GB630513A - Improvements in engine starter drives - Google Patents

Abstract

630,513. Turning-gear. BENDIX AVIATION CORPORATION. April 21, 1947, No. 10559. Convention date, May 20, 1946. [Class 7 (v)] In an engine-starter drive comprising a power shaft 1, Fig. 1, a pinion 8 slidably journalled thereon for movement into and out of mesh with a gear 9 of an engine to be started, means actuated by rotation, of the power shaft for moving the pinion into mesh with the engine gear including a control nut 13 screw threaded on the power shaft so as to be axially slidable therealong, a driven-clutch member 18 fixed to the pinion, and a driving-clutch member 16 frictionally co-operating therewith, there is provided means including an elastic pressure and torquetransmitting member 15 connecting the control nut to the driving-clutch member for imparting axial thrust to the clutch and transmitting torque to the driving-clutch member as well as stop means, such as spacing member 25, for limiting the thrust applied to the clutch to thereby limit its torque-transmitting capacity. Rotation of the power shaft 1, due to energisation of a starting motor causes the nut 13 to traverse a screw shaft 5 which is fixed to the power shaft by a pin 7, until the pinion 8 meshes with the engine gear 9 and abuts a thrust ring 4. Further movement of the nut 13 compresses the elastic pressure and torque-transmitting member 15, which is seated between the knurled faces of a flange 14 on the nut and the driving-clutch member 16, and forces the latter into engagement with the driven-clutch member 18 that is secured by brazing or welding to a radial flange of the pinion 8 and formed with a skirt which is slidable over a plain portion of the nut. When the engine starts, acceleration of the pinion 8 causes the nut 13 to thread itself back along the screw-shaft 5 to the idle position, with the assistance of an anti-drift spring 34, which latter is located between the rear inturned flange 35 of a barrel 22 and a shoulder on a sleeve 31 that is slidable on the screwshaft 5. Just before the nut 13 runs out of the threads on to a plain part of the screw-shaft the nut flange 14 abuts the sleeve 31 thereby compressing a re-entry spring 32, which is located between the sleeve 31 and a further sleeve 28 also slidable on the screwshaft 5. After the momentum of the nut 13 has been dissipated, the re-entry spring 32 urges the nut into initial engagement with the threads of the screw-shaft 5. If the starter is operated when the engine gear 9 is rotating backwards, damage to the former is avoided by limiting the torque capacity of the clutch 16, 18 by means of the spacing member 25 interposed between the pinion flange and the forward edge of the nut 13 which prevents further longitudinal movement of the nut after a space 26 has been taken up as a result of the compression of the elastic member 15 ; oil impregnated washers are placed between the contacting surfaces of the stop means. In a modification, Fig. 4, the screw-shaft 45 is in two parts which are connected by a tooth clutch 46, 47. The two sliding sleeves are dispensed with and one spring 62 located between a rear-inturned flange 61 on the casing 58 and a driving head 48, serves both as an entry and anti-drift spring. The meshed position of the pinion 43 is defined by abutment of the flange 61 and the driving head 48, which latter embodies the driving clutch member 47 and is pinned to the power shaft.