Patent GB-533940-A (GB)
Title: Improvements in starting gear for aircraft engines
IPC: F02N99/00
Filed: 1939-11-13
Abstract: 533,940. Turning-gear ; starting. POBJOY AIRMOTORS & AIRCRAFT, Ltd.. and TOWLER, C. O. Nov. 13, 1939, No. 29956. [Class 7 (v)] An aircraft engine is provided with a reception fitting for a starting tool and means associated with the reception fitting whereby manipulation of the starting tool, without the manipulation of any other manual means, turns the engine and also operates a starting spark-producing device, primes the carburetter and effects controlled priming of the induction system. The starting tool may be handactuated or driven by a portable electric motor. As shown, the shaft 16 of a hand-actuated starting tool, Figs. 1 and 2, is adapted to be inserted vertically into a reception fitting 10, Fig. 6, and carries splined members 17, 27 for engagement with splined members 11, 12 in the fitting 10. The member 17 is integral with the shaft 16, which is connected to the shaft 14 having a hand grip 15 by means of members 22, 23 pinned to the shafts 14, 16 and connected by a stiff spring 18 and by a Hooke'.s joint comprising a block 19 having tonques 20, 21 engaging recesses in the members 22, 23. The member 27 slides on a squared portion 26 of the shaft 16 and is normally held in the position shown bya coil spring 31 and by catches 29 consisting of spring-pressed balls or leaf springs. The member 27 can, however, be retracted against the spring 31 and turned through 45 degrees, so that a peg 36 rests in a groove 38 and the tool can be used to turn the engine without actuating the starting devices. In normal operation, when the shaft 16 is inserted in the fitting 10, Fig. 6, the member 27 engages the splined member 11 and is rotated to drive through gearing 40, 41 a pump for priming the induction, system. The pinion 40 is interrupted and the pinion 41, to which a sgring 46 is secured, engages a rack 43. connected to the plunger of the priming pump, so that the plunger is reciprocated by the gear and returned by the spring. When the tool has been turned several times, it is pushed further to engage the member 17 with the splined member 12, the member 27 being arrested by a stop ring 37 so that it rides off the squared portion of the shaft 16 against the spring 31. The shoulder 34 of the member 27 actuates a switch 35 for the starting magneto ; rotation of the tool then turns the member 12, which is connected through a disc clutch 55 and a threaded connection.57 to the shaft 58 of a bevel wheel 59, which moves axially into driving engagement with a bevel wheel on the shaft of the engine to be started. A gear wheel 48 secured on the member 12 drives the starting magneto, and is engaged by pawls 61 which prevent backward rotation of the member 12, so that the clutch 55 slips in the event of backfire. When the wheel 59 meshes with the engine wheel, a cam 60, consisting of a tapered pin mounted eccentrically on the shaft 58, reciprocates a plunger 62, Fig. 9, for actuating a diaphragm pump delivering a priming charge to the carburetter. The plunger 62 bears against the end 64 of a bell-crank 63 pivoted at 68 to a link 67 having slots 69 engaging the teeth of a quadrant on the spindle of the pump, which is also connected to the engine by a slower drive for normal operation.