In industrial control applications the conveyor may be used as a variable rate feeder to deliver a measured rate or quantity of material into a process.
Screw conveyors can have a greater pitch spacing, resulting in a higher capacity without an increase in rotation speed. They usually consist of a trough or tube containing either a spiral coiled around a shaft, driven at one end and held at the other, or a Shaftless Spiral, driven at one end and free at the other.
Screw conveyors can be operated with the flow of material inclined upward. When space allows, this is a very economical method of elevating and conveying. It is important to understand, however, that as the angle of inclination increases, the allowable capacity of a given unit rapidly decreases.