Cable Yarding in Southern Africa: An Analysis of its Productivity and Possible Procedure for its Improvement

Abstract

ABSTRACT The demand for timber in southern Africa is increasing and this is resulting in the afforestation of areas which require cable yarding when harvested. The demand for cable yarders, essentially fixed skylines, is therefore increasing rapidly. Stress is being placed on the productivity of skylines since about half the timber has a piece size of under 0,2 m3. Work study analyses showed that much productivity was lost from slow carriage turn-about times caused mainly by inefficient choking techniques, slow carriage speeds, small load masses caused again by inefficient choking and by unwarranted delays. The productivity of the skyline was nearly tripled by fitting an automatic transmission gearbox to the drive to increase carriage speed, by using a single locking carriage that could also accommodate tag lines, and by the development and use of suitable tag lines. Timber piece size had little effect on timber productivity.