Patent GB-650627-A (GB)
Title: Improvements in or relating to engine-starter drives
IPC: F02N15/06
Filed: 1948-05-05
Abstract: 650,627. Turning-gear. BENDIX AVIATION CORPORATION. May 5, 1948, No. 12391. Convention date, June 23, 1947. [Class 7(v)] In an engine starter drive including a pinion 3, Fig. 1, adapted to be brought automatically into and out of mesh with an engine member 4 under the control of a nut 21 located on a screw-shaft 8 actuated by the power shaft 1, a driving clutch member 24 rotatably mounted on the pinion 3 and having teeth with inclined torque transmitting surfaces co-operates with a driven clutch member 29, splined for axial movement on the pinion, and having teeth formed with corresponding inclined torque transmitting surfaces, whilst yielding means, such as a spring disc 33, are provided on the pinion for pressing the driven clutch member 29 against the driving clutch member 24 and the latter against an abutment 28 on the pinion. The shaft 1 has a hollow sleeve 5 fixed thereto, whilst the screw-shaft 8, journalled on the sleeve, is made to rotate with the sleeve through a drive spring 11 anchored at one end to the sleeve 5 and at the other end to an overrunning clutch 14, which is mounted on the sleeve and meshes with a similar clutch member 16 on the end of the screwshaft 8. The member 14 maintains the spring under slight initial compression and a thrust washer 18 limits the longitudinal movement of the member 14 in the direction to compress the spring 11. The nut 21 which is rigidly connected to a barrel member 23 has the clutch member 24 secured thereto by lugs. The member 24 and barrel 23 have a thrust connection with the pinion through a washer 27. seated against the pinion abutment 28, the pinion having an extension upon which is rotatably mounted the member 24. The clutch member 29 is splined onto the pinion 3 whilst an antidrift spring 35 is located between the nut 21 and a stop nut 9 on the front end of the sleeve 5. In operation and when the pinion 3 has meshed with the engine gear 4 the axial movement of nut 21 is arrested by nut 9 whereupon the screw-shaft 8 is traversed to the left compressing spring 11 until this movement is arrested by the washer 18 so that the screw-shaft 8, nut 21, barrel 23 and pinion 3 are rotated. The clutch 24, 29 will slip under excessive torque such as that caused by back-firing, and the clutch 14, 16 slips to dissipate the rotational energy of the screw-shaft and prevent rebounding of the parts toward the engine gear. In a modification, Fig. 4, the drive spring and associated clutch are dispensed with and the screw-shaft 42 is fixed to. the power shaft 41; the threads of the screw-shaft 42 terminate adjacent the idle position of the control nut 44 and a re-entry spring 58 is provided to ensure re-engagement of the nut 44 after it has run off the ends of the threads when the pinion and barrel are thrown back to the idle position by the starting of the engine. A thimble 59 surrounds spring 58 and thereby limits its expansion and defines the idle position of the nut 44. A mesh-enforcing spring 62 is provided for pressing the nut 44, which is splined to the barrel 48, against a ring 63 in the barrel so that should tooth abutment occur the spring 62 is compressed until sufficient torque is built up to index the pinion, the toothed clutch 51, 54 being arranged to slip at the torque of normal engagement but to transmit the cranking load without slipping.