Cablecraft Solves Tough Engineering Problem

Cablecraft Motion Controls was contacted in late 2017, by a large Lawn & Garden OEM, in search of pricing for a special mower deck-height lifting linkage. A cross functional Cablecraft team met with their counterparts, from the OEM, to review the application. Samples and drawings were released as well as application specifications.

One specification indicated that the rod-end pull-out (breaking point) force requirement was approximately 16,000 pounds. Cablecraft Engineering found that the linkage had ½”-20 threaded rod ends, or an industry-standard equivalent to an SPF8 rod end. Engineering concluded that the supplied rod end would not meet the specification referenced in the supplied drawings. Cablecraft could provide a rod-end that could easily handle the load; however, it must be heat treated and could not be assembled per the OEM’s requirements. The specification stated the rod ends must be staked, to the rod, at a certain distance (staking is a process where the rod ends are crimped in a press, effectively smashing the rod end onto the rod for a more-secure connection). These heat-treated components would crack under the load of the press and fail the pull-out test. This, along with the extra cost of the heat-treated components, made this idea impractical.

Cablecraft advised the OEM that if their force test specifications were correct, a much larger rod end would be required. The equivalent of a 1” rod-end, which Cablecraft did not manufacture, more expensive and much larger.

The OEM informed that the larger rod end would not fit into their tight space constraints.

Under the OEM’s guidance, Cablecraft decided to perform its own pull-out test on the provided linkage. This testing showed that the actual pull-out force, of the supplied samples, was approximately 6200 pounds; less than half that originally specified. The test results confirmed our hypothesis that there was an error in the OEM’s original pull-out force calculations. Cablecraft re-engineered the rod-end and linkage under the new pull-out force which was determined to be 7000 pounds. This finding enabled Cablecraft to provide a cost-effective solution using a standard, non-heat-treated rod-end (EF8). This new linkage was well within the capabilities needed to meet the application.

Cablecraft provided samples to the OEM for testing, the results of which concluded that the redesign met all requirements and at a much-reduced cost. The project was awarded to Cablecraft and the Cablecraft rod end (EF8) was specified, as sole source, on the OEM drawings. This project was a great collaboration with the OEM and Cablecraft. The company’s extensive engineering expertise and highly flexible lean manufacturing environment have historically produced a wide range of cost effective motion control solutions for OEM industrial, commercial, and high-performance applications.

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