Improvements in belt-tensioning devices for belt conveyors

摘要

958,592. Tensioning endless belt conveyers. MINING ENGINEERING CO. Ltd. Jan. 16, 1962 [Feb. 2, 1961], No. 3980/61. Heading B8A. A belt-tensioning drum 18 is carried on rollers 24 that ride on the sides of a carriage 20 and is constrained to move with its axis at right angles to the line of motion by means of two parallel chains 25 which engage sprockets 27 keyed to a shaft 29 and independently mounted sprockets 28. The chains are attached by eye bolts 32 to a frame 26 carried by the shaft 23 of the drum, the bolts being adjusted to tension the chains and square up the drum initially. A part of the frame 26 which extends outside the loop of the conveyer belting forms a yoke provided with a pulley 33 for engagement by a rope 34 connected to a load-sensitive winch 35 or a gravity tower. In use, the belt acquires a permanent stretch and also stretches elastically in response to changes in the load it carries. Elastic stretch is accommodated by movement of the drum to and fro along the carriage which normally remains undisturbed. But the gradual increase in permanent stretch causes the drum to shift its mean position towards the ganged sprockets 27 until a stop 36 on the frame 36 engages a cross member 37 of the carriage. The drum then shifts the carriage 20, which is slidable in a main framework 11, to a new position in the framework, where it remains until another increment of permanent stretch causes the drum to reposition the carriage. The independently mounted sprockets 28 may be replaced by pulleys and the lengths of chain which run over the independently mounted sprockets may be replaced by wire cables. In a modification, Fig. 6, the chains are attached at one end to the drum shaft or its mountings and at the other end to a yoke 39. The centre of the yoke is connected to the load sensitive winch, gravity tower or the like by a rope 40 which is doubled around a pulley 41 on the carriage.