Patent GB-408785-A (GB)
Title: Improvements in impulse driving mechanism
IPC: F16D5/00
Filed: 1933-02-25
Abstract: 408,785. Impulse driving-mechanism. BENDIX AVIATION CORPORATION, 105, West Adams Street, Chicago, U.S.A. Feb. 25, 1933, No. 5780. Convention date, Feb. 27, 1932. [Class 80 (ii).] In an impulse driving- mechanism, more particularly for a magneto, an impulse - controlling pawl 40 is maintained in the non- engaging position above a predetermined speed by a spring-pressed latch 46 which is releasable either manually, or automatically in response to a reduction in speed of the driven member. Keyed to a driven shaft 2 isacup-member 6, the outer flange of which is permanently connected with a freely-rotatable driving-member 12 through a pair of spiral springs 15. The impulse-controlling pawl 40, pivoted on a fixed spindle 44 is pressed by a torsion-spring 43 on to the driven-member 6 which is provided with diametrically - opposite cam - surfaces having steep shoulders 30 for abutting on the pawl 40 and checking rotation of the drivenmember to allow the driving-member to continue and store energy in the springs 15. The pawl is periodically lifted from the shoulders 30 to allow the springs to deliver an impulse to the driven-member, by means of diametricallyopposite cam-surfaces 33 or the driving- member 12. The relative movement is limited by abutment of facial shoulders 34 on the driven member against the steep rear ends of the cams 33. When the speed increases beyond a predetermined value the increased ejecting-force of the cams 33 throws the pawl 40 further outwards to be held in an inoperative position by the latch 46. To release the pawl 40 this latch 46 can be directly withdrawn manually, or automatically by means of a cam 59, pivoted between the bifurcations of the pawl 40. At low speeds the cam 59 is moved downwards, against the resistance of a torsionspring 62, to hold back the latch 46, this movement being effected by means of a spring- returned centrifugal arm 64 pivoted on the driven-member 6 and having a nose 65 projecting therefrom to engage a foot 71 of the cam 59. Increase of speed swings the arm 64 outwards to retract the nose 65, so releasing the cam 59 and allowing the latch 46 to resume the obstructing position. Additional safety-means ensure that the pawl 40 shall not return to the operative position at normal speeds even if the latch 46 has been manually released. These comprises two pairs of arms 75, 78 pivoted on the driven-member 6 to fly out centrifugally through the periphery of the driven-member and fill in the cut-away cam-surface in front of the shoulders 30 thereby rendering them ineffective. The outer ends of each mainspring 15 are attached at diametrically-opposite points to the driven-member 6 by engaging its bent-over ends with short plates riveted to the driven-member. The inner ends of the springs are bent over through open-ended slots in a sleeve 18 welded to the driving member 12. Both bent-over ends are accommodated in grooves such as 23 in the members to permit easy detachment and the springs are separated by a partition 16 having radial lugs engaging grooves in the driven-member 6. The end of the centrifugal arm 64 bears on the sleeve 18 through a non-metallic roller 69. The member 12 is driven by means of claws 10, 11 which project from its face.