Abstract: A clamp arm for attachment to the plunger of a clamping cylinder has a body with a central opening for receiving the plunger and a working arm portion extending outwardly from the opening. The body has a radial slot extending from the central opening and a bore in the body that extends transversely through the slot. One portion of the bore is threaded to receive a headed bolt to draw the sides of the slot together to lock the body on the plunger. The body is axially restrained on the plunger by means of a ring received in a counter bore above the transverse bore for the headed bolt. The ring is received in a circumferential groove in the plunger. Alternatively, the headed bolt that is used to draw the sides of the slot together engages a circumferential groove in the plunger.

Abstract: When the hammer drill spindle and chuck are driven forward with the mode selection collar positioned to allow axial movement of the chuck and spindle, the annular ratchet is driven by the spindle through a one way roller clutch so it rides up the sloping surfaces of the fixed annular ratchet and then drops off the tooth corners to deliver a hammer blow of a magnitude determined by the operator pushing on the tool. If the rotation is reversed the clutch prevents rotation of the clutch input and prevents injury to the operator. If the selection collar is moved to lock the lugs in the detent notch of the cam surface the drill can be rotated either direction with the hammer action always locked out.