Portec Positive Drive/Loose Belt Technology

Sigma Belt

Proven Design

Unlike friction drive straight conveyors, the Portec Belt Power Curve conveyor does not use the end roll to drive its conveyor belt. The belt is driven by its outside edge by the belt drive chain.

Special attachment links connect the belt drive chain to a series of grommetted holes along the outside edge of the belt. The drive chain is positively driven by a shaft-mounted sprocket. The positive drive arrangement is unaffected by changes in loading, tension, temperature, humidity and foreign material getting between the bottom of the belt and the end rolls. When conditions change, there is no requirement for immediate attention to maintain the functional operation of the conveyor. Because the belt is merely a carrying surface and high tension is not required for operation of a chain driven conveyor, belt life, as well as integrity of belt joints, is greatly enhanced. The positive drive design is also very conducive to using mechanical lacing because concerns of damage to the end roll lagging (no lagging is required) are non-existent. Even in difficult access areas of a conveyor system, mechanical lacing allows for fast and efficient belt changes because, unlike conveyors with vulcanized endless splice belts, extensive disassembly of the conveyor is not required.

In contrast, friction driven belt conveyors require exact tension control and adjustment to continue operation, and small changes in conditions can immediately affect funtionality. On friction drive units, high belt tension to maintain drivability transmits high stress levels to the belt joints; decreasing belt life and increasing maintenance demands. Also on friction driven units, end roll components (shafts, bearings, pulleys) are subjected to much higher stress levels due to the required belt tension. Life expectancy of these components is necessarily shorter.

Contact: sales@portec.com
Phone: (719) 275-7471
Fax: (719) 269-3750

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