Patent GB-652246-A (GB)
Title: Engine starter drive
IPC: F02N15/02
Filed: 1947-07-31
Abstract: 652,246. Turning-gear. BENDIX AVIATION CORPORATION. July 31, 1947, No. 20847. Convention date, Sept. 26, 1946. [Class 7(v)] In an engine starter drive including a pinion 11, Fig. 1, mounted for longitudinal movement into and out of mesh 'with an engine gear 12, there is provided means'for controlling 'the longitudinal movement of the pinion which include a. threaded connectiori, such as a screw shaft 8 and nut 13, arranged in series in the line of transmission of power and adapted to compress, after the pinion has been traversed into the operative position, a spring 24 loading a friction clutch 22 connected to one member of the threaded connection, the compression of the spring 24 being positively limited to permit the clutch to slip upon excessive 'load being applied to the pinion. The power shaft 1, has a stepped sleeve 3 attached thereto, the right-hand end of the sleeve having screwed thereon a stop nut 9. The screw shaft 8, which is journalled between the nut 9 and the sleeve step 7, is in threaded connection with the nut 13 that is fixed to one end of a barrel 14, whilst the other barrel extremity is joined to the pinion 11, which latter is slidable upon the shaft 1. To the left-hand end of the screw shaft 8 is attached another barrel 17 to which are splined the driven discs 21 of the clutch, the driving discs being splined to the sleeve 3. A thrust washer 10 on the step 7 limits the compression of the clutch loading springs 24 and hence the torque transmitted by the clutch; the springs 24 being maintained under an initial light compression by another thrust washer 27 interposed between the screw shaft and stop nut 9. Rotation of the power shaft 1 is transmitted through sleeve 3, clutch barrel 17 and screw shaft 8 and causes the nut 13 and hence the pinion to move into engagement with the engine gear 12, after which, or in the event of tooth abutment, the screw shaft moves leftwardly and further compresses the springs 24 until sufficient torque is transmitted through the clutch to crank the engine or partially rotate the pinion to effect indexing, whereupon axial movement of the pinion into mesh with engine gear 12 is effected by the expansion of springs 24. In a modification, the power shaft 31, Fig. 4, has a solid screw shaft 32 rigidly coupled to it, the latter having a reduced-smooth portion 33 surrounded by a sleeve 34 whilst the pinion 35 is slidably journalled on the sleeve. A nut 38 which is threaded on the screw shaft 32 has splined thereto a driving clutch-member 41, whilst the driven clutch member comprises a barrel 42 attached to the pinion, the clutch discs being located between member 41 and 42. The member 41 is loaded by springs 48 which are adjusted for compression by a backing nut 51 on the nut 38. The nut 38 and member 41 are provided with lugs and held as an essembly by a lock ring 55 located between the two sets of lugs, which ring also maintains initial compression of the springs 48 whilst a thrust washer 56 abutting the sleeve 34 limits the compression of these springs. In a further modification, the power shaft 61, Fig. 5, has a solid-stepped extension-shaft 62 fixed thereto upon which is slidably journalled a screw shaft 65, a pinion 66 being threaded upon the latter. A barrel 69 is fixed to the screw shaft and clutch discs are splined to the shaft 62 and barrel 69. A ring 74 of rubber or similar material is mounted in the barrel to form an elastic abutment for the clutch discs. The. initial pressure on the discs is adjusted by a backing nut 77 threaded on the end of the extension shaft 62 and the limitation on the maximum-transmitted torque is effected as in Fig. 1. The loading of the clutch to effect cranking of the engine or indexing of the pinion is brought about by the joint action of the rubber ring 74 and the clutch springs 76. Upon the return of the parts to the idle position the kinetic energy of the parts is, as in all the embodiments, dissipated by slipping of the clutch.