Full definition
A pulley mounted on a movable carriage or frame that uses gravity (dead weights) to apply constant tension to a belt or cable system, automatically compensating for elongation, thermal expansion, and load variations. The counterweight force is set to maintain the required minimum belt tension under all operating conditions. Travel distance sized for expected belt stretch over service life. Common in: conveyor gravity take-up systems (travel = 1.5-3% of belt length), elevator compensating sheaves, vertical reciprocating conveyors, and variable-stroke machines. The counterweight mass is calculated from required tension: W = 2 × T_slack (for a gravity take-up bend pulley). Advantages over screw take-ups: automatic, constant tension, no manual adjustment. Disadvantages: requires vertical space, higher initial cost. Per CEMA 7th Edition for conveyor take-ups. Guide rails or tracks ensure linear carriage travel without binding.