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A bucket elevator is a simple machine used to transport bulk materials or powders vertically. The most common use for this technology is for moving grain into a silo from the ground. These devices have been around for over a century and are still one of the most reliable ways to lift a variety of materials safely and efficiently. They use gravity and other physical forces to feed, lift and empty a product stream into the desired location. Some models can be used to handle liquids or fragile objects, though these are designed a little differently.
There are four versions of the bucket elevator, including centrifugal, continuous, positive discharge and internal discharge. The common models are the centrifugal and continuous versions. Centrifugal lifts are typically installed in areas where bulk grains and other agricultural products need to be moved. They are also installed around grain silos to transport material into huge containers.
These machines consist of a few simple processes to lift material. An inlet chute at the bottom of the machine is first fed a constant stream of product. Buckets attached to a belt descend and scoop up the product as they pass through the bottom of the shaft. This shaft may ascend hundreds of feet high and is filled with scoopers that move up and down with the belt. When they reach the top of the shaft, they in turn empty their material into discharge throats that channel the stream into a container. As each scooper empties its load, it is returned to a sprocket or pulley near the bottom of the shaft where the process repeats itself. Though the process may look like haphazard, a bucket elevator is actually calibrated to feed at a continuous rate and dispenses a constant level of volume. These machines come in a variety of designs, each created to handle a certain amount of volume and material weight.
A centrifugal bucket elevator discharges material differently than a continuous model. Centrifugal devices have higher speed motors that move the belt faster. As scoopers near the top of the shaft, the sudden switch from upward to downward movement creates enough centrifugal force to throw the product into discharge throats. These models are typically reserved for agricultural products that can withstand impact against the side of the shaft, like grains or nuts. Centrifugal models are often designed with anti-abrasive materials to prevent metal erosion.
Continuous lifts operate at slower speeds and are better for fragile material or liquid. They are also used when transporting powders or other light product that can’t be aerated. A continuous bucket elevator doesn’t use centrifugal force to fling material into discharge throats. Instead, as each scooper reaches the top of the shaft, it turns over and empties its load into a discharge shaft under the top of the belt. Each scooper is shaped to direct falling materials into this chute, so the only force needed is gravity.
These lifts are generally safe and are effective at keeping dust from spreading. The internal shaft contains dust and powder, both of which are common hazards in the agricultural industry. This safeguards worker health and lowers the chances of a fire.
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