Rotary Hammer

Overview

A rotary hammer drills and breaks masonry by combining rotation with a hammering blow far heavier than an ordinary impact drill can deliver. Where a hammer drill rattles a clutch of mechanical teeth, a rotary hammer uses a sealed pneumatic mechanism: a piston driven by the motor compresses a column of air, and that air slams a free-flying ram into the bit. The result is a high-energy impact measured in joules rather than the buzz of cam teeth, which is what lets a compact 36 V tool bore 28 mm holes into reinforced concrete.

The brushless Brushless Motor feeds the Gear Train, which splits drive two ways: rotation to the hollow output spindle, and a crank input to the Pneumatic Hammer Mechanism. Bits seat in the SDS-Plus Tool Holder, an SDS-plus holder that lets the shank slide axially under each blow while still transmitting torque. The Mode Selector decides whether rotation, impact, or both reach the tool, and the Overload Safety Clutch protects the user by slipping if the bit binds. Power comes from a Battery Pack regulated through the Speed Control Board.

How it works

In the Pneumatic Hammer Mechanism, an eccentric crank bearing turns motor rotation into a reciprocating stroke of a drive piston inside a steel cylinder. The piston does not touch the ram directly. Between them sits a trapped air cushion: as the piston advances it compresses this air, the pressure accelerates the flying piston, and the ram strikes a striker bolt that passes the blow to the back of the bit. The air cushion both multiplies force and decouples the impact from the motor, so a jammed bit cannot stall the drivetrain. Seal rings keep the cushion sealed against the cylinder wall.

The Mode Selector rotates a cam that engages or disengages each path. In rotary-only mode the spindle turns but the piston is idled; in hammer-only mode the spindle is locked for chiselling; in combined rotary-hammer mode both run together for drilling. A Side Handle gives a second grip for control against reaction torque, and a Depth Gauge Rod rod sets a repeatable drilling depth.