Hydraulic vehicle control system

Claim 2

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.

Claim 3

The hydraulic vehicle control system of claim 1 further comprising implement control valve means connected between the source of pilot control fluid and the first and second implement valve means for pilot operating the latter.

Claim 4

A hydraulic control system for a vehicle of the type having implement actuator means and first and second bidirectional travel motors, each travel motor having a forward travel port for the reception of power fluid for rotation in a direction of forward vehicle travel and a rearward travel port for the reception of power fluid for rotation in a direction of rearward vehicle travel, the control system comprising: (a) first and second pumps for supplying power fluid; (b) a third pump for supplying pilot control fluid; (c) first pilot-operated implement valve means for controlling the delivery of the power fluid from the first pump to the implement actuator means; (d) second pilot-operated implement valve means for controlling the delivery of the power fluid from the second pump to the implement actuator means; (e) implement control valve means for pilot operating the first and second implement valve means by controlling the delivery of the pilot control fluid from the third pump thereto; (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 and being pilot actuated to open; and (i) straight travel control valve means responsive to the actuation of the first and second travel valves for delivering the pilot control fluid from the implement control valve means to a pilot port of the straight 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; (j) whereby the first and second travel motors when set into rotation in the same direction are powered by the combined power fluid from the first and second pumps if then at least either of the first and second implement valve means is being pilot actuated by the implement control valve means, thereby making possible the straight travel of the vehicle in either the forward or rearward direction; said straight travel control valve means comprising a first straight travel control valve normally blocking the pilot control fluid and allowing the pilot control fluid to pass therethrough upon actuation of one of the first and second travel valves in either direction; and a second 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.

Claim 5

A hydraulic control system for a vehicle of the type having implement actuator means and first and second bidirectional travel motors, each travel motor having a forward travel port for the reception of power fluid for rotation in a direction of forward vehicle travel and a rearward travel port for the reception of power fluid for rotation in a direction of rearward vehicle travel, the control system comprising: (a) first and second pumps for supplying power fluid; (b) a third pump for supplying pilot control fluid; (c) first pilot-operated implement valve means for controlling the delivery of the power fluid from the first pump to the implement actuator means; (d) second pilot-operated implement valve means for controlling the delivery of the power fluid from the second pump to the implement actuator means; (e) implement control valve means for pilot operating the first and second implement valve means by controlling the delivery of the pilot control fluid from the third pump thereto; (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 and being pilot actuated to open; and (i) straight travel control valve means responsive to the actuation of the first and second travel valves for delivering the pilot control fluid from the implement control valve means to a pilot port of the straight 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; (j) whereby the first and second travel motors when set into rotation in the same direction are powered by the combined power fluid from the first and second pumps if then at least either of the first and second implement valve means is being pilot actuated by the implement control valve means, thereby making possible the straight travel of the vehicle in either the forward or rearward direction; said straight travel control valve means comprising a first straight travel control valve normally blocking the pilot control fluid and allowing the pilot control fluid to pass therethrough upon actuation of one of the first and second travel valves in either direction; and a second 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.

Claim 6

The hydraulic control system of claim 3 wherein each of the first and second implement valve means comprises a parallel connection of implement valves, wherein the implement control valve means comprises a plurality of implement control valves for pilot operating the individual implement valves, and wherein the straight travel control valve means is connected to receive the pilot control fluid from the implement control valves via respective check valves, whereby the first and second travel motors when set into rotation in the same direction are powered by the combined power fluid from the first and second pumps if then at least one of the implement valves is being pilot actuated by one of the implement control valves.