Patent GB-631096-A (GB)
Title: Improvements in and relating to grabs and the like for discharging, conveying and loading cargoes
IPC: B66C3/20
Filed: 1945-06-12
Abstract: 631,096. Overhead transporters. MARSTRANDER, W. T. June 12, 1945, No. 14805. [Class 78 (iv)] Gear for discharging cargoes comprises a fixed mast having pivotally mounted thereon to move in a horizontal plane a framework on which framework is mounted to pivot in a vertical plane a boom carrying runways which runways are traversed by a grab or other load carrier ; 'and means on the boom for automatically disengaging the grab therefrom so that it may be lowered at a desired point. The grab (Figs. 3, 11). The grab comprises centre bar 9 pivoted at 12a to two other bars i.e. eyed bar 10 and bent bar 11. Over this top end of the bars slides block 13 which carries supporting wheels 14a and catch 15. The block, in the position of Fig. 11, allows the centre bar 9 to swing about 12a but, when the block slides down over 12a, centre bar 9 is held rigid with bars 10 and 11. Movable catch 15, when forced out into the position of Fig. 11 by the movement of the block, contacts the beads fixed on the return haulage rope 29 (see later) and so serves to propel the bucket in the return direction to the right. A fixed catch similarly contacts beads fixed on the outward haulage rope 29 and so propels the bucket to the left. At the lower end of the grab, centre bar 9 is pivoted to links 17a which are pivoted to levers 18. Levers 18 are pivoted to the E-shaped grab frame 5 at 5a and carry rollers 21 which support the grab in the position of Fig. 3. The grab has two scoops 1 which pivot about axis 4 of the frame 5 and is supported pivotally by stays 7 from centre bar 9. A chain 23 links the levers 18 together so that these may be raised relative to frame 5 by a tug on the link 24a. The effect is such that, as shown in Fig. 3, the weight of the grab is normally taken by the wheels 21 and thus the grab is caused to be opened when the wheels 21 are displaced from their supporting rope ; levers 18 pivoting downwardly about 5a and the wheels 14a now taking the weight. Rail runway 26 (Figs. 4, 6). This forms a horse-shoe 25 of upper and lower haulage rails 26, 27 which are supported by struts 50 which are riveted to a framework composed of rings 63 connected by vertical plates 62. Now, mast 96 has (Fig. 4) plates 58 which are fixed to it and are separated longitudinally and horizontally, and over the mast slides a tube formed of a double pair of plates 56, 56a so that the tube slides longitudinally but does not rotate. To the tube 56, 56a is fixed the nonrotatable ring 61 which supports the framework so that the latter may rotate and to this ring 61 a ring 59 is rotatably attached by means of rollers. Ring 59 has internal abutments which slide in the horizontal hollowed spaces between the plates 56a so that the framework may be raised and then secured at a height by rotating the ring 59 about its axis. The framework supports a main stay 53 and the stay is pivoted at 55 to boom 54 which is supported by girder 30 so that the boom may be adjusted in the vertical plane. Rope runway (Figs. 3, 6). Boom 54, and girder 30 form the triangular .points of support of a rope runway which forms an extension of the rail runway 26, 27. The rope runway has four ropes. There are two stationary weight-supporting ropes 33, each of which passes round two sides of the triangle and is then secured at points 34 on the girder 30 ; and there are two moving endless haulage ropes 29, each having a left-moving part and a right-moving part and each of which traverses one side only of the triangle between pulleys 84 and 40, the latter being driven from a motor by sprockets 44. On these haulage ropes 29 are driving beads 80 which engage either the fixed catch 22 or the movable catch 15 of the grab whilst the support ropes 33 engage the rollers 14a and 21 of the grab so that the latter is respectively propelled either forwards or backwards from or to the rail runway. Grab discharge sleeve 87 (Fig. 3). Frame 90 is supported between the two ropes 33, and has a longitudinal part 89 between spacing parts 93 and a discharge sleeve 87 swiveling at 87a. The sleeve has a counterweight 87b and a lateral ramp 87c and a fin 87d so that, when the grab comes from the right, its wheels 21 ride the ramp and the grab is tipped and its wheels 21 and levers 18 fall to open and discharge the grab. The frame 90 is resiliently held at 88 by rope 88a (not shown) from the boom 54 so that the frame will yield. Derrick (Figs. 4 and 14). The grab is hoisted by hook 103 depending from pulley 101 which is raised by winch rope 100. Additionally, the derrick 68 itself is raised by means of rope 109. Lift-cham 70 is attached to the derrick and passes through the check 72 (Fig. 4). The check 72 includes a rotatable inner tube 73 and a split outer tube 72 and a wedge 74 is pivoted on the inner tube 73 and is operated by handle 76 which is locked in position by being rotated to bear against cam surface 72b on outer-tube 72 and which thus serves to lock the chain as an additional safeguard lest the derrick fall. Operation. The empty grab being on the runway at the horseshoe end with the levers 18 in their lower position and the grab scoops open, the hoisting hook is inserted first through the ring 24a of chain 24 and then into the eye in bar 10, and the grab is then lifted off its rails 26, 27. The grab is lowered by the hook till the grab strikes the bottom of the hold containing material for discharge when the hook slips out of the eye 10 but retains ring 24a and the hook is then lifted. This first causes the tension on the chain 24 to raise levers 18 and so to close the grab jaws having material between them, and then lifts it till it perches on the rail runway 26, 27 with its levers 18 in their raised position supported on lower rail runway 27 the ring 24a being then dropped over bar 10. From there the grab runs by gravity on wheels 21 over the switches 46 on to the rope runways 33. In this position the catch 22 meets a bead 80 on the lower left-moving haulage rope 29 to propel the grab to the discharge sleeve 87 where it rides up the ramp 87d. Wheels 21 then slip off the sleeve and swing downwards and so open the grab jaws and discharge material. The weight is transferred to block 14 which moves upwards relative to the centre bar, and catch 15 is thus forced out and meets a bead 80 on the upper right-moving haulage rope 29 and returns the grab empty along the upper rope 33 with levers 18 in their lower position to its original point. Automatic release hook (Fig. 13). This may be used on the runway in place of the grab when the load is a case which is to be suspended. It is formed similarly and comprises a centre bar 115, 116, pivoted shanks 114 mounting wheels 117 and carrying hooks 114a so shaped that the rope suspending the case will easily slide thereoff.