This case history considers uneven heating of a long extruder barrel.Fig.1.shows an extruder motor,gearbox and barrels.The extruder is used for processing polymer,and heat generated by the process is removed by cooling passages in the barrels.When the passages get fouled,side-to-side temperature differentials occur.The gearbox weighs 50 tons and is bolted to a base plate.It "moved"even with the bolts adequately tightened.When a gearbox moves,unpleasant things happen:couplings wear and lock up,input shafts crack and bearings start to fail.
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