Two general types of conveyor units exist: powered units with motors, and unpowered units that are gravity-fed. Motorized units can run off of electricity or gasoline, while unpowered units are usually placed on an incline to allow materials or objects to move freely over rollers down a slope. The variation in design of conveyor units, whether powered or unpowered, can be quite extensive: belt conveyors feature a rubber belt on which objects can be placed, while auger conveyors feature a large screw known as an auger concealed within a frame or body.
Wire mesh conveyor units replace the standard rubber belt with a wire mesh belt. This is often used in applications in which heat or sanitation is a factor. In food processing, for example, a wire mesh belt is more appropriate for several reasons: first, it can be washed very easily; second, it is less likely to contaminate food; third, if the food must be exposed to a heat source such as an oven used for cooking, a rubber belt would melt or otherwise become damaged, while a wire mesh belt will not succumb to heat damage.
Cleated belt conveyor units are often used in industrial settings such as quarries, mines, construction sites, and even in factories. These units are generally oriented on an incline, which means the materials transported on the conveyor system will start at the bottom of the belt and move diagonally upward. The belt will feature cleats, which are essentially teeth that will allow materials to be transported upward without falling back down the belt. The cleats may be made of rubber or metal, depending on the intended application.
If exceptionally fine materials such as sand will be transported, auger conveyor units are the most appropriate choices. These units feature a large screw contained within a frame, and when the screw is rotated, the materials will be transported directionally according to the orientation of the screw. This system works well because the fine materials are less likely to get caught in various moving parts, or to fall through the machine or off the sides of a belt.
A gravity roller conveyor is a system that does not use motorized power. A metal frame will contain a series of metal rollers or cylinders that rotate as objects are pushed over them. The conveyor may be oriented on a downhill slope, allowing gravity to pull objects along with little or no human assistance.