A hammer drill also known as an impact drill or rotary hammer is a device exactly the same as a normal cutting hand drill but has a hammering action. This action gives short rapid hammer thrusts to break down brittle material and enable the drill bit to penetrate much quicker with less effort. The smaller units are known as hammer drills but the larger high power units are known as rotary hammers, these are capable of producing huge impacts, much like a road drill. These units can be used in sometimes three different modes of operation, hammer mode, drill mode or both. Hammer drills are best suited for drilling holes in concrete, masonry and brickwork. There are two main types of hammer drill, percussion and rotary. The percussion drill has a mechanism that moves the drill chuck backwards and forwards when rotating, it can be used with or without the hammer action, but not the hammer alone as it needs to rotate. The rotary hammer is usually powered pneumatically and can only be used in hammer action only.
