Tension Capacities of Running Skyline Yarders
ABSTRACT LOGGING planners have used 'safe' working tensions, usually one-third of breaking strength, when estimating payloads. Yarders have not always been able to handle the loads predicted on this basis. This study examined, via theoretical modeling of the drive trains, the capabilities of fifteen yarders which could be rigged as running skylines. We found that, in many cases, lines could not be tensioned to one-third of breaking strength due to clutch, brake or interlock limitations. For some interlocked yarders, payloads in downhill yarding at low speeds may be considerably less than those predicted with *safe' tensions because these yarders rely on engine braking to dissipate energy..