Patent GB-121951-A (GB)
Title: Improvement in Stop Gear for Aeronautical Engines.
Inventor: DOUGLAS THEODORE
IPC: H01H35/14
Filed: 1918-12-23
Abstract: 121,951. Douglas, T. Dec. 27, 1917, [Con vention date]. Controlling motive power automatically. - A pendulum device for attachment to aircraft to stop the motor in case of accident by short-circuiting the magneto comprises a casing 12 carrying a bracket 22, Figs 1, 5, and 9 from which a pendulum-bar 11 is suspended, and knobs 25 by which connexion is made to circuits 9, 10 leading to the magneto and earth respectively. These circuits are connected up to a switch 5, which may be operated to short-circuit the magneto by hand, and are connected by any undue movement of the bar 11. The casing 12 is generally placed in a plane at right-angles to the axis of the motor, or in a position such that, owing to any abnormal vibration due to unbalanced forces, the bar 11 can move. One knob 25, Figs. 1 and 4, is connected by bars 26 and spring brushes 27 on the underside of the cover of the casing to brackets 23 mounted within the casing which are engaged by spring brushes 24 carried on the bar 11 when it moves. The other knob 25 is connected to a central contact 28. A switch 29 mounted on the casing is provided with a spring brush 27 beneath the cover which makes contact with the bracket 22 when the switch is moved to engage the contact 28. When an abnormal movement of the bar 11 takes place, the current from the circuit 9 passes through one of the bars 26, a brush 27 to one of the brackets 23, then up the bar 11 through the top brush 27 along the arm 29 to the contact 28, and bar 26 leading to the other knob 25, and then to the earth circuit 10. To ensure a permanent short-circuit, spring-controlled clutches 34, Fig. 8, of insulating-material with metal insets are provided to lock the bar 11 in its deflected position. The clutches are released by spring plungers 38. The bar 11 is held normally in its central position by one or two compression springs 42, Fig. 5, and adjustable springs 46 in tension, and has a projection 45 to permit handoperation, and a pin 31, which moves in a groove 30, Fig. 1, and shows the position of the bar 11. A mark 52, Fig. 4, of visible paint, shows when the lever 29 is in its operative position. The casing 8 may be placed parallel to the crank-shaft to stop the motor, say, in the case of a collision. or two casings 8 may be used. In a modification shown in Fig. 10, a pendulum 54 is suspended by a flexible connexion and abuts at its upper end against a bearing member 61 which is connected to earth. The lower end of the pendulum 54 engages a recess in a head 55 on a stem which is forced up by a spring. A conductor 53 surrounds the rod 54 and is connected to a circuit 9. An abnormal shock in a longitudinal or transverse direction will displace the rod 54, and the insulation 59 around the head 55 will, when it rises, press the rod 54 against the conductor 53 and short-circuit the ignition system. The apparatus may be used to open the main circuit. The Specification as open to inspection under Sect. 91 (3) (a; comprises also the modifications, shown in Figs. 13 (Cancelled), 14 (Cancelled). 15 (Cancelled), and 17 (Cancelled), wherein a single shock is arranged to break both secondary coils of the two engines of an airship. Two pivoted elements 74 normally engage two spring- controlled catches 75 until disengaged by contacts 80, 81 on the rod 11 engaging " bevel " surfaces on the element 74. The supports of the spring-controlled catches are connected to two binding posts 25 on one side of the casing, Fig 13 (Cancelled), and the supports of the elements 74 are connected to two posts 25 on the other side. The method of connecting up the distributors 83 to the secondary coils 82 through the casing 8 is shown in Fig. 17 (Cancelled). A further modification is described wherein a single catch such as 34 is arranged over the bar 11 to control twinengined machines. This subject-matter does not appear in the Specification as accepted.