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January 2014

Remote Control of Lifts

Modern communications have made remote operation of lifts much easier. But that's no excuse for taking it for granted.

Written by Jim Ellis, P.E | 0 comment


Operating a chairlift has become a much simpler task since the first lifts were invented in the early 1930s. But that doesn’t mean operators can run their machines without a care in the world. Despite all our advances, there’s no way to get around Murphy’s Law: Things can always go wrong, and when you least expect it.

The earliest rope tows were developed in the eastern U.S. They consisted of a farm tractor converted to a stationary engine located at the top of the ski hill, driving a rope strung around a pulley at the bottom of the hill and looped around one of the tractor’s drive wheels. The “operator” was close by the engine, and the ignition of the gas engine was run a short distance to the “safety gate,” now known as the “stop gate.” That was the sole means of stopping the lift. If extending the ignition circuit to the bottom of the lift for remote stopping was ever tried, that evolutionary step has been lost to time. It is highly doubtful that it was tried, and even if it was, the results would have surely been poor—that circuit was never intended to see the line loss of perhaps 1,000 feet of wire or more.

In the West, a fellow named Jim Parker was aware of what was going on in the East and was encouraged to get tows operating in the local Cascades. Two other people, Bruce Kehr and Don Adams were also inspired in these efforts. With Don’s outgoing sales personality and Bruce’s technical and electrical ability, they soon had tows working in most of the ski areas in Washington.

The desire to locate the driving device at the bottom of the hill challenged Bruce, and he soon came up with a relay control system that allowed the “engine” (prime mover) to be run and stopped remotely from the top “safety gate.” Later models allowed the engine to be started remotely also. Early designs also allowed the start to override the stop, thereby allowing the “operator” at the lower terminal to manually override the system and permit an employee to ride up to the safety gate to reset it. This system of start overriding stop (jog) would be frowned on in future developments, though.

Most of the early tows and lifts were powered by internal combustion engines (gasoline), as electricity had not yet reached most remote mountain areas. The early lifts had an “operator” and only he had control of the starting of the lift, and usually its speed control (if any) as well.

Most of the early lifts had a “closed” stop circuit and, as such, the lift could be stopped from the end remote from the drive.

Operating these early lifts took a fair amount of skill. Starting a lift in those days might include a sequence like this: 1) Set the “emergency” brake (often the only brake on the lift). 2) Disengage the clutch. 3) Engage the ignition (stop circuit). 4) Reset the throttle control. 5) Start the engine and adjust the rpm. 6) While feathering the clutch, simultaneously release the brake, and with luck the lift would begin to move. 7) Adjust the throttle for the proper speed, and all is again operational.

Chairlifts brought more challenges, and with them, more ingenious solutions. For example, service was required on towers often. The quandary was how to be able to remotely operate the lift from almost anywhere along the line. Remember, reliable light radios had not yet arrived, so communication with the lift operator was often impossible.

It was here that Bruce Kehr again showed his genius. The solution, which lasted on many lifts into the 1960s, was to use an open stop circuit. This was a system that required closing a circuit to initiate a stop, rather than the more common closed circuit, where the open circuit stops the lift. So all controls on the lift were open circuit except the phone line. These circuits were also “made” (energized) by contact with ground (electrical ground). cont.

The controls available were: stop, start, slow and fast. The electrical lines consisted of galvanized bare #9 wires (telephone wire in those days). The wires were run in the open on glass insulators on top of the towers. The cable (traction rope) was securely grounded with an additional metal (and noisy) sheave for our remote (along the line) control.

So here’s how remote operation in this scenario works: An alligator clip is securely fastened to the chair of the person who will have the control. Connected to this clip is a short flexible wire that is, in turn, connected to an aluminum pole (called the wand). With everything in order, our “remote operator” deftly reaches out with his wand and contacts the start wire. If he is lucky, he can see the drive and thus see blue exhaust issuing from the exhaust stack—often, the prime mover in those days was a diesel engine with a fluid coupling or torque converter.

With step one complete, he can now reach out and contact the “fast” wire with the wand, and like magic, the lift begins to move. Speed is controlled by contacting the “slow” and “fast” wires as needed. As the remote operator approaches the target tower, he contacts the “slow” wire. Then, at the correct moment, he contacts the stop wire, and we are there to service the tower, and no one else has run the lift.

The “standard” that was developed in the late ’50s and printed in 1960 as the ASA B-77.1 standard required a closed circuit for the stop. But time marches on, and additional controls were added. In 1970 the ANSI B 77.1 Standard required manually reset stop switches, and the stop circuit was required to be “fail safe ground.” This requirement was often interpreted to mean “fail with a ground,” and that was not the intent, as the resistance to ground was not defined. The intent was that “any” ground would not impair the circuit function.

The 1973 Standard brought the requirement that “all structures” be grounded (that is another story). The 1976 B 77.1 Standard further specified that the control circuits all be energized circuits, the failure of which (open) or (power failure) would cause the lift to be inoperative. These were put into the standard for increased safety. After 1976, the B-77.1 Standard included emergency stops (emergency shutdown) after it was learned that lifts occasionally failed to respond to a bona fide stop command.

The remote control of lifts in 2013 is now most frequently accomplished with verbal commands through a two-way radio, and there’s less need for remote stop and start circuits. This system is not “fail safe,” however, especially if the radio is not turned on or the batteries are dead. Both of these events have occurred with various (bad) results. The lesson is, be careful! Radios often work very reliably until you really need them. That’s just the way Murphy’s Law always seems to work.