Patent GB-737338-A (GB)
Title: Improvements in or relating to endless belt conveyor or elevator system
IPC: B65G17/02
Filed: 1953-06-15
Abstract: 737,338. Endless belt conveyers. ROBINS, S. D. June 15, 1953 [July 3, 1952], No. 16398/53. Class 78 (1).  An endless belt supported on cradles running on tracks is driven by an independent endless cable, the cradle-belt assembly including weight-actuated cable-gripping tongs having two - directional gripping action whereby they are adapted to grip the cable in both the upper and the lower inverted run. As shown, a pair of pivoted tongs for engaging the driving cable 11 is formed by two members 29 pivoted at 32 each bolted to a cradle member 26. The pairs of cradle members 26 co-operate with corresponding top members 25 to support the belt 8 at intervals, rollers 28 being provided on the members 26 for running on upper and lower tracks 1, 2 respectively. The rollers 28 cooperate with short ramps 42 arranged on the tracks 1 and in depressions of the tracks 2 in advance of and downstream of the head drum (not shown), the tail drum 7, Fig. 7, and at points on both upper and lower runs in advance of and downstream of any points where it is desired to change the direction of the belt in either a horizontal or a vertical plane so that the tongs can be disengaged from the cable 11 and in advance of these points and re-engaged downstream of these points. In order to effect the disengagement and re-engagement on both upper and lower runs, each tong member has two lobes 33, 34 between which is a recess 35. When the recesses in the two members are aligned the cable can pass freely in and out of the recess. The correct angle between the tong members is obtained on the upper run by rollers 28 rising on the ramps 42 while the tongs are held at a desired elevation by rollers 37 running on straight portions 41 of short tracks 38 after which rollers 37 rise up the inclined portions 40 of the tracks 38 to separate the tongs from the cable. The reverse procedure takes place upon re-engagement. On the lower run the correct angle between the tong members is obtained by rollers 28 falling in the depressions of tracks 2 on the ramps 42 which are arranged to give a reduced gauge for the flanges of rollers 28, so holding the tongs pivot in raised position. After disengagement the gauge of the ramps 42 is widened back to normal to lower the tongs away from the cable on to idler rollers 44. As before, re-engagement of the lower run with the cable is the reverse of the above procedure. The freed cables may then be led off by pulleys 14 adjacent the tail drum 7, similar pulleys 15 adjacent the head drum (not shown) and pulleys 16 adjacent the points where a change in direction of the belt is to take place. As shown, intermediate drive units for the cables may be located at the side of the conveyer at the latter points. These consist of a motor 22 driving grooved drums 20, 21 around which the cable passes helically. Reversing pulleys, e.g. the pulley 12, are provided for the cable at the side of the head and tail drums of the conveyer. When passing over the head and tail drums the belt 8 is flattened, stops 36 on the tong members co-operating with other parts of the tong members to hold the belt rigid in its flattened state and prevent further pivotal movement of the tong members. In a modification, Fig. 10, the belt is driven by a pair of ropes and each cradle member has two pairs of pivoted tongs 51, 52 of similar construction to the tongs 29 of the previous embodiment, the pivots 53 of the tongs being disposed between a flat central portion of the cradle formed by upper and lower members 47, 48 bolted together through the belt, and raised side portions of the cradle formed by extended surface portions 60 of the tong members 52. Surface portions 57 of tong members 51 are bolted through the belt to the upper member 47. Rollers 49 carried by the lower member 48 co-operate with tracks (not shown) in a similar manner to that of the rollers 38 and tracks 38 of the previous embodiment. Rollers 61 carried by the tong members 52 run on the tracks 1 and 2 whose ramps operate similarly to the ramps 42 of the previous embodiment. A stop 62 on each tong member 52 co-operates with other parts of each tong member 51 to hold the belt rigid in its flattened state. In a further modification, Fig. 15, of similar form to the first embodiment, the tong members 29 are modified in that one member has a long recess between two lobes 64, 65 while the other has a single lobe 66 arranged to lie between the lobes 64, 65 in the normal troughed condition of the belt so forming two side-by-side recesses 67. Thus, where the driving cable has off-set upper and lower runs the upper run engages in the other recess. A roller 68 on an extension of the lobe 64 takes the place of rollers 37 of the first embodiment, and a lug 71 on the tong member having the lobe 66 cooperates with a stop 70 on the other tong member to hold the cradle in inverted V-form when disengaged from the cable in the lower run, in addition to co-operating with another part of the other tong member to hold the belt rigid in its flattened state. Rollers 73 are mounted in pairs of one forward, one rearward, on the extremities of the cradle, each pair being carried by a bar 74 which swivels on a vertical pivot (not shown) journalled in a lug 76 on a bracket 72 bolted through the belt to the upper cradle member 25. Ramps are associated with the T-section tracks 1 and 2 to operate in similar manner to the ramps of the first embodiment. The pivots 32 of the tong members in this and the first embodiment may be located more exactly in line with the plane of the belt when flattened by cutting a hole in the belt where each pivot 32 occurs. The pivots 32 may be dispensed with by allowing co-operating parts of the tong members to abut in rocker fashion within holes in the belt. Flanges of the tong members may be passed through the holes and bolted direct to the upper cradle members instead of through the belt.