Steering system

Claim 2

In a vehicle having a pair of engines and a pair of steerable axles including at least one power steering ram on each, the improvement comprising: first and second pumps driven by one engine; third and fourth pumps driven by the other engine; said first and third pumps being connected to supply fluid pressure for the power steering ram on one axle; and said second and fourth pumps being connected to supply fluid pressure for the power steering ram on the other axle; whereby both axles are steerable when either one of the engines is operating.

Claim 3

The invention according to claim 1, and further comprising: first check valve means for precluding flow between the first and third pumps; and second check valve means for precluding flow between said second and fourth pumps.

Claim 4

The invention according to claim 2, and further comprising: first directional flow control valve means for directing fluid from said first and third pumps to a selected end of the steering ram on said one axle; and second directional flow control valve means for directing fluid from said second and fourth pumps to a selected end of the steering ram on the other axle.

Claim 5

The invention according to claim 3, and further comprising: a first sensing cylinder connected to and capable of shifting said first valve means; a second sensing cylinder connected to and capable of shifting said second valve means.

Claim 6

A selectable mode steering system for a vehicle having a pair of steerable axles, comprising: a first hand pump capable of manipulation by an operator; a directional flow control valve including hydraulic actuators communicating with the hand pump; a pilot pump communicating with said flow control valve; a first sensing cylinder connected to one axle and having each end in communication with said flow control valve; a first main power steering valve operably connected to the first sensing cylinder; first steering ram means having each end in communication with the first main power steering valve and operably connected to said one axle; a mode control valve communicating with said flow control valve; a second sensing cylinder operably connected to the other axle and having each end in communication with the mode control valve; a second main power steering valve operably connected to the second sensing cylinder; second steering ram means having each end in communication with the second main power steering valve and operably connected to said other axle; a mode control cylinder connected to said mode control valve; and a mode selector valve for directing fluid pressure to the mode control cylinder.

Claim 7

A selectable mode steering system for a vehicle having a pair of steerable axles, comprising: a first hand pump capable of manipulation by an operator; a directional flow control valve including hydraulic actuators communicating with the hand pump; a pilot pump communicating with said flow control valve; a first sensing cylinder connected to one axle and having each end in communication with said flow control valve; a first main power steering valve operably connected to the first sensing cylinder; first steering ram means having each end in communication with the first main power steering valve and operably connected to said one axle; a mode control valve communicating with said flow control valve; a second sensing cylinder operably connected to the other axle and having each end in communication with the mode control valve; a second main power steering valve operably connected to the second sensing cylinder; second steering ram means having each end in communication with the second main power steering valve and operably connected to said other axle; a mode control cylinder connected to said mode control valve; and a mode selector valve for directing fluid pressure to the mode control cylinder.

Claim 8

The invention according to claim 5, and further comprising: a second hand pump capable of manipulation by an operator; hand pump selector valve means for selectively communicating one of said first and second hand pumps with said flow control valve; position cylinder means operatively connected with the hand pump selector valve means; and a station selector valve for directing fluid pressure to or blocking fluid pressure from the position cylinder means in order to select one of the two hand pumps.

Claim 9

The invention according to claim 6, and further comprising: a second mode control valve interposed between said first sensing cylinder and said flow control valve; a second mode control cylinder operatively connected to said second mode control valve; and a second mode selector valve for directing fluid pressure to the second mode control cylinder.

Claim 10

The invention according to claim 7, wherein, said station selector valve selectively directs fluid pressure to one of said mode selector valve.

Claim 11

A selectable mode steering system for a vehicle having a pair of steerable axles, comprising: a first steering ram connected to one of the axles for power steering thereof; a first main power steering valve in fluid communication with each end of the first steering ram; a first sensing cylinder connected to said one axle and to the first main power steering valve to control the position thereof; a second steering ram connected to the other of said axles for power steering thereof; a second main power steering valve in fluid communication with each end of the second steering ram; a second sensing cylinder connected to said other axle and to the second main power steering valve to control the position thereof; pump means in fluid communication with the first and second power steering valves; mode control valve means in fluid communication with each end of the first and second sensing cylinders; and selector means to selectively position said mode control valve means to provide a plurality of modes of power steering for the vehicle.

Claim 12

A selectable mode steering system for a vehicle having a pair of steerable axles, comprising: a first steering ram connected to one of the axles for power steering thereof; a first main power steering valve in fluid communication with each end of the first steering ram; a first sensing cylinder connected to said one axle and to the first main power steering valve to control the position thereof; a second steering ram connected to the other of said axles for power steering thereof; a second main power steering valve in fluid communication with each end of the second steering ram; a second sensing cylinder connected to said other axle and to the second main power steering valve to control the position thereof; pump means in fluid communication with the first and second power steering valves; mode control valve means in fluid communication with each end of the first and second sensing cylinders; and selector means to selectively position said mode control valve means to provide a plurality of modes of power steering for the vehicle.

Claim 13

The invention according to claim 9, and further comprising; a first operator station on the vehicle; a first hand control pump, capable of manipulation by an operator, located in said first station; said first hand pump being arranged to control the flow of hydraulic fluid to said mode control valve means.

Claim 14

The invention according to claim 10, and further comprising: a second operator station on the vehicle remote from said first station; a second hand control pump, capable of manipulation by an operator, located in said second station; said second hand pump being arranged to control the flow of hydraulic fluid to said mode control valve means; and station selector means located in at least one of said stations and capable of selectively rendering one of said hand pumps inoperative.

Claim 15

A selectable mode steering system for a vehicle having a pair of steerable axles, comprising: a first hydrostatic hand pump capable of manipulation by an operator; a power pump in communication with said first hand pump and capable of supplying hydraulic fluid under pressure thereto; first and second mode control valves in communication with said hand pump; first and second sensing cylinders connected respectively with opposite axles and having each end in fluid connection with the first and second mode control valves respectively; first and second main power steering valves connected to one end of said first and second sensing cylinders respectively; first and second steering rams connected to opposite axles for power steering thereof and being in fluid communication with said first and second steering valves respectively; pump means for supplying hydraulic fluid to said first and second steering valves; electrical solenoid means associated with said mode control valves; and first mode switch means for selectively energizing said solenoid means.

Claim 16

A selectable mode steering system for a vehicle having a pair of steerable axles, comprising: a first hydrostatic hand pump capable of manipulation by an operator; a power pump in communication with said first hand pump and capable of supplying hydraulic fluid under pressure thereto; first and second mode control valves in communication with said hand pump; first and second sensing cylinders connected respectively with opposite axles and having each end in fluid connection with the first and second mode control valves respectively; first and second main power steering valves connected to one end of said first and second sensing cylinders respectively; first and second steering rams connected to opposite axles for power steering thereof and being in fluid communication with said first and second steering valves respectively; pump means for supplying hydraulic fluid to said first and second steering valves; electrical solenoid means associated with said mode control valves; and first mode switch means for selectively energizing said solenoid means.

Claim 17

The invention according to claim 12, and further comprising: a second hydrostatic hand pump capable of manipulation by an operator; a power pump valve for connecting the power pump with one of said hand pumps while simultaneously isolating the other therefrom; a steering pump valve for establishing connection between said mode control valves and one of said hand pump while simultaneously isolating the other.

Claim 18

The invention according to claim 13, wherein said power pump valve and said steering pump valve are solenoid actuated.

Claim 19

The invention according to claim 14, and further comprising: a station selector switch for simultaneously energizing and de-energizing said solenoid actuated power and steering pump valves.

Claim 20

The invention according to claim 15, and further comprising: second mode switch means for selectively energizing said solenoid means of said mode control valves; said second mode switch means being rendered inoperative and said first switch means rendered operative when said solenoid actuated power and steering pump valves are de-energized and said first mode switch means being rendered inoperative and said second switch means rendered operative when said solenoid actuated power and steering pump valves are energized.