Pneumatic engraving tool

Claim 1

A fluid actuated, portable engraving tool, comprising, in combination: a. a body provided with an opening; b. a tracing assembly mounted on the body and arranged for engaging in a suitable template; and c. a unitized fluid motor assembly arrangeable in the opening of the body, said motor assembly including, a spindle, an engraving means attached to said spindle, a motor cap, a bearing affixed onto the spindle for rotation therewith and received in a recess provided in the motor cap, a fluted rotor affixed to the spindle, and a further bearing affixed to the spindle and arranged bracketing the rotor in cooperation with the bearing, a cavity provided in the body and arranged in communication with the opening of the body for forming a chamber receiving the rotor, a tube entering the body and terminating at an interface between the rotor and the chamber receiving the rotor, the tube providing a passage for injecting a fluid under pressure and impinging same on a fluted circumference of the rotor, and the body member is further provided with a labyrinth, a short partition dividing the labyrinth so as to cause a reversebend of the exhaust fluid flow, and a foamed material arranged in the labyrinth for exerting a back pressure on the fluid under pressure and forcing a lubricant carried in the fluid under pressure to be forced into the bearing and further bearing.