Belt conveyors tension devices

Conveyors may be of parallel-chain, mat, slat, woven wire-mesh belt, or cast-alloy type. Automatic tensioning devices are used to maintain belt tension during heating and cooung. The product may rest directly on the conveyor or on special supports built into it. RoUer-conveyors are used for large pieces. Flame curtains are provided for sealing the ends and for protection of special treating atmospheres. 

Stretching of the belt can be controlled by using different types of tension devices. Two common designs are the gravity tensor and the sliding pulley illustrated in Figure 3.23. As previously mentioned, some conveyor belts incorporate an idler to snub back the belt under one pulley end to increase... 

Manually adjusted screw or ratchet take-ups that adjust the position of the tail pulley to control belt tension can be used on relatively short, light duty conveyors. Automatic take-ups are used on conveyors over about 25 to 30 m long. The most common is the weighted automatic gravity take-up (see Fig. la). Other types of automatic take-ups have hydrauHc or pneumatic powered devices to adjust a snub pulley position and maintain a constant belt tension. The requited take-up movement varies according to the characteristics of the belt constmction and the belt length. Typically, take-up movements for pHed belts are 2% to 3% of the center distance between head and tail pulley, and about 0.5% for steel cable belts. The take-up movements requited for soHd woven belts are usually shorter because of the lower elastic stretch. Take-up requirements for a particular situation should be confirmed by the belt manufacturer. 

Tail section A term used in both belt and chain conveyor work to designate that portion of the conveyor at the extrane opposite end from the delivery point. In either type of conveyor it consists of a frame and either a sprocket or a drum on which the chain or belt travels, plus such other devices as may be required for adjusting belt or chain tension. 

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