GB817276A - Pneumatic gear-shift device for change-speed gears - Google Patents

Abstract

817,276. Gearing for stopping and starting machinery; clutches; change-speed gear. MOOSMANN, A. Sept. 12, 1955 [Sept. 13, 1954], No. 26090/55. Class 80 (2). In a pneumatic gearshift for a change-speed gear, a diaphragm or equivalent is interposed between the air supplies for a pneumatic friction clutch and a pneumatic friction brake to prevent engagement of one before disengagement of the other. A gear 1 transmits the drive through a friction clutch 2, engaged against pressure of a spring 21 by a pneumatic cylinder and piston 3, to a gear 4 on a shaft 6. The shaft 6 carries a second gear 7 and a pneumatically engaged friction brake 16. The gears 4, 7 engage gears 5, 8 clutchable by sliding dog sleeve 10 to an output shaft 9. The sleeve 10 is moved axially by a shift rod 11 and pneumatic piston 12 to selectively engage either gear. Air for the operation of the clutch 2, brake 16 and piston 12 is admitted through connections 23, 18, and 14, 15, respectively. The change-speed gear is controlled from a programme controller of the type described in Specification 813,381, [Group XXII]. For engagement of clutch 2 air from the controller passes to connection 24 in the shift device, Fig. 2, through a change-over device 25 and bore 26 to a diaphragm chamber 28, thence to a restrictor nozzle 30 and non-return valve 31, closed for the passage of air in that direction, to a bore 35 connected with connection 23. The bore 35 is also in communication with the diaphragm chamber of an impulse-valve 39 which provides a completion of engagement signal to the controller. Engagement of the brake is provided. by air pressure to bore 41 and venting of connection 24. Pressure frombore 41 passes to a restrictor nozzle 43 and non- return valve 44 and thence to bore 45 which is closed by the diaphragm 27 until the pressure in the clutch system has bled away to release pressure in chamber 26. When the bore 45 is opened pressure flows through diaphragm chamber 46 to bore 47 and thence to brake connection 18. An impulse valve 53 signals completion of the brake engagement, and the driven machine can either remain braked or a change of speed be initiated by the programme controller. Combination of the strength of the clutch and brake disengaging spring with the strength of the springs in the non-return valves provides a rapid drop in pressure for the first phase and a slow drop, with continued holding by the diaphragm 27, for the fmal phase of clutch and brake release, and prevents engagement of clutch and brake simultaneously. To prevent the transmission of high torques at low speeds the controller may direct air pressure for clutch engagement to connection 54 under such conditions, from this connection the air passes through a reducing valve 55 to passage 62 and the change-over device 25 then closes bore 24 and passes air to bore 26 for the clutch engagement to function normally at reduced pressure, and thus limit the torque transmitted by the clutch 2.