Patent GB-665602-A (GB)
Title: Clutch device for transmitting rotary movement
IPC: F16D67/06
Filed: 1947-06-23
Abstract: 665,602. Friction clutches. BENDIX AVIATION CORPORATION. June 23, 1947 [July 1, 1946; July 1, 1946], Nos. 16580/47 and 16581/47. Class 80 (ii). A screw-jack actuator, for aircraft, has a friction clutch and brake, in which the clutch is engaged by or through a first spring when actuating means, such as an electromagnet, is operated to disengage the brake against a second spring which normally maintains the clutch disengaged and the brake engaged. In all except Fig. 9 of the many forms described, the first spring normally supplies the engaging load for the clutch, and the second spring is stronger than the first so as to disengage the clutch and engage the brake when the magnet is de-energised, whilst in Fig. 9 only, the first spring 360 acts only as a resilient strut transmitting the engaging thrust of the magnet to the clutch. In Fig. 1, a first spring 86 moves a clutch-disc 84, splined on the driven shaft 74, axially into frictional engagement with an axially-immovable clutch-disc 92, fast on the motor - armature - shaft 94, when an electromagnet 108 is energised, simultaneously with the motor, to attract an armature 112, connected by pins 116 to a brakedisc 118, which, in the de - energised condition shown, is pressed by second springs 122, stronger than the clutch-spring 86, into engagement with the driven disc 84, to lift it off the driving disc 92 and simultaneously brake it. The brake-disc 118 is prevented from rotation by the pins 116 which slide in a fixed casing-member 102. In the clutch-engaged position, abutment of the brakedisc 118 on the fixed part 102 limits rightward movement of the magnet-armature 112, leaving an air-gap, which, together with the use of a laminated magnet core 108 and armature 112, see Fig. 5, avoids sticking when the magnetwinding 110 is de-energised. Limit switches are operated by cams on a transverse shaft 60, and Belleville washers 46, cushion the arrest of the ball-threaded nut 24 at the limits of its travel, preventing jamming. In the clutch-disengaged position shown, leftward movement of the brakedisc 118 is limited by abutment of the magnet armature 112 on the fixed member 102, thus limiting brake-pressure so that, in the event of failure of one of a pair of coupled actuators, the other would be able to overcome the brake and complete the movement. In Fig. 6 (not shown), the additional bearing 96 for the shaft 94, and also the pins 116 are dispensed with, and the brake-disc, which is mounted directly on the armature 112 slides on shouldered fixed pins formed by elongating the pins 120 inside the brake-springs 122, leftward movement of the driven clutch-disc being limited by a cup surrounding its spring 86. Fig. 7, not shown, uses a non-laminated magnet-core of annular pot-form acting directly on a non-laminated brake-disc. In Fig. 9, the driven clutch-disc 330 is fast on the driven shaft 346, both being moved axially together to engage the driven disc 330 with either the brake-disc 320 on one side or the driving clutch-disc 326 on the other. An annular pot-magnet core 334 attracts an armature-disc 342 at its end remote from that of the clutchdisc, first compressing the second springs 358 and later, through a ball-bearing 356, compressing the stronger central first spring 360 through which pressure is applied to urge the driven clutch disc 330 into engagement with the driven 326. A non-magnetic peripheral ring 374 preserves an air-gap. De-energising the magnet first permits the central spring 360 to expand, whereafter the lighter springs 358 act on the shaft 346 through the armature-disc 342, bearing 356 and shaft-collar 370, to move the driven clutch-disc 330 axially into engagement with the brake-disc 320.