More Details: A rotary hammer is a power tool that can perform heavy-duty tasks such as drilling and chiselling hard materials. It is similar to a hammer drill in that it also pounds the drill bit in and out while it is spinning. However, rotary hammers use a piston mechanism instead of a special clutch. This causes them to deliver a much more powerful hammer blow, making it possible to drill bigger holes much faster. Compared to less advanced power units known as hammer drills, rotary hammers tend to be larger and provide a bigger impact force by utilizing a technology called the “electro-pneumatic” (EP) hammering mechanism, because it is powered directly by electricity instead of a separate air compressor. Rotary hammers have two pistons – a drive piston, and a flying piston. An electric motor turns a crank, which moves the drive piston back and forth in a cylinder.