Apparatus for reflex-percussive cutting of concrete etc.

Apparatus for cutting a groove in the surface of a hard material by reflex percussion, characterised in that the apparatus includes:

• a pneumatically operated piston;
• a cutting bar, which is arranged for direct cutting contact with the surface to be cut;
• a frame, which includes a cylinder in which the piston is mounted for reciprocating movement along an axis of reciprocation;
• a means for fixing the cutting bar to the piston to form a hammer assembly, the said means being such that the piston and cutting bar are, at all times during operation, constrained against all movements relative to each other in the direction of reciprocation;
• a double acting pneumatic circuit, which is effective to force the hammer assembly under pressure hard onto the surface to be cut, and is effective then to drive the assembly, under pressure, away from the surface, before the hammer assembly naturally bounces clear of the surface;
• a drive means for moving the cutting bar over the surface, and along the line of the groove to be cut;
• and an anti-rotation means, which is effective to constrain the cutting bar against rotation relative to the frame, about the axis of reciprocation.