Patent GB-832860-A (GB)
Title: Parachute release device
Inventor: COLT RUTGER BARCLAY
IPC: B64D17/54
Filed: 1957-11-19
Abstract: 832,860. Spring power-storing mechanism. BENDIX AVIATION CORPORATION. Nov. 19, 1957, No. 36031/57. Class 10. [Also in Groups XVIII and XXXIII] A parachute release device wherein the rip cord is wound on a spring-powered drum which, when released, winds in the rip cord to deploy the parachute, comprises timing means including a member rotatable with, and also relatively to, the drum, latch mechanism carried by the drum and member to latch the drum to the member when the drum has been rotated through a predetermined are in a direction to wind the spring, escapement means which when released is set in motion by the torque exerted on the member by the spring, and means which automatically trips the latch mechanism to free the drum from the member to wind on the rip cord when the drum has rotated through a predetermined arc under the control of the escapement during a preset time delay period. In Fig. 1, the rip cord 16 is wound on to a drum 17 mounted on a fixed shaft 19. A coil spring 20 is secured to the drum and to part of the fixed housing 24. Also mounted on shaft 19 are an annular member 27 having an arm 27<1> ending in a head 28 adapted to contact a face plate 40<11> on shockabsorbing material 40 on a fixed stop 40<1>, a gear sector 29 with teeth 30, and a plate 37 supporting a pin 36 and angularly adjustable by a screw 38 in a fixed post 38<1> (see Fig. 2). A boss 39 on the drum is normally retained between a pin 41 on gear sector 29, and the tooth 33 of a pawl 32 mounted on a pin 31 on the gear sector. A spring 35 on the sector biases the tooth 33 towards shaft 19, and presses a cam face 34 on pawl 32 against pin 36. The escapement comprises a disc 54 on a shaft 55, urged to a neutral position by a spring 55<1> connected between a fixed point and an eccentric point on the disc. A slot 56 has step faces 56<1>, and a shaft 59 extending through the disc bears an arm 58 having a pin 57 co-operating with the steps 56<1>, and a latch 62. Shaft 59 is connected through gear 61, gear train 60, gear 50, a one-way clutch 52, and gear 47 to the teeth 30 of sector 29. The escapement is normally restrained by a lever 71 in the path of latch 62, this lever being withdrawn by a spring 72 on withdrawal of a manual arming pin 73. To prevent operation of the device above a desired altitude, a helical cam 63 is disposed in the path of latch 62, and is adjusted vertically by a stack of aneroid capsules 66, and adjustable angularly by a knob 68 having a scale 69 read against a pointer 70. The altitude at which the capsules withdraw the cam 63 from the path of latch 62 is thus preset by rotation of knob 68. Should the (evacuated) capsules develop a leak, the resultant excessive expansion is transmitted through groove 74, crank 75, and cam face 77 to a lever 78, and indicated on scale 80. In operation, drum 17 is rotated anticlockwise (Fig. 2), to wind the spring 20, until boss 39 engages pin 41, tooth 33 then being moved by spring 35 to engage the boss, and lock the drum and gear sector 29 together. The gear sector is also rotated anticlockwise to a datum position indicated by a finger 43 on the sector and a painted area 44 on a base-plate 11. The one-way clutch 52 permits relative movement between gears 47, 50 during this setting operation. The length of the time delay as indicated by a scale 45 and datum 46 is set by rotating plate 37 and pin 36 by screw 38. When the manual arming pin 73 is withdrawn and the device is below the altitude set by knob 68, the arm 58 is free to rotate, and does so under the torque exerted by spring 20 through the gear sector 29, and gears 47, 50, 60 and 61, at a rate determined by the reciprocation of disc 54. The gear sector 29 and drum 17 thus rotate slowly until pawl 32 is deflected by the stationary pin 36, freeing boss 39. The drum then rotates freely pulling rip cord 16, until boss 39 engages arm 27<1>, urging head 28 against the shock absorber 40. The spring 20 thus only partially unwinds. To reset the device, the spring is rewound to engage boss 39 between pin 41 and tooth 33, a winding tool being used.