Rotary hammer driving mechanism

摘要

A rotary hammer has a reciprocating piston of a pneumatic impact mechanism driven from a rotatable drive shaft. A coupling element is fixed on, and a drive element slidably mounted on, the drive shaft. These elements have interengageble tapered coupling surfaces and are biased apart by a spring therebetween. The drive element is disposed forwardly of the coupling element and is slidable rearwardly to drivingly engage the coupling surfaces for transmitting drive to the piston. The relative disposition of the drive and coupling elements causes reaction force on the piston, consequential in use upon generation of percussive blows, to urge the drive element into intensified engagement with the coupling element.