Patent GB-582800-A (GB)
Title: Improvements in automatic release-links for parachute-borne loads
IPC: B64D17/38
Filed: 1944-01-26
Abstract: 582,800. Fastenings for parachute-borne loads. COOPER, D. W. Jan. 26, 1944, Nos. 1472 and 22818. [Class 44] [Also in Group XXXIII] In an attachment device for parachuteborne loads released when the load reaches the ground, a shackle member is releasably held in the device by a rotor slotted to receive the member, rotation of the rotor to locking position carrying the member over the deadcentre so that the tension of the load holds the rotor in locking position against the action of springs biassing the rotor to release position, and operating to release the shackle when the load-tension is removed.. During the period between launching and the load becoming airborne, the rotor is held against release by a time-controlled device. As described, one end of a chain 31 is permanently pivoted to the body of the device at 32 and its other end has a T-headed member 35 pivoted thereto by pin 58. The chain may be passed through shackles 29, Fig. 6 secured to the ends of rigging lines 30 of a number of parachutes, the chain preferably being of a kind which can be flexed readily towards the device but in the opposite direction opens out only to straight form so as to be readily withdrawn from the shackles. The rotor is a mutilated cylinder having an open longitudinal slot 22 with seatings which receive the cylindrical head 34 of member 35, the shank of which is accommodated in a transverse recess intersecting the longitudinal recess. The body 12 of the device is of generally cylindrical form having upstanding lugs 11 at one end between which the rotor is trunnioned block springs 14 bias the rotor towards release positioning (anticlockwise in Fig. 2) the springs being set by cocking levers 21 which can be adjustably connected to the spring cover-plates 16 by pegs 20 selectively engaged in one of a number of holes in the cover-plate, so that the initial angular setting of the lever may be varied to vary the tension of the springs when the levers are rotated. Slidable within the body 12 is a cylinder 47 to which the load-receiving shackle 46 is connected. Within the cylinder is a fixed piston 40 with packing ring 48. The piston is removably held by spring-plunger gudgeon pins 42 passing through slots 41 in cylinder 47 and into apertures in the wall of body 12. The piston has a valve 53 allowing ready passage of liquid in one direction, but slow passage in the other, to provide the time-controls retarding the outward movement of cylinder 47 under pull of the load. The inner end of the cylinder has a projecting stop 28 with arcuate end 39 adapted, when cylinder 47 is pushed inwards, to enter a recess cut in the slotted portion of the rotor, to hold the rotor against rotation from the locking position shown until the cylinder 47 has been withdrawn by the pull of the load. The stop forms an abutment for the bottom of the transverse slot to prevent anti-clockwise rotation of the rotor, and for claws or shoulders 25 to prevent clockwise movement. In use, the free end of the chain is passed through the shackles 29, and the member 35 is then positioned with the projecting ends of pin 58 resting in slots 59, the head and shank being swung into the slots of the rotor. The pin 58 in slots 59 controls the direction of pull on the chain. The rotor is then moved to locking position, the cylinder 47 pushed in to engage the stop 28 in the rotor slots, and the springs are set to the desired tension. A modification (seen in Fig. 6) the body of the device is formed of a pair of spaced parallel plates 102 secured by bolts 63, the working parts being mounted between the plates. The rotor is held against release by an arm 70 thereon engaging a quadrant 83 which is slowly rocked clear of the arm by link connection 95 with a compression spring plunger having a rack (not shown in Fig. 6) engaging the first of a train of gear wheels ending in an escapement device. The quadrant is held against release movement until the load becomes airborne by a projection 86 on a plate 79 engaging behind a projection 87 on the quadrant. The plate 79 has slight rocking movement about the axis of the rotor and is normally biassed clockwise by a plate spring 82 so that the projection 86 lies in the path of the projection 87. The T-bead of the terminal chain member is seated in a slot 71 in the rotor, which is then rotated clockwise to bring arm 70 to the left of the quadrant and at the same time engage the projecting ends of the pivot pin by which the terminal chain member is mounted into engagement with a slot 78 in the plate 79. The plunger is then pushed in to bring the quadrant behind arm 70 and snap projections 86, 87 into engagement. The pull on the chain when the load becomes airborne rocks plate 79 anti-clockwise to disengage projections 86, 87 and allow the quadrant to be withdrawn slowly by the plunger. The springs biassing the rotor to release position are housed in drums 98 rotatable to tension the springs by levers 103 adjustably connected to the drums and retained in the tensioning position by catches 106. Levers 103 have upstanding webs of tapering form to provide leads preventing fouling of the lines with the drums.