Since one piece of equipment will not perform every conveying function equally well, three very definite types of concrete conveyors have been developed. The first is the portable conveyer- for short lift-reach applications; the second is the feeder conveyor- for the carrying applications; and the last is the side discharge or spreader conveyor for the spreading applications. The relatively short lift-reach application is covered by the portable conveyor. This conveyor is just what its name implies- a completely self-contained unit usually with a gasoline power source, mounted on rubber tires and able to be towed by a pickup truck or car from job to job. Because these conveyors must be road portable and light enough to be moved around a job, they have definite practical limitations as to length. Very few portable conveyors will have booms shorter than 40 feet and longer than 56 feet. A 40 foot conveyor at a 30 degree angle of elevation provides a discharge height of 28 feet. These conveyors are almost always equipped with a ribbed or corrugated belt so they can handle concrete at an angle in excess of 30 degrees at a reduced capacity. Feeder conveyors are just what the name implies. They feed concrete from one conveyor to another and ultimately to the forms or to a spreading conveyor. The feeder conveyor is really a type of conveyor rather than a specific machine. The length can vary from 24 feet to 85 feet. Obviously the problems of handling 85 foot long conveyors are different from the problems involved in handling, 30 foot conveyors and job conditions will dictate the best length conveyer for a given application. The side-discharge conveyor, developed specifically to place concrete in front of mechanical finishers, can be charged either by a ready mix truck, a portable conveyor, a train of feeder conveyors, or by a crane and bucket. The side-discharge conveyor operates with a belt speed of about 400 feet per minute and since it is operated normally in a horizontal position it too has a very high theorticaly capacity. Since the conveyor spreads concrete along its full length and is self-propelled almost no limitation is imposed on capacity as long the finishing machine can keep up the pace.