Hydraulically actuated flanged guide wheels of a convertible rail-highway vehicle

Claim 1

An engine-driven highway-railway vehicle having front and rear pneumatic wheels and retractable guide wheels assemblies, the front assembly being adapted, when lowered, to engage the rails of a track and to lift the pneumatic wheels therefrom, the rear assembly being adapted to engage the rails of the track and to share the load with the rear pneumatic wheels which remain in contact with the rails to provide a driving and braking force, said assemblies including oil-operated hydraulic actuators to raise and lower said guide wheels and a hydraulic circuit for operating said actuators, said actuators discharging oil when energized by incoming oil to raise or lower the guide wheels, said circuit comprising: A. a pressurized oil accumulator, B. a nonpressurized oil reservoir, C. conduit means having control valves interposed therein for conducting oil from said accumulator to said actuators in a selected direction to cause said actuators to raise or lower the guide wheels associated therewith, said conduit means also conducting oil discharged by said accumulators to said reservoir said control valves being always open, whereby pressure surges within the actuators create a back flow of oil into the accumulator, D. conduit means having a pump interposed therein for coupling said reservoir to said accumulator to feed oil taken from said reservoir into said accumulator, E. normally open switch means operatively coupled to said accumulator to sense oil pressure within said accumulator to cause closure of said switch when this pressure falls below a predetermined level, and F. motor means responsive to said switch closure and operatively coupled to said pump to drive said pump until the pressure in said accumulator attains said predetermined level, at which point said switch is reopened to stop said pump, thereby maintaining a substantially constant pressure in said hydraulic actuators.