the present high-low hydraulic system may also comprise an accumulator and pressure transducer that further assist with substantially maintaining a predetermined hydraulic pressure on the blind end side after the completion of the compaction stroke.