TAKE-UP PULLEY

The take-up pulley is the active tensioning element of a conveyor. It is a bend-type drum mounted in a sliding carriage on the return strand of the belt; the carriage is then pulled in the direction that pays belt into the loop by either a hanging gravity weight (gravity take-up) or a manual or motorized screw (screw take-up). The take-up force is what establishes the slack-side tension T2 at the drive pulley — and through T2 the tight-side T1, the carry-side [belt sag](/glossary/belt-sag), and the margin against drive slip per the Eytelwein equation.

Gravity take-ups are the standard choice for any conveyor longer than about 60 m, because they automatically maintain constant T2 as the belt stretches, ages, and varies with temperature. The carriage travel must accommodate the total expected belt elongation: roughly 1.5–3 % of conveyor length for fabric belts (more travel) and 0.5–1 % for steel cord (less travel). Screw take-ups are simpler and cheaper but require manual periodic re-tensioning; they are restricted to short conveyors (typically <60 m) where elongation is small enough to absorb between maintenance intervals.

Sizing the take-up weight or screw load is derived from the maximum required T2 in any operating case — usually full-load startup or emergency stop, when transient tensions exceed steady-state Te. The take-up must also be located where T2 occurs in the belt circuit (immediately downstream of the drive on a single-drive head-drive layout), not at an arbitrary point.