Drilling bucket

The bucket rig is a form of the rotary drill rig. It uses mechanical or hydraulic drive to rotate a kelly, which is attached to the bucket. This type of rig normally will utilize a square friction-type or round locking-type kelly, with three or four telescoping sections that can extend to 100 feet or more. Bucket rigs may be equipped to drill holes from 10 inches to 60 inches in diameter. Bucket drilling uses a cylindrical bucket with cutting blades or teeth mounted on a hinged bottom to repeatedly cut and lift sediments from the borehole. 

To drill, the bucket is rotated to allow the bottom of the cutting teeth to fill the bucket. When the bucket is full, it is raised by cable. Flaps at the bottom of the bucket will close to keep the soils (spoils) inside the bucket. The bottom of the bucket, which is hinged, is opened to allow the soils to dump into the spoil pile. The bottom of the bucket is closed, the bucket is reinserted into the hole, and the process is repeated as necessary to achieve the proper borehole depth.