Patent GB-993381-A (GB)
Title: Improvements in reversible pressure fluid driven portable tools
IPC: F01D1/30
Filed: 1963-10-15
Abstract: 993,381. Dental engines. ATLAS COPCO A.B. Oct. 15, 1963 [Oct. 22, 1962], No. 40631/63. Heading A5R. [Also in Divisions F1 and F2] A reversible pressure fluid driven motor for self-contained dental engines comprises a housing, a rotor mounted for rotation in the housing, fluid admission passages in the housing for forward rotation of the rotor, fluid admission passages in the housing for reverse rotation of the rotor, fluid outlet passages in the housing distinct from the admission passages for conducting fluid from the rotor and means in the admission passages for selectively admitting fluid through one or the other of the admission passages to the rotor for forward or reverse rotation thereof, respectively. In the dental machine shown the motor is a turbine although it is stated that the invention is also applicable in the case of a sliding vane motor. The assembly comprises a housing formed of a forward portion 1 and a rearward portion 2 which are in screwed connection at 3, the portion 1 comprising an air inlet portion 4 to which is connected a hose 5. A spring- loaded ball valve 10 is disposed in the inlet 4, the ball being opened against the force of the spring by means of a rod 26. The rod 26 is engaged against a recess 27 in a sleeve 23 which is axially movable within the casing 1. Air from the inlet 4 may pass through a passage 11  to a chamber 7, thence through either nozzles 8a or 8b formed in the nozzle plate 9, depending on the desired direction of rotation, and on to the blades of the turbine rotor 6. The fluid discharges from the rotor into the annular chamber 12 and thence through outlets 13 to atmosphere. The rotor 6 is supported within the housing 1, 2 by means of bearings 17, the outer race 16 of the downstream bearing being a press fit within the housing portion 2, and the outer race 16 of the upstream bearing being supported within the housing portion 1 by means of an annular disc 19 of rubber or like material, this arrangement allowing axial movement of the race 16. A spring 25 is disposed between the axially-movable race 16 and the axially-movable sleeve 23. The inner races 15 of the two bearings are mounted on a cylindrical sleeve 14 to which is secured the rotor disc 6. The drive shaft 20 is secured by means of pins 24 to the ball carriers 18, the arrangement being such that power is transmitted from the rotor 6 to the shaft 20 by means of the balls 17 and the ball carriers 18 operating as a friction type of planetary gear. Mounted for rotational movement between the nozzle plate 9 and the turbine rotor 6 is a control member 30 which has openings 31 at its periphery, the member being movable so that the openings co-operate with either the nozzles 8a to produce forward rotation of the rotor or the nozzles 8b to produce reverse rotation of the rotor. The control member 30 is movable by means of an operating ring 39 disposed externally of the housing portion 2, the ring being connected to the control member 30 by means of a spring 42 and a tubular sleeve 32. Specification 785,109 is referred to.