| 摘要 |
1,197,393. Friction clutches. INGERSOLL-RAND CO. 8 July, 1968 [31 Aug., 1967], No. 32507/68 Heading F2C. [Also in Division B3] A pneumatically operated nut-runner, Fig. 1, has a friction clutch which automatically disengages when the torque transmitted reaches an adjustable pre-set amount. The clutch comprises two members with mating tapers 22, 23, Fig. 3, the member 22 being driven by a member 13 through balls 25 which seat in recesses 26, 27. The members 13, 22, 20 are urged into driving relationship by a spring 35, Fig. 2, which is adjusted by a nut and a " Jacobs " type chuck key 40, to pre-set the torque at which the clutch disengages. When the limiting torque is reached the balls 25 ride up the sides of the recesses 26, 27 and force the members 22, 20 away from the member 13 by an amount which is limited by a circlip 31. This movement depresses a valve 45, Fig. 2, which is attached to the member 20 by a bearing 33. When the valve 45 meets a shoulder 52 the air exhaust 44 is closed. This causes the driving motor 7 to stop and pressure to rapidly build up across the valve 45. The pressure developed pushes the valve down on to a shoulder 53 and as it descends the valve pulls the member 20 out of engagement with the driven member 22 thereby disengaging the clutch. When the air supply is cut off by the lever 5 the clutch re-engages. In a second embodiment, Fig. 6, the valve 45 is mounted on the bearing 33 with lost motion and restrained by a light spring 58. This allows the pressure across the valve to close the air exhaust before the pressure is great,enough to disengage the clutch thereby providing quicker operation. In a third embodiment, Fig. 7, cam notches 62, 63 up which the coupling balls ride are shaped as shown. This ensures that once the balls are over knees 66 they can roll up the slope 65 under a torque which is smaller than that originally required to initiate the movement. |
