Machine Design

Berke on Safety: Simple Design High on the Safety Ladder

I’m devoting today’s column to a case where thoughtful engineering led to an elegant design that improved worker safety. The following is from Scott Clay, a technical service engineer and eTool development supervisor with the 3M Communication Markets Div., Austin, Tex., who was instrumental in developing the kit he describes. — Lanny Berke

Field technicians in the communications industry need to securely mount tools and keep them within arm’s reach. Whether climbing an extension ladder to work on an aerial line, splicing cable, or performing repairs, the technician wants to be confident their splicing rig or fiber workstation will remain firmly in place through whatever extremes they face in their workday.

Historically, workers screwed a mounting plate directly into the side rails of wooden ladders to attach rig-mounting equipment. But because wood ladders are heavy and require maintenance to prevent rotting, many companies switched to lighter, more-durable fiberglass ladders. Unfortunately, the traditional mounting plate didn’t attach well to the fiberglass ladders’ U-shaped rail. Moreover, screws inserted into the fiberglass damage the rail.

Technicians’ workaround was to place a two-by-four wooden block into the U-shaped channel. The resulting flat surface let them clamp a vise on the ladder rail to which the rig-mounting equipment could attach. This “MacGyver” approach solved the problem, but it weakened and sometimes cracked the ladder rail.

A committee member for a large telephone-operating company was assigned to find a better way. His call to 3M led 3M engineers to work closely with phone company technicians to design the 3M Ladder Kit 710/MS2-TMK-LK. The portable, lightweight kit consists of two clamp assemblies and a flat-sided, 4-ftlong aluminum bar. The clamp assemblies attach the bar to the ladder rungs and other surfaces that would otherwise be unstable tool-mounting locations. The bar provides a stable surface where tool-mounting components can attach. An optional extended bar expands mounting options.

Technicians perform initial setup of the bar-and-clamp assembly on the ground and then secure it on a ladder rung at ground level. The flat side of the bar rests evenly on the ladder rail to minimize wear. Once positioned, the assembly can be transported as a single unit in its carrying case which is about the size of a golf bag.

The telephone-operating company field tested the ladder kits, and feedback from technicians was overwhelmingly positive. The company has since approved the kits for use across the U.S. — proving that simple ideas are sometimes the best.

Lanny Berke is a registered professional engineer and Certified Safety Professional involved in forensic engineering since 1972. Got a question about safety? You can reach Lanny at [email protected].

Edited by Jessica Shapiro

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