Clark Equipment Compnay

Donald L Schultz

Louis A Haddock

An operating control system for a lift truck controlled from a single multi-function operator hand control which is located and designed for improved operator comfort, convenience, simplicity and to reduce operator fatigue. The sole hand control for directional and speed control and the operation of all hydraulic functions of the truck related to the handling of loads is recessed in a compartment adjacent one side of the truck and supported from a control shaft which extends forwardly, leftwardly and downwardly and along which the control handle may be pushed or pulled linearly to control all such hydraulic truck functions. The grip handle is rotatable to control direction and speed of the truck. Switch controls are located conveniently adjacent the one end of the rotatable grip handle for selecting a variety of hydraulic functions by the same movements forwardly and rearwardly of the operator control handle along the control shaft. Electrical and hydraulic systems control the various hydraulic functions and are operatively connected to the control handle for operator selection of direction and speed of the truck as well as simultaneous operation of any selected hydraulic function one at a time only.

Operator control system

A lift truck of the order-picker type is provided with an automatic control system for safe-guarding the operation against certain conditions. The electronic control system is responsive to an electrical height signal corresponding to the height of the lift fork to regulate or limit the other operational functions of the truck. The speed control channel compares the speed signal with a speed command signal and produces a speed control signal of limiting value. A travel interrupt channel compares the height signal with the steering angle and interrupts the vehicle travel if the steering angle is excessive. Usually, the high speed lift is cut-off when a predetermined height is reached; the lowering of the upright is disabled at a predetermined lower limit subject to manual override.

Travel/lift inhibit control

A lift truck in which a steering column or pylon houses a steering post connected to a hydraulic steering component. A locking device which is manually operable by the operator is adapted to lock the steering column in an operative driving position, the steering column being adapted to be actuated forwardly in a pivotal motion to a non-operative position by a gas pressure spring when the locking device is released by the operator, thus moving it to a forward position wherein it provides an improved access path to the operator's compartment and wherein it does not obstruct the vertical path of movement of a drive component when the latter is deposited in or removed from its generally central mounting position in the lift truck.

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Richland, MI, United States of America

Donald L Schultz