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Going Remote Control in 1968
Slag removal from around steel mill furnaces has always been a hot, uncomfortable job for machine operators – and not without a certain amount of risk. Since the late 1960s, some steel mills attempted to protect the operator from discomfort and danger by experimenting with various systems of remote control for loaders and dozers. These systems met with limited success due partially to the high temperature of the material being handled and partially to the fragility of radio components.
The first breakthrough came in 1968 when a major steel producer, working through the local Caterpillar dealer, negotiated with Caterpillar to develop and build two radio remote-controlled Cat® 977K Track Loaders for slag removal. These units were delivered in early 1969 and proved to be capable and dependable. This initial success influenced the sale of a similarly equipped 955 and an order for a 983 Track Loader.
The project was coordinated internally at Caterpillar by engineering and purchasing employees in Peoria, Illinois. Barrett Electronics of Northbrook, Illinois, acted as developer and supplier of the radio components.
Machine Operation Controlled from a Safe Distance
The machine was controlled from a distance of up to one-quarter mile by means of a solid state, integrated circuit, transmitter and receiver. This radio contained 22 channels, each of which activated an individual machine control. Only 14 channels were required for machines in a slag removal application.
The lightweight battery-powered transmitter was fastened to a shoulder harness worn by the operator. The sending antenna was built into the harness. Small lever-switches on the transmitter panel duplicated the controls of the Cat Track Loader and, within a short time, an operator could easily adapt himself to the remote control.
Two whip antennas, mounted on the machine, picked up radio signals for the toolbox-sized receiver located in a protected area. The receiver decoded the signal to provide an electrical impulse for the proper function.
The interface section, which converted electrical impulses to control forces, was developed by Caterpillar. The actual force for moving the various control levers was supplied by a low pressure hydraulic system filtered with a 10-micron filter.
If any malfunction occurred in the remote-control system, or if the operator fell, the machine automatically assumed a “safe condition” consisting of a neutral transmission, a bucket hold, locked brakes and the engine at low idle.
Light signals and visual magnetic indicators were mounted on the fuel tank to inform the operator of important temperature and pressure conditions within the machine.
The modified machine could be quickly converted to manual operation by opening a small valve and removing pins on the control levers.
Today’s Remote-Controlled and Autonomous Systems
As a global leader, we strive to offer not only great products, but also solutions beyond the iron – the technology, data analytics and automation our customers expect and need. The success of the control system developed in the 1960s led to other applications today where environmental conditions near the machine are uncomfortable or hazardous. For example, mining customers today can use Cat Command for Dozing to increase their productivity and reduce costs – while, most importantly, keeping operators out of harm’s way.