SOME CURIOUS BREAKDOWNS.
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AVERY interesting and wellattended informal meeting was held by the I.A.E. on October 25th, under the genial chairmanship of Dr. Ormariely. Members had been requested to describe curious breakdowns and to bring along damaged parts to illustrate their remarks. Most of the exhibits related to commercial vehicles, and some of them were eery remarkable.
Mr. Nicholson showed a ball throet taken from a worm drive which, as the result .of faulty lubrication, had seized up, the cage becoming actually welded to the thrust race. As a result of the failure, the worm-wheel teeth were stripped off. Other exhibits included a perforated valve and piston. The .former had .become burnt through; not et the seating, but near the centre .of. the head. In the cake of the piston a
piece broken from the top ring had reached the combustion space, and subsequently, became hammered through the crown, leaving a clean rectangular hole about in. by a in.
Major W. H. Smith remarked upon the fact that trouble was frequently experienced with the breaking of the crossshafts near to the wheels on lorry axles of the full-floating type. It was pointed out that the connection between the wheel and driving shaft was frequently rigid, so that any wobble of the wheel due to worn bearings produced Ilexiire and fatigue fracture in the shaft. He also pointed out that in many designs the thread provided for the nut taking the thrust of the wheel was absurdly fine, and described a neat way of overcoming the nuisance of a loose nut and worn thread by employing a eplit
tapered cone which jammed itself on the thread under the action of an end thrusts Major Beaumont dealt with the question of choked oil filters, and recommended an overflow type, which enabled the pump to maintain the circulation even in the event of the gauge becoming completely blocked up. Several cases were cited of lorry engines continuing to run satisfactorily when e large percentage of water had become inadvertently mixed with the oil in the sump. A curious fact. brought to light in the discussions was that certain weaknesses are peculiar to lorries of one make, others cropping up regularly in other makes. It was suggested that a pooling of information by manufacturers concerning breakdowns . would conduce to greater reliability.