Dual hydraulic power steering system
First Claim
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1. A hydraulic steering system for turning the steerable wheels of a vehicle, the system comprising:
- a first fluid motor having first and second chambers;
a second fluid motor having third and fourth chambers;
first and second control valves, each first and second control valve having an input port, a return port, and first and second motor ports, each first and second control valve having a first position wherein the input port is fluidly connected to the first motor port and the return port is fluidly connected to the second motor port and a second position wherein the input port is fluidly connected to the second motor port and the return port is fluidly connected to the first motor port;
a first directional valve having an input port, a first discharge port, and a second discharge port, the first directional valve having a first position wherein the input port is fluidly connected to the first discharge port and not to the second discharge port and a second position wherein the input port is fluidly connected to the second discharge port and not to the first discharge port;
a second directional valve having a first input port, a second input port, and a discharge port, the second directional valve having a first position wherein the first input port and not the second input port is fluidly connected to the discharge port and a second position wherein the second input port and not the first input port is fluidly connected to the discharge port;
a third directional valve having a first input port, a second input port, and a discharge port, the third directional valve having a first position wherein the first input port and not the second input port is fluidly connected to the discharge port and a second position wherein the second input port and not the first input port is fluidly connected to the discharge port;
a first flow conduit extending from the first discharge port of the first directional valve to the input port of the first control valve;
a second flow conduit extending from the second discharge port of the first directional valve to the input port of the second control valve;
a third flow conduit extending from the first motor port of the first control valve to the first input port of the second directional valve;
a fourth flow conduit extending from the first motor port of the second control valve to the second input port of the second directional valve;
a fifth flow conduit extending from the second motor port of the first control valve to the first input port of the third directional valve;
a sixth flow conduit extending from the second motor port of the second control valve to the second input port of the third directional valve;
a seventh flow conduit extending from the discharge port of the second directional valve to the second and fourth chambers; and
an eighth flow conduit extending from the discharge port of the third directional valve to the first and third chambers.
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Abstract
A hydraulic power steering system controllable by left and right steering wheels has two control valves, each valve connected to a respective left and right steering wheel, and a valve arrangement that selectively connects one control valve to a source of high-pressure fluid and disconnects the other control valve from the source of high-pressure fluid.
63 Citations
16 Claims
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1. A hydraulic steering system for turning the steerable wheels of a vehicle, the system comprising:
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a first fluid motor having first and second chambers; a second fluid motor having third and fourth chambers; first and second control valves, each first and second control valve having an input port, a return port, and first and second motor ports, each first and second control valve having a first position wherein the input port is fluidly connected to the first motor port and the return port is fluidly connected to the second motor port and a second position wherein the input port is fluidly connected to the second motor port and the return port is fluidly connected to the first motor port; a first directional valve having an input port, a first discharge port, and a second discharge port, the first directional valve having a first position wherein the input port is fluidly connected to the first discharge port and not to the second discharge port and a second position wherein the input port is fluidly connected to the second discharge port and not to the first discharge port; a second directional valve having a first input port, a second input port, and a discharge port, the second directional valve having a first position wherein the first input port and not the second input port is fluidly connected to the discharge port and a second position wherein the second input port and not the first input port is fluidly connected to the discharge port; a third directional valve having a first input port, a second input port, and a discharge port, the third directional valve having a first position wherein the first input port and not the second input port is fluidly connected to the discharge port and a second position wherein the second input port and not the first input port is fluidly connected to the discharge port; a first flow conduit extending from the first discharge port of the first directional valve to the input port of the first control valve; a second flow conduit extending from the second discharge port of the first directional valve to the input port of the second control valve; a third flow conduit extending from the first motor port of the first control valve to the first input port of the second directional valve; a fourth flow conduit extending from the first motor port of the second control valve to the second input port of the second directional valve; a fifth flow conduit extending from the second motor port of the first control valve to the first input port of the third directional valve; a sixth flow conduit extending from the second motor port of the second control valve to the second input port of the third directional valve; a seventh flow conduit extending from the discharge port of the second directional valve to the second and fourth chambers; and an eighth flow conduit extending from the discharge port of the third directional valve to the first and third chambers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A steerable vehicle comprising:
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one or more steerable wheels attached to a common steering linkage for simultaneous turning of the one or more steerable wheels to the left or right by actuation of the steering linkage; a source of high-pressure fluid; a first steering wheel, a second steering wheel, a first fluid motor having first and second motor chambers, a second fluid motor having first and second motor chambers, a first control valve, and a second control valve; the first steering wheel operatively connected to the first control valve, the second steering wheel operatively connected to the second control valve; each of the first and second fluid motors connected to the steering linkage and disposed to actuate said steering linkage, each of the first and second fluid motors disposed to independently actuate the steering linkage without operation of the other of the said first and second fluid motors; each of the first and second control valves comprising an input port fluidly connected to the source of high-pressure fluid, and first and second motor ports fluidly connected to respective first and second motor chambers of each of the first and second fluid motors; a first directional valve disposed between the source of high-pressure fluid and the first and second control valves, the first directional valve operable to selectively fluidly connect the input port of one of the first and second control valves with the source of high-pressure fluid and to fluidly disconnect the input port of the other of the first and second control valves from the source of high-pressure fluid; a second directional valve disposed between the control valves and the fluid motors and operable to selectively fluidly connect the motor ports of one of the first control valves with the fluid motors and to fluidly disconnect the motor ports of the other of the first and second control valves from the fluid motors. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification