Towmotor Corporation

Caterpillar Industrial Inc.

Wayne T Wiblin

Grant C Melocik

William Pickering

Edward V Leskovec

Bernard E Erlacher

Arthur Wild

Lancelot A Jobling

Gwenne A Henricks

Ronald D Surma

Norman H Palmer

An apparatus for dampening current in a coil has a switchable member which controls the current level in the coil and a flyback circuit that allows current in the coil to slowly dissipate when the switchable member changes from an 'ON' to an 'OFF' state. The flyback circuit has a high resistance when the switchable member changes from the 'ON' to the 'OFF' state so that the coil current is dampened as quickly as possible without creating a destructive voltage and low resistance when the switchable member is in the 'ON' state to conserve energy. A signaling device creates a voltage signal as a function of current passing through the flyback circuit and a receiving device varies the resistance of the flyback circuit in response to the voltage signal. The apparatus is particularly suited for use in a motor control circuit.

Flyback current dampening apparatus

An apparatus for controlling the supply of power to an electric drive motor normally controls the duty cycle of a power switching element to produce a variety of vehicle speeds. The apparatus typically controls the rate of change of the duty cycle to provide smooth vehicle operation. During periods of extended high speed, high load operation the apparatus bypasses the power switching element and connects the vehicle battery directly to the drive motor via a contactor. Under normal operating conditions the bypass contactor is energized after a relatively short preselected delay; however, where the vehicle is heavily loaded, such that current limiting of the power switching element exists, the apparatus interactively delays energization of the bypass contactor to allow the vehicle sufficient time to accelerate to a higher speed. Such a control system advantageously reduces drive line shock and jerky operation of the vehicle, as well as, excessive sparking at the contactor.

Apparatus for interactively accelerating an electric drive vehicle

Information related to the position of a control member of a vehicle is required for control of power delivered to the vehicle motors. Available linear position encoders are expensive and prone to damage in an industrial environment. The instant apparatus provides a simple and durable linear position encoder having a piston adapted to move within a housing. A plurality of sensors are each positioned along a different housing pathway and a plurality of sensible members are each positioned along a different piston pathway. In response to movement of the piston within the housing the sensors deliver respective position signals to an electric circuit means, which, in turn, delivers respective coded digital signals to a vehicle controller. The apparatus is digital in design and is of simple, rugged, and inexpensive construction.

Linear position encoder

Information related to the rotary angular position of a steerable wheel portion of an electric vehicle is required for proper control of the vehicle and especially for differential control of the driven wheels of the vehicle. Available rotary position encoders are expensive, prone to damage in an industrial environment, and sensitive to misalignment between the encoder components. The instant apparatus provides a simple and durable rotary position encoder having a plurality of sensors positioned on a first mounting member and a plurality of sensible members positioned on a second mounting member. The apparatus is digital in design and the particular location and arrangement of the sensors and sensible members advantageously compensates for overtravel and misalignment of the encoder components.

Angular rotary position encoder

Single pedal vehicle speed and direction controls are advantageously applied in industrial vehicles. Available pedals are prone to damage in an industrial environment and require multiple discrete pedal portions for various pedal functions. The instant apparatus provides a simple and durable foot pedal having a unitary pad including first and second integral moveable members and respective sealed switchable members. The pad is advantageously of one piece molded rubber construction and includes first and second resilient portions, each having a curvilinear connecting portion and an intermittent substantially solid connecting portion. The switchable members include respective sealed membrane switches, each having first and second spaced apart electrically conductive contact surfaces. At least one of the first and second conductive contact surfaces is attached to a flexible polymer film and is maintained separated from the other first and second conductive contact surfaces by a pressure medium contained within an enclosed pressurable chamber. The respective pressurable chambers are connected to one another and to a common pressure medium reservoir by respective interconnecting passageways. The instant apparatus is both durable and reliable when used in an industrial environment, and is of relatively simple and inexpensive construction.

Foot pedal switch

An apparatus (10) is provided for controllably operating at least one solenoid coil (12) in a battery operated system. The mean voltage applied to the coil (12) is controlled in response to at least the battery voltage, facilitating the use of various battery voltages with a single voltage coil (12). The apparatus (10) is readily adapted for controlling multiple coils (12) and is digital in design.

Voltage adaptive solenoid control apparatus

Magnetic control pedal apparatus

A standard hook-type carriage assembly designed for lift truck use in the handling of palletized cargo is converted for use in the handling of concrete blocks by hooking block-handling forks on the carriage plate and positioning such forks on the carriage plate with predetermined lateral spacings between the forks by a removable elongated spacer bar to which all of the forks are attached. Lost-motion connections are made between the forks and the spacer bar and limited lengthwise movement of the spacer bar relative to the carriage plate is permitted so that the forks can float, relative to each other and in unison, laterally along the carriage plate. The forks can also move independently of each other through a limited vertical distance relative to the carriage plate.

Hook-type carriage plate with floating forks

Magnetic control apparatus (32) for intensifying a magnetic field to actuate a magnetic control member (34) and for preventing simultaneous actuation of a pair (34, 36) of magnetic control members. In one (32) of several embodiments a pair (38, 40) of selectively movable magnets each respectively produces a magnetic field which, when a magnet is moved into position, is directed by a pair (42, 54) of elongated bars across the pair (34, 36) of control members to actuate one of the members in response to the field. The pair (42, 54) of bars bypass the magnetic fields from the control members (34, 36) when both magnets (38, 40) are in such a position to attempt to actuate the control members (34, 36). The pair (42, 54) of elongated bars intensify the magnetic fields at the control members (34, 36), thereby permitting the use of relatively weak magnets at a substantial distance from the members (34, 36). The pair (42, 54) of bars also provide a magnetic interlock, preventing undesirable simultaneous actuation of the members (34, 36). The apparatus (32) can be used on a pedal (100) of a fork lift truck to actuate one member (34) to shift a transmission into forward drive and to actuate the other member (36) to shift the transmission into reverse drive. Also disclosed is magnetic control apparatus (10) to perform only the function of field intensification.

Magnetic control apparatus

Lift truck instrument panel

An apparatus having an accelerator element has a potentiometer including an inner portion movable relative to an outer portion thereof in response to movement of the accelerator element. Adjusting and support members are interconnected for adjusting the outer potentiometer portion relative to the inner portion.

Adjustable potentiometer in an accelerator control

A method for assembling a lift truck mast having a slider element positioned within a channel element.

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Ashtabula, OH, United States of America

Wayne T Wiblin