Hydraulic differential speed steering system

Claim 1

A STEERING SYSTEM FOR A VEHICLE HAVING PROPELLING TRACKS AT OPPOSITE SIDES THEREOF MOVABLE AT DIFFERENT SPEEDS FOR PURPOSES OF STEERING, COMPRISING, A PAIR OF DRIVE SHAFTS RESPECTIVELY AT OPPOSITE SIDES OF THE VEHICLE FOR CONNECTION RESPECTIVELY WITH THE VEHICLE TRACKS, A PAIR OF VARIABLE DISPLACEMENT HYDRAULIC MOTORS RESPECTIVELY CONNECTED FOR DRIVING THE DRIVE SHAFTS, SEPARATE FLUID OPERATED MEANS RESPECTIVELY CONNECTED FOR VARYING THE DISPLACEMENT OF THE MOTORS AND THEREBY VARYING THE SPEED OF THE MOTORS, A MANUALLY OPERABLE STEERING CONTROL MOVABLE IN OPPOSITE DIRECTIONS FROM A NEUTRAL CENTER POSITION FOR STEERING THE VEHICLE IN OPPOSITE DIRECTIONS, CONTROL VALVE MEANS YIELDABLY CONNECTED TO SAID STEERING CONTROL FOR OPERATING SAID DISPLACEMENT VARYING MEANS TO VARY THE RELATIVE SPEEDS OF THE MOTORS AS DICTATED BY MOVEMENT OF THE STEERING CONTROL, A DIFFERENTIAL HAVING INPUTS DRIVEN BY THE DRIVE SHAFTS AND AN OUTPUT ROTATABLE IN A DIRECTION AND AT A SPEED INDICATIVE OF THE DIFFERENCE IN SPEEDS OF THE DRIVE SHAFTS, AND PUMP MEANS DRIVEN BY THE DIFFERENTIAL OUTPUT AND CONNECTED FOR DELIVERING FLUID TO SAID VALVE MEANS IN OPPOSITION TO SAID MANUALLY OPERABLE STEERING CONTROL FOR NEUTRALIZING THE CONTROL VALVE MEANS WHEN THE DICTATED RELATIVE SPEEDS ARE OBTAINED.