Patent GB-483912-A (GB)
Title: Improvements in crane hoisting apparatus for lifting floating objects
IPC: B63B21/16
Filed: 1936-10-22
Abstract: 483,912. Attaching loads to crane ropes; winches. NORMAN. A. G. B. Oct. 22, 1936, No. 28718. [Classes 78 (iv) and 78 (v)] [Also in Groups XXIV. XXV, and XXXIII] In crane hoisting-apparatus, particularly for raising aircraft from the sea, a pilot rope is attached to the load and the hoisting rope subsequently lowered and automatically coupled to the pilot rope at a point adjacent the load. Means are provided which automatically pay out the ropes or take-up slack according to the movement of the aircraft relatively to the apparatus due to movement of the water. In the arrangement shown in Figs. 6 and 7, the hoisting rope is provided with a hook 127 which is pivotally mounted on a ponder ball 125 between a pair of plates 124 and held in the position shown in Fig. 6, against the action of a spring 129 by a lever 130 provided with a projection 131 engaging an abutment 132 on the hook. When the hook 12] on the pilot rope has been engaged in the hoisting ring 137 of the aircraft, the hoisting rope is lowered. As soon as the end of the lever 130 touches the ponder ball 120 of the pilot rope, the hook 127 is released and springs to the position shown in Fig. 7. An element 133 on the hook engages a locking lever 134 so as to imprison the ball 120, the shank 119 being accommodated within a slot 128 in the hook. Winding mechanism to effect the necessary movements of the ropes is shown in Figs. 1 and 2. The drum 10 of the hoisting rope is coupled to a shaft 12 which is rotated by the main hoist motor on engagement of a clutch 13 comprising parts 25, 26. The part 26 is keyed to the shaft 12, and the part 25 associated with a spur wheel 28 which is rotated by a worm wheel 29 mounted on a shaft 30 driven from the main hoist motor. A spring 32 urges the part 26 into contact with the part 25, but such contact is normally prevented by a sleeve 36 controlled by a spring 37. This sleeve is moved to permit engagement of the clutch by a lever 39 connected with a rod 41 engaging in a recess 38 on the sleeve, the parts 25, 26 being held in contact by spring-controlled pawls 44 which engage behind the sleeve. The drum 11 of the pilot rope is driven from a motor 14 through a differential 15. A spur wheel 16 associated with this differential constantly meshes with a pinion 17 which is slidably mounted on a shaft 18 coupled with a re-winding motor 19 through a slipping clutch 20. The motor 19 runs continuously while the clutch 20 is adjusted so that it will grip sufficiently to wind in either or both the hoist and pilot rope, but will slip as soon as any appreciable weight is put on either rope. With the clutch 13 disengaged, the pilot rope is first lowered by the motor 14 and hooked on to the plane, and the motor then reversed to haul the rope taut. The main rope is then lowered by the continued running of the motor 14 until it is automatically coupled to the pilot rope as described above. The motor 14 is then reversed and the pilot rope lowered slightly to permit the clutch 20 to engage and the motor 19 to haul taut the hoist rope. The lever 39 is then moved to position (2) to allow the parts of the clutch to contact and then to position (3) to cause the part 26 to be disengaged from the motors 14, 19 and to be coupled to the main hoisting motor. The clutch 13 is adjusted so that it can only engage positively when the plane is on the crest of a wave. Fig. 4 shows an alternative mechanism in which clutches 55, 56, 57, 58 are disposed between the re-winding motor coupled to a shaft 54, and the pilot rope drum coupled to a shaft 53, and a differential unit 62 is provided which is geared to both the sliding and fixed parts 71, 73 of a clutch 66 associated with the main hoist shaft 52 and geared with the shaft 75 driven by the main hoisting motor. These clutches, together with a friction clutch 72, are operated by a control lever on a shaft 76 through levers actuated by cams on the shaft 76 and on a shaft S6 geared to the shaft 76. When the pilot rope has been lowered and secured to the plane and the clutch 56 engaged so that the wheel 61 of the differential is driven from the re-winding motor, all the movements of the plane are transmitted by the pilot rope to the main hoist rope. The hoist rope is then lowered by the hoist motor so as to be automatically coupled to the hook on the pilot rope, the drive from the driving shaft 75 being transmitted through the differential and gearing 64, 67, 68. The clutch 66 is then engaged for hoisting, the clutch. being so constructed that it will only engage positively when the plane is on the crest of a wave.