摘要:
In a hydraulic system which is biased to a minimum system pressure using a bias valve or other flow obstruction disposed in a tank line, there is provided in a bypass line to the bias valve an evacuating and filling valve through which the hydraulic system is first evacuatable and subsequently fillable with a hydraulic fluid. The valve closes the bypass when a differential pressure overcomes a preadjusted force of a spring element. For this purpose, the valve possesses a displaceably mounted valve body with an integrated throttle and a seal face which closes a through opening when the valve body is shifted against the bias force of the spring element due to the pressure difference.
摘要:
An assembly for machine leveling including a plurality of hydraulic cylinders having upper ends adapted for supporting the machine's base, a lower end, a shaft, and a port opening the cylinder; branch conduits having cylinder ends and pump ends, each branch conduit connecting to one of the ports; first shutoff valves connected to the branch conduits for alternatively permitting and resisting fluid flow within the branch conduits; a manifold conduit connected to the branch conduits; a hydraulic pump connected to the manifold conduit and adapted for raising hydraulic pressure within the manifold conduit to a shaft extending pressure; and an electrically modulated variable pressure relief valve connected to the manifold conduit and adapted for raising and lowering the hydraulic pressure.
摘要:
The present disclosure provides a pressure peak reduction valve for an excavator. The pressure peak reduction valve includes at least: a poppet seat which has an inlet port, and at least one communication hole which communicates with a hydraulic tank and is formed in an outer circumferential surface of the poppet seat; a main poppet which slides in the poppet seat; a poppet spring which is provided in the main poppet; a valve seat which has one end portion inserted into the main poppet so as to be in contact with one end portion of the poppet spring; a cone which is provided to be inserted into an openable hole formed at an end portion of the valve seat; an adjustment screw which is provided in the valve seat; and a piston which slides in the adjustment screw.
摘要:
A hydraulic drive including at least one hydraulic cylinder that includes a piston chamber, an annulus and a piston that separates the piston chamber from the annulus. The hydraulic drive further includes a first hydraulic pump that has a pump intake and a pump outlet, a directional control valve that has a first and a second switching position, and a second hydraulic pump. The second hydraulic pump has a direction of delivery that is consistent with the direction of delivery of the first hydraulic pump at the pump outlet, wherein the second hydraulic pump in the first switching position of the directional control valve is hydraulically connected with the piston chamber and the second hydraulic pump in the second switching position of the directional control valve is not hydraulically connected with the piston chamber.
摘要:
An aircraft hydraulic fluid heating system and method are disclosed. In one embodiment, pump characteristics of a hydraulic pump coupled to a reservoir are obtained. Further, total demand of the hydraulic fluid for hydraulically controlled flight controls in the aircraft is determined. Furthermore, the hydraulic fluid in the reservoir is dynamically heated based on the pump characteristics and the total demand of the hydraulic fluid.
摘要:
The invention relates to a device for applying a working force to a workpiece, using a working cylinder. The device includes a working piston, an actuation chamber that can be supplied with a hydraulic medium, a recirculation chamber that can be supplied with a gaseous medium and a force transmission device that co-operates with the working piston. This allows a transmission or an application of the working force to a workpiece that is as rapid as possible with a technical construction that is as simple as possible.
摘要:
A hydraulic drive apparatus in which a hydraulic pressure motor is driven and rotated depending on an operation position entered from an operation lever. An oil pressure control circuit and method which detect pressures of operation oils capable of driving the hydraulic pressure motor to rotate and a pressure of an operation oil supplied from a hydraulic pump to a directional control valve. The oil pressure control circuit varies a set pressure of a main relief valve in a manner that feeds current to an electromagnetic relief valve and varies a set pressure of an electromagnetic relief valve. As a result, the oil pressure control circuit carries out such a control that a pressure of an operation oil received from the hydraulic pump is higher than a pressure of an operation oil for driving and rotating the hydraulic pressure motor by a predetermined pressure.
摘要:
A load sensing hydraulic system includes two pumps, at least one hydraulic fluid consumer, and a pressure balance circuit. In the case of no demand from the consumer, hydraulic fluid flows from the pumps through the pressure balance circuit and to tank. In the case of demand from the consumer for hydraulic fluid at a flow rate less than or equal to the flow rate provided by the first pump, hydraulic fluid from the first pump flows to the consumer, and hydraulic fluid from the second pump flows to the tank. In the case of a demand from the consumer for hydraulic fluid at a flow rate greater than the capacity of the first pump, hydraulic fluid from both pumps flow to the consumer.
摘要:
A power machine includes one or more steerable wheels. The wheels are steerable using a hydraulic actuator to drive steering movement of the wheels. The power machine also includes steering angle sensors which sense the steering angle and provide a signal indicative of the angle at which the wheels are disposed relative to a longitudinal axis of the power machine. A hydraulic control system controls pressure of hydraulic fluid provided to the steering actuators based upon the steer angle position and desired change in position over time sensed by the steer angle sensors.
摘要:
An improved pressure-compensated hydraulic system for feeding hydraulic fluid to one or more hydraulic actuators. A remotely located, variable displacement pump provides an output pressure equal to a control input pressure plus a constant margin. A pressure compensation system requires that a load-dependent pressure be provided to the pump input through a load sense circuit. An isolator transmits the load-dependent pressure to the pump control input, while preventing fluid from leaving the load sense circuit and flowing to the remotely located pump. A valve section, which controls the fluid flow between the pump and actuator, has a pressure compensating valve with a piston and spool controlling a pressure differential across a main control valve orifice by moving within a bore in response to a pressure differential between a pump supply pressure and the load sense pressure. The piston and spool also separate to shut off fluid flow to the actuator when the back pressure from the load exceeds the pump supply pressure.