초록 ▼

A hydrostatic propulsion system and method of operation is disclosed for smoothly driving a vehicle, such as a street sweeper. The system includes a shift lever for selectively moving a pump stroking valve into reverse, neutral, low forward, and fast forward speed positions to prepare the system. Af

A hydrostatic propulsion system and method of operation is disclosed for smoothly driving a vehicle, such as a street sweeper. The system includes a shift lever for selectively moving a pump stroking valve into reverse, neutral, low forward, and fast forward speed positions to prepare the system. After the shift lever has been placed in a forward or reverse position, an accelerator pedal must be depressed to partially or fully close an inching throttle valve before the pump swash plate moves from its zero piston displacement position and begins to pump fluid to the hydrostatic motors. Hydrostatic braking forces are applied when the accelerator pedal is released and also in response to initial depression of a brake pedal for providing normal braking to the vehicle. Further depression of the brake pedal operates a conventional brake system for panic stops. Movement into the high forward speed range is accomplished by moving the shift lever into “high”which activates a circuit for shifting the swash plates of the hydrostatic motors into high speed positions.

대표청구항 ▼

A hydrostatic propulsion system for a vehicle such as a mobile sweeper or the like having driven wheels, comprising: means defining a main power driven positive displacement swash plate pump including pistons and having forward and reverse pump stroking means for varying the position of the swash pl

A hydrostatic propulsion system for a vehicle such as a mobile sweeper or the like having driven wheels, comprising: means defining a main power driven positive displacement swash plate pump including pistons and having forward and reverse pump stroking means for varying the position of the swash plate between zero piston displacement to full forward or full reverse piston displacement; means defining at least one swash plate motor operatively connected to said pump and to at least one driven wheel and having low speed and high speed motor stroking means for varying the position of the motor swash plate betwewen an initial high piston displacement low speed position and a low piston displacement high speed position; means defining a pump stroking valve; means for providing and maintaining hydraulic fluid in said main pump and in said motor; operator controlled shift means for moving said stroking valve between a neutral position and at least one pump selected operative position; inching throttle valve means movable between a fully open position and a fully closed position and in fluid communication with both of said pump stroking means and said stroking valve; operator controlled accelerator means for moving said throttle valve means between a fully open position and said fully closed position for progressively moving said pump stroking means between zero piston displacement and a positive piston displacement when said pump stroking valve is in said selected operative position for driving the vehicle in the selected direction; a hydrostatic brake valve connected in parallel with said inching valve and movable between a normal fully closed position and an open position, and a manually operated brake pedal operatively connected to said brake valve for shifting the valve to said open position upon initial movement of said pedal for balancing the fluid pressure acting on both of said pump stroking means for providing a hydrostatic braking force to the vehicle.