Patent GB-1044762-A (GB)
Title: Improvements relating to parachute connectors
IPC: B64D17/38
Filed: 1962-05-08
Abstract: 1,044,762. Hooks. HARLEY PATENTS (INTERNATIONAL) Ltd. April 30, 1963 [May 8, 1962], No. 17728/62. Heading F2H. [Also in Division E2] A parachute connector which is arranged to interconnect a parachute and a cargo comprises a part 10 to which the parachute is adapted to be connected, the said part being mounted on a body for limited relative movement thereto from an initial position to a second position when a shear connection 50 between them is broken on the application of a first predetermined load, a hook 13 pivoted to the body for securing the cargo, a member 20 also pivoted to the body and which normally retains the hook in an engaged position as a result of the weight of the cargo on the hook but which is arranged to be pivoted by a spring 30 to a release position when the load on the hook falls to a second predetermined value, e.g. on hitting the ground and a spring-biased safety catch 33 pivoted to the body and which by engagement between the member 20 and the part 10 in the initial position blocks movement of the pivoted member 20 but which when the second position of the part 10 is reached can be spring- biased clear of the member 20. In the construction shown, the body comprises two plates 12 which are spaced-apart and the plate 10 has a pair of slightly elongated openings 45, 46 which co-operate with pins 47, 48 extending between the plates 12 so that the plate 10 is slidably connected with the body. The hook 13 is mounted between the plates 12 on a pivotpin 14, the hook in its fastening position closing open-ended slots 16 in the plates 12. The member 20 is a lever which is biased by the spring 13 to the position in which the hook is free to rotate to its unfastening position. The hook is provided with a projection 28 which engages a notch 26 in the lever 20 and so long as the cargo is being supported by the hook the engagement of the projection with the notch prevents the lever 20 rotating to its releasing position. The safety catch 33 is pivotally mounted between the plates 12 on a pivot-pin 36 and in the position shown it prevents the lever 20 moving to its releasing position and is itself prevented from movement by engagement with the lower end of the plate 10, the plate 10 being held in this position by the shear wire 50. When the cargo and parachute are first dropped from the aeroplane the connector is in the condition shown and when the first predetermined load, e.g. 400 lbs. is exerted on the connector by the parachute commencing to open the shear connection breaks and the plate 10 slides relatively to the plates 12 and releases the safety catch 33; this is then rotated to the position in which it releases the lever 20 by the spring 30 and since the pivot-pin 36 is near one end of the safety catch and the spring 30 acts on a pin 32 near the pivot-pin the safety catch takes approximately half-asecond to move to the position in which it releases the lever 20 and by then the parachute is open sufficiently to prevent the load on the connector dropping to zero if the cargo swings. The hook 13 therefore remains in its fastening position since the projection 28 holds the lever 20 from movement. When the cargo reaches the ground the spring 30 is able to rotate the lever 20 to the releasing position when the force on the hook falls below 20 lbs. and the hook can then release the cargo. In a modification, a shear pin is used instead of the shear wire shown and this pin does not shear until a force of 3000 lbs. is exerted on the connector. In this construction there is no projection on the hook or a notch in the lever and instead friction is relied upon to retain the lever and hook in engagement. To retain the shear pin in position, rotatable cover-plates are provided on each of the plates of the body and these have apertures so that in one position the shear pin can be inserted and in another position its removal is prevented.