Full definition
A pulley mounted on a movable carriage or frame that maintains proper belt tension by compensating for belt elongation (stretch) due to elastic extension under load, thermal expansion, and permanent set over time. Two main systems: (1) Screw take-up — drum positioned by threaded rods on sliding rails; manually adjusted; travel: 1-3% of belt center distance; for conveyors up to ~100 m. (2) Gravity take-up — drum on a guided carriage with counterweights providing constant tension force; self-adjusting; travel: 1.5-3% of belt length for textile belts, 0.5-1% for steel cord; for long conveyors. Location: typically near the tail (low-tension end) for gravity take-ups, or at any convenient low-tension point. Counterweight mass: W = 2 × T₂ (twice the required slack-side tension). The take-up must accommodate both initial belt stretch during run-in (1-2% for EP belts) and ongoing creep over belt life. Per CEMA 7th Edition and DIN 22101. Inadequate take-up travel causes belt slip on the drive drum and potential belt damage.