Lift truck drive train
AssigneeBiomet-Ross, Inc.
InventorFrank E. Steele
Life of this patent
Estimating the term…
Abstract
A lift truck having a parallel pair of drive trains, each powering a drive wheel on a different side of the lift truck. Each drive train includes a DC electric motor driving a variable displacement, hydraulic pump having a pressure output capacity of at least 3,000 psi. Each hydraulic pump is connected to a hydraulic motor, having a rotational speed capacity of at least 3,000 rpm and is connected through a transmission to the drive wheel on a different side of the lift truck. The DC motor is run continuously at full rpm and the torque/speed ratio of the drive train is controlled by controlling the displacement of the hydraulic pump.
Claims12
A lift truck having a power train drivingly linked to drive wheels of the lift truck, the power train including:
- (a) an electric motor;
- (b) a displacement hydraulic pump drivingly linked to the electric motor and having a pressure output capacity of at least substantially 3000 psi;
- (c) a displacement hydraulic motor connected by hydraulic conduit to receive hydraulic fluid from the pump and having a rotational speed capacity of at least substantially 3000 rpm, the pump, hydraulic motor and conduit forming a hydraulic circuit;
- and
- (d) a hydraulic fluid volumetric flow rate control connected in the hydraulic circuit for controllably varying the hydraulic motor torque and speed.
A method for propelling a lift truck having a battery driven electric motor, the method comprising:
- (a) driving a hydraulic pump at a hydraulic fluid pressure of at least 3000 psi with the electric motor;
- (b) driving a hydraulic motor at a rotational speed of at least 3000 rpm by applying hydraulic fluid from the pump to the hydraulic motor, the hydraulic motor being drivingly connected in a drive train connected to at least one wheel of the lift truck;
- and
- (c) varying the hydraulic fluid flow rate through the hydraulic motor to controllably vary the torque and speed ratio of the drive train.
Dependencies are inferred from the claim text.