From the Field: Operator Presence System Sometimes Tricky on Older Walk-Behind Trenchers

Brent Younker, president at Total Rental in the Portland, WA area, says he's had trouble with the operator presence system on some of the older models of walk-behind trenchers he has in his fleet.

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Here's the problem

Brent Younker, president at Total Rental in the Portland, WA area, says he's had trouble with the operator presence system on some of the older models of walk-behind trenchers he has in his fleet.

“The operator presence systems use an electronic module and receive info from the different controls by means of micro-switches and wires to tell the module if the operator was present or not, or if that control was in neutral so it could start the engine. The modules would go bad and switches would break, get out of adjustment, freeze, get dirty… Then we could not even start the engine, and it took a while to figure out which switch it was.”

Solutions vary

Manufacturers of today's walk-behind trencher models have worked to alleviate this problem through a variety of methods. Some continue to use electronic switches, but have improved their system by beefing up componentry and its protection within the unit.

"Electronics and electronic modules in trenchers have improved greatly over the years — both in reliability and capabilities — which improve operator presence systems," says Jon Kuyers at Vermeer Corp. "Safety and micro switches also have evolved over time to meet the demanding duty cycles in the construction industry.

"The switches on a walk-behind trencher today can resist contaminants and moisture much better, which caused premature failure in the past. The control modules themselves are also more industrial strength and provide greater capabilities, such as utilizing lights or symbols to identify controls or levers that are out of neutral, which did not allow the operators to start the machine. Some of the more advanced modules can also be utilized to troubleshoot maintenance issues in some cases, as well as diagnose the problem much faster," Kuyers says.

Other manufacturers have opted for moving away from an electronic operator presence system altogether in favor of a mechanical design.

"The more electrical components you have, the more chance you have of something going wrong," says Matt Collins at Ditch Witch. "In rental, reliability is crucial, so whenever possible, we keep it in steel, and keep it mechanical."

Ditch Witch made the switch back to a mechanical operator presence system in 2007 with the introduction of its RT10 walk-behind model. While the company has returned to mechanics in this case, when it comes to the trencher's drive system, Ditch Witch has actually moved away from mechanical components in favor of hydraulics. Ultimately, models are constantly changing and evolving in all areas to meet customers' needs. 

"At the end of the day, we're doing our best to improve reliability for our customers," Collins says. "Manufacturers always have to walk a fine line between sophistication and reliability."

At Barreto Mfg. Inc., the operator presence system has always been mechanical. 

"We do not use micro-switches on any Barreto equipment. We never have – on our older equipment or on our new equipment," says Jackie Leonard at Barreto. "Micro switches do tend to be a common maintenance item and when we produced our first trencher in 1995, we wanted to provide a solution by having a mechanical answer to operator presence rather than electrical."

She continues, "The clutch lever we use to engage our hydraulics is our operator presence control. If the operator lets go of that lever for any reason, the wheels and trenching chain stop, but the engine continues to run, eliminating the need to restart the machine to resume trenching."

Older models still in fleet?

If you own some older walk-behind trenchers and are experiencing issues with the operator presence system, you might still have options.

"On old model trenchers, rental owners should make sure that the machine has the most up-to-date or improved switch for the application," Kuyers says. "Many manufacturers will continue to support their equipment and make improvements in these areas, if possible, in order to increase uptime and customer satisfaction. However, if the issue is not solved, then it might be time to trade up to a newer unit with the improved switches and modules."