GB572780A - Improvements relating to towing and release mechanism - Google Patents

Abstract

572,780. Rope fastening and releasing devices. MALCOLM, Ltd., R., and LOBELLE, M. J. O. April 6, 1943, No. 5506. [Class 44] [Also in Group XXXIII] A towing and release device, particularly for aircraft towed initially by two tug craft one of which is disconnected when the aircraft has become airborne, comprises a coupling device in the towing cable which passes through a plug member h on a junction member d, connected to the aircraft to be towed, a relaxation of the pull by one of the tug craft causing the cable to be drawn through the junction member by the other tug until the member h engages and releases the coupling, further movement through the junction member of the cable attached to the remaining tug craft being prevented by an enlargement on the cable which engages the end of the plug member. The device may be used in towing marine vessels when it is desired to release one tug at short notice. In one form, the coupling comprises a casing 20, Fig. 5, attached to the cable from the auxiliary tug craft, and adapted to receive a spigot u attached to a cable g which passes around a sheave v, Fig. 8, in a junction member d connected to the towed aircraft by a forked bridle. This cable is connected at its other end to the main tug craft. A plug member h through which the cable passes is pivoted to the member d. Normally an enlargement 24 on the spigot u is engaged by two pivoted and statically balanced pawls 21 urged into engagement with the enlargement 24 by springs 23. To release the auxiliary tug craft it is throttled down, whereupon the main tug draws the cable g around the sheave v until the plug member h enters the lower end of the casing 20 and forces apart the pawls 21. The casing 20 then falls away and the spigot u remains in contact with the member h. A stop on the other leg of the cable prevents it from being drawn too far over the sheave v in the other direction. Terminals 14, 15, the latter insulated enable electrical connections to be effected across the coupling. The ends of the cables attached to the two tug craft are readily releasable as also is the bridle connected to the towed aircraft. In another form, Fig. 10, the casing of the coupling is in two hinged parts having ledges 33 for retaining a disc 34 secured to the end of the cable g, and grooved projections 36 for engagement by the undercut head of a member 37 This member has a sliding thimble 40 urged by a spring 41 against the undersides of the projections 36. When the plug member h engages the lower end of the member 37 the latter is moved out of engagement with the projections 36 and the hinged halves of the casing are forced apart to release the disc 34. Simultaneously the thimble 40 is moved by the spring 41 to close the undercut surface of the head 37 to prevent the projections 36 from re-engaging the head 37 as the casing falls away.