Abstract: A power tool combination including a hammer drill, an adapter secured to the drill for attaching it to an elongated rod which bears on the floor, a pneumatic cylinder and piston unit mounted between the elongated rod and the drill for applying an uniform external force for moving the power drill into the ceiling, and a coupling member between the pneumatic piston and cylinder unit. The coupling member is rigid for transmitting axial forces therethrough under normal operating conditions but is capable of yielding to absorb abrupt shock forces in the event that the drill encounters an undesirable obstruction in the ceiling, the coupling member including structure for causing it to return to a normal rigid condition after the shock forces have been absorbed.