US 4,307,300 A · Dump truck with safety circuit

Abstract

An electrical circuit for driving an electrically driven vehicle such as a dump truck is capable of preventing occurrence of accidents caused by an erroneous operation and thereby increasing safety by providing an arrangement such that the vehicle cannot start unless all necessary operations have been completed before starting. For this purpose, a power source of a control box controlling an exciting current for a generator is turned on to generate the exciting current only when all necessary operations have been completed. This is achieved by connecting a plurality of switches corresponding to various operations in series to a power source relay and thereby causing the power source relay to be actuated upon closing of all of these switches. The circuit also enables the motors to be utilized as generators to provide dynamic braking for the truck.

Claims6

Dependent claims

A circuit for a dump truck which is driven by at least one electric motor which is powered by a generator, said dump truck having a brake pedal or the like, a dumping mechanism and a dump control lever or the like, comprising:

a control circuit for providing a control current to the generator, said control circuit including a first safety switch which is activated to interrupt the control current upon the application of the brake pedal;
at least one switch for connecting the electric motor as a generator to provide dynamic braking, said at least one switch being activated upon the application of the brake pedal;
and
a second safety switch in said control circuit, connected to the dumping mechanism or dump control lever, which is activated to interrupt the control current when a dumping operation is being performed, activation of said second safety switch preventing powering of the motor by the generator, thereby preventing accidental movement of the truck during dumping whether or not the brake pedal is applied.

1 more element

A safety interlock circuit for use in a dump truck which is electrically driven by means of at least one electric motor, comprising:

a generator for driving the electric motor;
a diesel engine for driving the generator;
an exciter for controlling the generator;
an exciter control circuit for providing a controlling current to the exciter, said control circuit including a power source relay, a power source connected via the power source relay to provide exciting current for the generator, and a plurality of safety interlock switches connected in series between the power source relay and the power source, the opening of any of the switches preventing the generation of the exciting current, said switches including:
a starting switch which is closed upon the starting of the diesel engine;
a dump control switch which is closed when the dump truck is not performing a dumping function;
an engine idle switch which is closed when the diesel engine reaches a predetermined revolution rate;
a parking brake switch which is closed when a parking brake in the dump truck is released;
and a standard brake switch which is closed upon the release of a brake pedal or the like;
a plurality of motor contactors which are closed upon the pressing of an accelerator pedal or the like to couple the motors to the generator;
a plurality of brake resistors;
a blower for cooling the brake resistors;
and
a plurality of brake contactors which are closed upon the application of the brake pedal to connect the motors to the brake resistors, the motors thereby acting as generators and enabling kinetic energy of the truck to be dissipated in the resistors.

11 more elements

Dependencies are inferred from the claim text.

Dump truck with safety circuit

Life of this patent

Dump truck with safety circuit

Life of this patent

Abstract

Claims6