摘要:
A pressure compensation valve is constructed with a valve establishing and blocking a communication between an inlet port and an outlet port, a pressure receiving chamber, a piston driven by a load pressure within the pressure receiving chamber and shifting the valve in blocking direction, an intermediate pressure receiving chamber communicated with the inlet port via a first conduit and pushing the valve in blocking direction by the pressure therein, and a pressure variable relief valve for relieving a pressurized fluid in the intermediate pressure chamber to the outlet port via a second conduit.
摘要:
Simultaneous operation efficiency in a case where a plurality of actuators are operated by one or a plurality of hydraulic pumps is improved. A delivery pressure passage (1a) of one hydraulic pump (1) and that (1a) of the other hydraulic pump (1) communicate with each other through a first short-circuit passage (39) via a pair of check valves (38, 38), and an unload valve (40) is provided in this first short-circuit passage (39). The load pressure introduction passages (6, 6) on the left and right hydraulic pumps (1, 1) communicate with each other through a second short-circuit passage (36) via a pair of check valves (35, 35), and a relief valve (37) is provided in this short-circuit passage (36). The unload valve (40) is unloaded by the differential pressure between the pump delivery pressure in the first short-circuit passage (39) and the load pressure in the second short-circuit passage (36), whereby a single relief valve (37) carries out a relieving operation both at the time of flow merging and at the time of flow branching to equalize the maximum pump delivery pressures. The set pressure of the relief valve (37) can be a high level so as to relieve the valve (37) under a predetermined high load pressure, whereby the relieving operation can be arbitrarily controlled.
摘要:
In a control valve system provided with a plurality of valves for controlling a hydraulic equipment such as hydraulic cylinders, there are employed a plurality of valves each of which does not interfere with each other in operation and requires a minimum mounting space in the system to enable the system to be a small-sized system having a construction easily adapted to control a plurality of hydraulic equipments. The control valve system comprises: a valve (10) assuming a rectangular parallelepiped form; a first (11) and a second (12) pump port passage formed in an upper portion of a valve housing of the valve (10) so as to be parallel to each other; a tank port passage (13) formed in a lower central portion of the valve housing; a first (14) and a second (15) port passage vertically formed in the valve housing so as to separately open into an upper surface of the valve housing to communicate with each of pressure chambers of the hydraulic equipment; and a plurality of valves (19, 20, 23, 24) inserted into a plurality of valve receiving bores formed in the valve housing so as to shut off desired ones of these port passages from the remaining port passages.
摘要:
A transmission is provided which has a very compact system configuration and is capable of exerting high energy efficiency over all speed regions from a low speed region to a high speed region, while providing improved operability free from a torque shortage. To this end, the transmission has an input shaft, an intermediate output shaft, a planetary gear mechanism, a first pump-motor, and a second pump-motor connected to the first pump-motor, the input shaft being coupled to a first element of the planetary gear mechanism, the second pump-motor being coupled to a second element of the planetary gear mechanism, the intermediate output shaft being coupled to a third element of the planetary gear mechanism, and the transmission further comprising a switching mechanism for selectively coupling the first pump-motor to either the input shaft or the intermediate output shaft.
摘要:
A vehicle advances forward while turning to the right when an operating lever is tilted forward and to the right, that is, being operated in a direction intermediate between the forward direction and right-hand direction. Only an output signal of the component corresponding to the forward direction is preserved when the operating lever is released. The component corresponding to the right-hand direction returns to the neutral position, and the signal output is brought to zero. The vehicle therefore moves only forward. The operating position can thus be preserved and a signal output state can be held for a single directional component selected from longitudinal and transverse direction components when operating the operating lever device which is tilted along the directional components in both longitudinal and transverse directions.
摘要:
A hydraulically actuated breaker with a lost-motion preventing device includes a cylinder portion (26) defining a first chamber (23) constantly communicated with a hydraulic pressure source (47) and having a small pressure receiving area for upwardly moving a piston (22) and a second chamber (24) having a large pressure receiving area for downwardly moving the piston, by inserting the piston into a piston bore (21) of a breaker main body (20); a chisel (28) inserted within a chisel insertion hole (27) of the breaker main body in opposition to the piston; a main switching valve (40) being switched between a first position (E) communicating the second chamber with a tank (48) and a second position (F) communicating the second chamber with the hydraulic pressure source; and a valve mechanism (30) placing the main switching valve at the first position when the piston is in an effective lower stroke end position, placing the main switching valve at the second position when the piston is in an effective upper stroke end position, and maintaining the main switching valve at the second position when the piston is lowered beyond the effective lower stroke end position.
摘要:
A travelling control circuit for a hydraulically driven type of travelling apparatus is provided. The circuit has a hydraulic pump, left and right hand side directional control valves provided parallel to each other in a discharge path of the hydraulic pump, a left hand side first and second circuit and a right hand side first and second circuit. Furthermore, the output sides of the left hand side and right hand side directional control valves are connected with a left and right hand side travelling purpose hydraulic motor, respectively. In addition, a pressure compensating valve is provided with each of the first and second circuits to control the opening between an inlet port and an outlet port in response to a difference in pressure between a self load pressure and a maximum load pressure of the load pressures of the left and right hand side travelling purpose hydraulic motors, thereby compensating a pressure in the fluid. When the pressurized fluid is compensated, the pressure compensating valves establish communication between the left hand side and the right hand first circuits and between the left hand side and the right hand side second circuits. When communication between the inlet port an the outlet port is blocked or substantially blocked, the pressure compensating valves block communication between the left hand side and the right hand side first circuits and communication between the left hand side and the right hand side second circuits, respectively.
摘要:
A directional control valve unit includes a first actuator port connected to a raising side chamber of a working machine cylinder. In addition, a second actuator port is connected to a lowering side chamber of the working machine cylinder. A regeneration passage makes the second actuator port communicate with a regeneration port through a check valve. A main spool is adapted to supply a pressure oil to the second actuator port and to make the first actuator port communicate with a tank port and the regeneration port by moving the main spool in one direction. The directional control valve unit also includes a switching device for switching the maximum moving distance of the main spool in the one direction in a plurality of stages.
摘要:
A pressure compensation valve has a check valve portion with a check valve bore with an inlet port and an outlet port in a valve body, a valve in the check valve bore for establishing and blocking communication between the inlet port and the outlet port, a pressure reduction valve portion constructed by forming a pressure reducing valve bore having a first port, a second port and a third port and being coaxial with the check valve bore in the valve body, a spring-biased spool in the pressure reduction valve bore to define a first pressure chamber communicating with the first port and a second pressure chamber communicating with the third port at both sides, making the second port communicate with the third port by a pressure of the first pressure chamber, and blocking communication between the second port and the third port by the pressure in the second pressure chamber.
摘要:
An operating valve assembly with a pressure compensation valve, comprises a spool for selectively establishing and blocking communication between a pump port, an output port and a main tank port, being disposed within a spool bore of a valve body, and a pressure compensation valve being provided between the output port and the actuator port. The pressure compensation valve has a piston pressed in the closing side by a load pressure acting on a compensation pressure acting portion, and a valve provided integrally with the piston for selectively establishing and blocking communication between the output port and the actuator port, and actuated for opening by the output port pressure acting on a portion to be compensated, the compensation acting area being equal to the area to be compensated. A pilot valve for selectively establishing and blocking communication of a pressure receiving portion of the piston of the pressure compensation valve with a tank, and a shuttle valve supplying the pressure of higher pressure side among the load pressure and the actuator port pressure to a compensation pressure acting portion of the pressure compensation valve, are provided.