GB1315903A - Percussive drills - Google Patents

Abstract

1315903 Rotary-percussion drills METABOWERKE CLOSS KG RAUCH & SCHNIZLER 1 June 1971 [16 June 1970] 18262/71 Heading B3C [Also in Division B4] A percussive drill comprises a tool holder 2 mounted in casing 1 for rotation and axial movement, a non-rotatable reciprocable hammer piston 16 for applying blows to the rear end 11<SP>1</SP> of the tool holder, and means for enabling the drill to operate with percussion alone, or with percussion and rotation of the tool holder at either of two speeds. A motor (not shown) has an output shaft 4 which drives a shaft 28 via gear 34 and slipclutch 46. Gears 32, 33 secured to the shaft 28 mesh respectively with gears 29, 31 freely mounted on shaft 27. A key 35 is axially movable along shaft 27 by a manually operable rack and pinion mechanism 40-42 to lock gear 29 or gear 31 to gear 30. In an intermediate position of the key neither gear 29, 31 is locked to gear 30. A gear 13 freely mounted on the shank 11 of the tool holder is continuously rotated via gears 33, 31, and a gear 12 secured to the shank 11 is in continuous engagement with gear 30. In operation when the drill is applied to a workpiece the tool holder will be moved axially against bias of spring 26 to bring dogs 25, 14 into engagement. The part 5 will be rotated and will, through interengaging cam teeth 15, 17 and spring 21, cause axial reciprocation of the piston 16 and application of blows to the tool holder. With the key 35 in the illustrated position rotary drive will be imparted to the tool holder via gears 32, 29, 30 and 12. When the key is moved to the intermediate position rotary drive is disconnected; and when the key locks the gears 30, 31 the holder will be rotated at a different, slower speed.