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A dual steering system for use on a material handling vehicle having a chassis with front steerable wheels and an upperstructure movably supported from the chassis for rotary movement about a connecting center pin. The vehicle has a main truck cab on the chassis, from which the vehicle may be driven

A dual steering system for use on a material handling vehicle having a chassis with front steerable wheels and an upperstructure movably supported from the chassis for rotary movement about a connecting center pin. The vehicle has a main truck cab on the chassis, from which the vehicle may be driven over road to a selected site, and an operator cab on the upperstructure from which the excavator vehicle may be operated and also driven for short distances. When the vehicle is driven over road, the vehicle is steered from a steering wheel in the main truck cab, and hydraulic power is provided by a hydraulic power supply mounted on the chassis. When the excavator is controlled from the operator cab, the vehicle is steered with a joy stick and hydraulic power is supplied from an alternate hydraulic supply on the upperstructure. Thus, two alternate but interconnected sources of hydraulic fluid are utilized to provide power to a hydraulically powered, mechanically controlled steering gear. Operatively connected to the mechanical input of the chassis steering gear is the output of a tee gear box which has two rotary mechanical inputs for controlling the output. One rotary input to the tee gear box is from the steering wheel located in the main truck cab on the chassis. A second rotary input to the tee gear box is provided by a hydraulic torque motor which is controlled through the joy stick steering device in the operator cab on the upperstructure.

대표청구항 ▼

A material handling vehicle comprising: a power driven chassis having a main cab; front wheels on said chassis which are positionable to steer said driven chassis; an upperstructure supported by said chassis and being movable relative thereto having an operator cab; a center pin connecting said chas

A material handling vehicle comprising: a power driven chassis having a main cab; front wheels on said chassis which are positionable to steer said driven chassis; an upperstructure supported by said chassis and being movable relative thereto having an operator cab; a center pin connecting said chassis and said upperstructure; an upper hydraulic power supply disposed on said upperstructure providing an output of pressurized hydraulic fluid; a flow divider connected to the output of said upper hydraulic power supply to divide the output thereof into a control component output and a power component output; chassis steering means having a mechanical output, connected to said front wheels for steering said chassis, and a hydraulic input, which receives pressurized hydraulic fluid, and a mechanical input which controls the mechanical output for steering said chassis; a chassis power supply disposed on said chassis providing a second source of pressurized hydraulic fluid; first connecting means for connecting the power component output of said flow divider through said center pin to the hydraulic input of said chassis steering means; second connecting means for connecting the hydraulic output of said chassis power supply to the hydraulic input of said chassis steering means; a tee gear box having a mechanical output, connected to the mechanical input of said chassis steering mechanism, and first and second mechanical inputs; a torque motor disposed on said chassis having a mechanical output connected to the first mechanical input of said tee gear box; a positionable steering device located in the operator cab on said upperstructure; a steering valve operably connected to said steering device having a hydraulic connection to the control component output of said flow divider and providing an output in response to positioning of said steering device; third connecting means connecting the output of said steering valve through said center pin to said torque motor for positioning the torque motor in response to positioning of said steering device on said upperstructure; and, a steering wheel in the main cab on said chassis connected to the second mechanical input of said tee gear box.