초록 ▼

A control system for a hydraulic vehicle having a pair of bidirectional travel motors driven by respective pumps via respective travel valves, and implement actuators, including a swing motor, driven by the pumps via two parallel connections of pilot-operated implement valves. For making possible th

A control system for a hydraulic vehicle having a pair of bidirectional travel motors driven by respective pumps via respective travel valves, and implement actuators, including a swing motor, driven by the pumps via two parallel connections of pilot-operated implement valves. For making possible the straight travel of the vehicle, either forwardly or rearwardly, while any of the implement actuators is being driven by either pump, a straight travel valve is provided for the on-off control of communication between the forward travel ports, and between the rearward travel ports, of the two travel motors. Normally held closed under spring pressure, the straight travel valve is pilot opened by a series connection of two straight travel control valves, which delivers pilot control fluid to the straight travel valve when the travel valves are both hand operated to set the two travel motors into rotation in the same direction. The straight travel control valves receive the pilot control fluid from implement control valves provided for the pilot actuation of the implement valves. Thus the two travel motors when set into rotation in the same direction are driven by the combined power fluid from the two pumps if then any of the implement control valves is being operated for activating the corresponding implement actuator or actuators.

대표청구항 ▼

A hydraulic vehicle control system comprising: (a) first and second pumps for supplying power fluid; (b) implement actuator means; (c) first and second bidirectional travel motors each having a forward travel port for the reception of the power fluid for rotation in a forward direction and a rearwar

A hydraulic vehicle control system comprising: (a) first and second pumps for supplying power fluid; (b) implement actuator means; (c) first and second bidirectional travel motors each having a forward travel port for the reception of the power fluid for rotation in a forward direction and a rearward travel port for the reception of the power fluid for rotation in a rearward direction; (d) first implement valve means for controlling the delivery of the power fluid from the first pump to the implement actuator means; (e) second implement valve means for controlling the delivery of the power fluid from the second pump to the implement actuator means; (f) a first travel valve connected in parallel with the first implement valve means for controlling the delivery of the power fluid from the first pump to the forward and rearward travel ports of the first travel motor; (g) a second travel valve connected in parallel with the second implement valve means for controlling the delivery of the power fluid from the second pump to the forward and rearward travel ports of the second travel motor; (h) a straight travel valve for the on-off control of communication between the forward travel ports, and between the rearward travel ports, of the first and second travel motors, the straight travel valve being normally held closed to block communication therebetween, the straight travel valve being pilot actuated to open; and (i) straight travel control means for causing the straight travel valve to allow communication between the forward travel ports, and between the rearward travel ports, of the first and second travel motors when the first and second travel valves are both actuated to set the first and second travel motors into rotation in the same direction, said straight travel control means comprising a source of pilot control fluid; and straight travel control valve means responsive to the actuation of the first and second travel valves for delivering the pilot control fluid to a pilot port of the straight travel valve when the first and second travel valves are both actuated to set the first and second travel motors into rotation in the same direction; said straight travel control valve means further comprising a first straight travel control valve normally blocking the pilot control fluid and allowing the pilot control fluid to pass therethrough on actuation of one of the first and second travel valves in either direction; and a second straight travel control valve for permitting the pilot control fluid from the first straight travel control valve to pass therethrough only when the other of the first and second travel valves is actuated in the same direction as said one of the first and second travel valves.