Hammer drills have a cam-action or percussion hammering mechanism, in which two sets of toothed gears mechanically interact with each other to hammer while rotating . the drill bit.They are also used to drill holes in concrete footings to pin concrete wall forms and to drill holes in concrete floors to pin wall framing. Ultimamac has wide variety of Hammer Drill Spare parts. You can get Original Hammer Drill Spares under one roof from Authorized and genuine dealer at the lowest price.