GB323359A - Improvements in grabs - Google Patents

Abstract

323,359. Page, M. W. Flood-, and Westwood & Co., Ltd., J. Dec. 21, 1928. Grab-buckets.-Relates to grabs comprising a main frame 1 with buckets pivoted thereto at 6 and connected with a sheave-block 3 by locking-mechanism which is released by a triggerlever 24 engaging over a suspended ring 25, the locking-mechanism being re-engaged when the buckets rest upon the ground, as shown in Fig. 6, with the locking device below the frame 1. To reduce the overall height, when the block 3 is lowered in the guides 2, the trigger-lever 24 is turned into an approximately vertical position, so that it may pass below the upper lever of the frame 1. As shown, the locking device comprises a sleeve 9, Fig. 3, carried by the block 3, engaging over a vertical pin 10 and provided with a horizontal pin 11 which may be turned on its axis for locking and unlocking the sleeve 9 on the pin 10. The pin 10 is mounted on a block 14 connected with the buckets by links 15, and is kept vertical by a tail-rod 17 sliding in a block 18 connected with the buckets by links 19. The buckets are also steadied by outside links 20 connected with a slide 21 moving in the guides 2 at one side of the grab. The pin 11 is provided with a weighted arm 30 having a contact surface 31 engaged by a counterweighted lever 22 loose on the pin. This lever is connected by a link 23 with the trigger-lever 24 which is also carried by the block 3. An extension 26 of the, lever 24 forms a counterweight and is provided with a bearing surface 27. When the block 3 is lowered in the guides 2, the surface 27 meets an abutment 28 on the guides and the trigger lever 24 is turned downwards so as to pass the frame 1. With the open buckets resting upon the ground, the block 3 is lowered to bring the sleeve 9 over the vertical pin 10 and the horizontal pin 11 is turned automatically into the locking position by the weighted lever 30. When the block 3 is raised the buckets are closed as shown in Fig. 1, and if the trigger-lever is raised through the ring 25 and the grab is then lowered, the levers 24 and 22 are raised and the lever 22 engages the part 31 to lift the lever 30 and release the pin 10 allowing the buckets to open. To permit opening of the grab by lowering it on to the ground, the counterweights 26, 32 on the, levers 24, 22 may be made to overbalance the weighted lever 30. The pin 11 will then be released as soon as the weight of the buckets is supported on the ground leaving the pin free to turn, and the parts will be re-engaged automatically as described above, since in the position shown in Fig. 6, lever 22 is held away from the part 31. The opening of the buckets when suspended in mid-air is cushioned by a dash-pot 7.