The Paul Revere Corporation

Dale Baldauf

Larry J Pingry

The steerable wheels of a hydraulically driven vehicle are provided with fixed displacement type auxiliary motors which are connected in parallel both with each other and with the motor which powers the main drive wheels. A selector valve permits the motors for the steerable wheels to be optionally connected and disconnected from the reversible, variable displacement main pump. Flow dividers in the hydraulic lines limit the maximum flow of fluid to any one auxiliary drive motor. To prevent large power losses when the steerable wheel assist mode is not being utilized, the selector valves are placed in close proximity to each fixed displacement motor. This allows the motors to circulate large quantities of fluid around a closed loop at minimum pressure drop.

Auxiliary hydrostatic drive system

The steerable wheels of a hydraulically driven vehicle are provided with auxiliary motors which are connected in parallel both with each other and with the motor which powers the main drive wheels. A selector valve permits the motors for the steerable wheels to be optionally connected and disconnected from the reversible, variable displacement main pump. Flow dividers in the hydraulic lines limit the maximum flow of fluid to any one hydraulic motor. The auxiliary motors are of the variable displacement type, enabling them to be destroked to neutral when disconnected from the main pump. Destroking to neutral eliminates energy loss due to the pumping of large quantities of hydraulic fluid through a closed loop when the motors are driven by the wheels.

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Coldwater, OH, United States of America

Dale Baldauf