An example valve includes a housing, a sleeve disposed within the housing and having a first end and a second end opposite the first end, and the sleeve includes a plurality of sleeve protrusions at the first end and a plurality of fluid flow channels are formed between adjacent sleeve protrusions, a seal carrier disposed within the sleeve and having a carrier protrusion that extends from the second end of the sleeve and abuts against an interior surface of the housing, and an end cap mounted to the housing such that the plurality of sleeve protrusions abut against the end cap.

To make it possible to control supply, discharge, and recycled flow rates independently of each other for the boom cylinder in a construction machine comprising first and second boom spool valves respectively connected to first and second hydraulic pumps. When the boom cylinder is contracted, the first boom spool valve is configured to control the recycled flow rate from head side oil chamber to rod side oil chamber, the second boom spool valve is configured to control the discharge flow rate from head side oil chamber to oil tank, and both first and second boom spool valves are configured not to supply pressure oil from first and second hydraulic pumps to the boom cylinder.

The present disclosure relates to systems that use a single proportional valve to control raising and lowering of a load. The present disclosure also relates to proportional valves that provide proportional flow control in first and second opposite flow directions through the proportional valve.

There is provided a construction machine that is capable of measuring a minute leakage flow rate of a one-sided tilting variable displacement hydraulic pump. The construction machine includes a pressure sensor that detects a pressure of a hydraulic pump, a bleed-off adjusting device that is enabled to adjust a bleed-off flow rate of the hydraulic pump, and an input device that gives an instruction for measurement of a leakage flow rate of the hydraulic pump. The controller is configured to measure, when the controller determines that the operation device is in a non-operated state and when a measuring command is inputted from the input device, a pressure of the hydraulic pump while changing a control command value for the bleed-off adjusting device in a state in which a flow rate of the hydraulic pump is maintained, and calculate the leakage flow rate of the hydraulic pump on the basis of the control command value for the bleed-off adjusting device at the time that the pressure of the hydraulic pump is stabilized at a predetermined pressure.

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.

Systems and methods for determining a pre-charge gas pressure in a gas-charged hydraulic accumulator are disclosed. For example, systems and methods for determining pre-charged gas pressure of a gas-charged hydraulic accumulator included as part of a vehicle are disclosed. Further, the present disclosure provides for determining a pre-charge gas pressure of a gas-charged hydraulic accumulator using a position sensor. The accumulator may form part of a hydraulic system used to move one part of the vehicle relative to another.

A vehicle includes a chassis, a controllable vehicle component, a hydraulic circuit, a heater, a temperature sensor, and a controller. The hydraulic circuit includes a reservoir configured to store hydraulic fluid, a pump positioned to drive the hydraulic fluid from the reservoir and throughout the hydraulic circuit, and an actuator positioned to selectively receive the hydraulic fluid from the pump to selectively operate the controllable vehicle component. The heater is positioned to facilitate selectively heating the hydraulic fluid. The temperature sensor is positioned to acquire temperature data indicative of a temperature of the hydraulic fluid. The controller is configured to monitor the temperature of the hydraulic fluid and selectively activate at least one of the heater or the pump to thermally regulate the hydraulic fluid (i) to maintain the hydraulic fluid within a target temperature range and (ii) independent of (a) an operator input and (b) engagement of the actuator.

A control valve assembly for a load handling vehicle such as forklift comprises a valve body having a bore and a spool located within the bore that is axially movable along the bore between at least two operating configurations. The valve body includes a service port connected to a hydraulic actuator, a pressure port connected to a pump, and a tank port connected to a hydraulic tank reservoir. The valve is reconfigurable between first and second operating configurations. In the first operating configuration the spool defines a fluid pathway connecting the pump port, the service port and the tank port such that in a first flow direction fluid is able to flow from the pressure port to the service port and the tank port, and in a second flow direction fluid is able to flow from the service port to the pressure port and the tank port. The spool is also controllable in the first operating configuration to variably restrict flow to the tank port. In the second operating configuration the spool defines a fluid pathway connecting the pressure port and the actuator port, and is controllable to variably restrict flow between the pressure port and the actuator port.

A hydraulic system (1, 50) for a load handling vehicle comprises lifting actuator (2, C1) that operates in a load lifting mode in which a load is induced on the actuator, and a load lowering mode in which the actuator provides hydraulic power PI to the hydraulic system. An auxiliary hydraulic actuator (4, 6, 8, C2) is also provided that has a hydraulic power demand P2. A hydraulic pump (10, 58) directs hydraulic power to the hydraulic lifting actuator and the at least one auxiliary hydraulic actuator. The hydraulic system is configured such that when the hydraulic lifting actuator is in the load lowering mode, it is required to simultaneously actuate the at least one auxiliary hydraulic actuator, and PI is greater than or equal to P2, hydraulic power may be channelled directly to the auxiliary hydraulic actuator from the hydraulic lifting actuator in order that the at least one auxiliary hydraulic actuator is actuated entirely by the hydraulic power from the hydraulic lifting actuator, and without the use of the pump.

The present disclosure relates to a hydraulic valve arrangement comprising a first pilot operated proportional directional control valve having a first valve member that is displaceable in a first and a second axial direction for controlling direction of supply and discharge of hydraulic fluid to and from a hydraulic actuator, a first proportional electro-hydraulic control valve for controlling displacement of the first valve member in the first axial direction, a second proportional electro-hydraulic control valve for controlling displacement of the first valve member in the second axial direction, and a second pilot operated proportional control valve having a second valve member configured to be controlled by the first and second proportional electro-hydraulic control valves via a shuttle valve arrangement. Individual meter-in and meter-out control of the hydraulic actuator is providable by having the second pilot operated proportional control valve configured to operate as a meter-in valve of the hydraulic actuator and the first pilot operated proportional directional control valve configured to operate as a meter-out valve of the hydraulic actuator, or by having the first pilot operated proportional directional control valve configured to operate as a meter-in valve of the hydraulic actuator and the second pilot operated proportional control valve configured to operate as a meter-out valve of the hydraulic actuator. The present disclosure also relates to a vehicle comprising a hydraulic actuator and a hydraulic valve arrangement for controlling the motion of the hydraulic actuator.