Rotor 1 rotates about fixed axis A and has four vanes b which slide in slots of rotor 1 and are held by centrifugal force against the wall of cylindrical chamber d whose axis is located eccentrically with respect to axis A. Sun gear 6, rigidly mounted on the shaft of rotor 1, meshes with three planet gears 2 which, in turn, mesh with internal gear 3, rigidly secured to the body of the drill. Planet gears 2 rotate about axes B of carrier 4 which is rigidly mounted on drill spindle 5. Air admitted through hose a rotates four-vane rotor 1 whose rotation is transmitted through planetary gearing to spindle 5.
$4039$THP,FD$