ApplicationNo. 06/096490 filed on 11/21/1979
US Classes:14/71.5, Attached to fixed structure at first end and with cover and provision to fit vehicle at second end180/6.48, Independently operable drive motors318/68Relative motor speed control
ExaminersPrimary: Byers, Nile C. Jr.
Attorney, Agent or Firm
International ClassesB64F 1/305 (20060101)
B64F 1/00 (20060101)
AbstractConveyance loading ramp has its inner end pivotally supported adjacent a building structure and the other end mounted on a mobile undercarriage having a pair of ground engaging wheels mounted one on each side of the ramp for rotation about a common horizontal axis. The undercarriage is supported for pivotal movement about a vertical axis for steering and an improved hydraulic driving and steering system includes separate hydraulic motor connected in series to drive the wheels. A first reversible variable flow control valve connected in the hydraulic circuit is operable to control both the rate and direction of flow of hydraulic fluid to the series connected motors and a second reversible variable flow valve connected in the circuit between the first valve and the hydraulic motors is operable to bypass one only of the hydraulic motors with a portion of hydraulic fluid from the first valve whereby the series connected hydraulic motors can be driven at different rates to steer the outer end of the ramp during expansion and retraction movement. A single manually actuated control connected to the first and second valves simultaneously controls both steering of the undercarriage and the direction and rate of movement of the drive motors.
Field of SearchAttached