摘要:
A control device for multiple hydraulic actuators which is capable of rapidly increasing a discharge pressure of a variable pump (1) to prevent a decrease in discharge quantity of the variable pump even when one of the actuators is required to be fed with hydraulic fluid in a micro-amount under a low pressure. An operating valve (42) of a spin motor (39) is connected on a downstream side thereof through a converging passage (44) to a feed side of a boom cylinder (37) and the converging passage is provided with a change-over valve (67) which is changed over to an open position when an operating valve (40) for operating the above-described boom cylinder is changed over.
摘要:
A device for controlling multiple hydraulic actuators to protect a system from an overpressure caused by increasing the load on an individual actuator. By controlling the supply of hydraulic fluid to a pair of cylinders (18,20) each associated with a pilot valve (25,34,45) so that each cylinder always has enough fluid pressure to operate, the device of the present invention prevents the shutdown of the device caused by too much fluid going to the actuator operating at the maximum pressure. Thus all actuators continue to operate even if one is overpressured.
摘要:
A load-sensing active hydraulic control device which includes a service port connected to a breaker or scissors in a power shovel of the like and is capable of preventing an excessive increase in pressure on the side of the service port from affecting other actuators. An on-off valve (34) is connected to a load detecting passage (33) of a change-over valve (3) connected to the side of a service port and is closed to prevent a pressure on the side of the service port from being fed back to a regulator when a load pressure on the side of a main actuator (2) is equal to or exceeds a set pressure.
摘要:
A load-sensing active hydraulic control device is disclosed in which a plurality of cylinders (19,20) are connected in parallel and fed with hydraulic fluid from a variable discharge pump (1), thereby to control the variable discharge pump depending on horsepower constant control characteristics and which is capable of preventing, when one cylinder (20) is increased in load pressure, actuation of the other cylinder (19) from being stopped due to a decrease in the amount of hydraulic fluid discharged from the pump. A pilot valve (25) is provided which is changed over by a pressure actuation of a passage (18) of the one cylinder (20). The pilot valve is open to communicate a pilot chamber (4b) of a change-over valve (4) with a tank (T) when a pressure in the passage approaches a set pressure of an overload relief valve (22) of the passage. This results in a degree of opening of a variable orifice (6) of the change-over valve being reduced to decrease the amount of hydraulic fluid fed to the cylinder (20), thereby to ensure feeding of hydraulic fluid to the cylinder (19) correspondingly.
摘要:
A control device for multiple hydraulic actuators which is capable of rapidly increasing a discharge pressure of a variable pump (1) to prevent a decrease in discharge quantity of the variable pump even when one of the actuators is required to be fed with hydraulic fluid in a micro-amount under a low pressure. An operating valve (42) of a spin motor (39) is connected on a downstream side thereof through a converging passage (44) to a feed side of a boom cylinder (37) and the converging passage is provided with a change-over valve (67) which is changed over to an open position when an operating valve (40) for operating the above-described boom cylinder is changed over.