Caterpillar Industrial Inc.

Bruce A Nielsen

William Pickering

Arthur Wild

Motor control systems having direction contacts for steering current through a motor are commonly associated with electrical industrial vehicles, such as lift trucks. Advantageously, the operation of the direction contacts should be optimized in order to prevent switching the contacts when current is present to the extent that such switching can be eliminated. The instant apparatus includes a logic device for receiving speed and direction demand signals and responsively controlling the direction contacts associated with a vehicle motor. The logic device also receives signals from a current sensor responsive to the magnitude of electrical current flowing through the electric motor. In response to the motor current signal indicating a value less than a predetermined value concurrent with either the motor direction demand signal having a neutral value or the motor speed demand signal having a zero value, the logic means produces a neutral motor direction command signal. Therefore, optimal control of the motor direction contacts is attained.

Motor direction contactor switching control

An apparatus for controlling a load lifting implement of a work vehicle in response to the condition of a motor brush is provided. The vehicle has a frame and the load lifting implement is connected to the frame and elevationally moveable relative to the frame between first and second directions. A brush wear indicator senses the wear of the motor brush and produces a warning signal in response to a predetermined amount of wear of the motor brush. A control system receives the warning signal and responsively controllably inhibits the elevational movement of the load lifting implement in at least one of the first and second directions.

Apparatus for controlling a load lifting element of a vehicle in

A motor speed control system for a vehicle is provided. The control system includes an electric motor connected to a power coupling element for delivering electrical energy to the motor in response to a control signal. A sensor produces a current signal in response to the magnitude of the current flowing through the motor. An accelerator pedal produces a command signal in response to a desired vehicle speed. A microprocessor receives the command signal and responsively delivers a pulse width modulated control signal to the power coupling element. The control signal has a duty cycle in a range between a minimum and predefined value. Additionally, the microprocessor receives the current signal and increases the duty cycle of the control signal by a predetermined amount beyond the predefined value in response to the received current signal.

Growing community of inventors

Painesville, OH, United States of America

Bruce A Nielsen