Cylinder Liners which Can be Hardened.
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OWNERS of large fleets of commercial vehicles have for a long time feltthot the usual method of overcoming cylinder wear—i.e., by grinding out the bores and fitting oversize pistons— is not always satisfactory, due to the complication caused by the necessity of stocking several sizes of piston varying within narrow limits. Great care also has to be taken in such circumstances, when overhauls are being carried out, to ensure that the mated pistons and cylinders are refitted after dismantling.
To circumvent these disadvantages, worn cylinder bores are, nowadays, often enlarged and relined to bring them fo their original diameter, and in this connection it is interesting to note a new development of the Andrews Crankshaft and Cylinder Co. The liners manufactured by this concern are actually sand cast
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jugs of special material which, when heat treated, can he hardened to give a Brinell figure of 480 to 480.
The liners are quite soft before the hat treatment, and as they do not distort unduly during this process, they can be machined to within very narrow limits of the required sizes, both as regards internal and external dimensions. When finished the iron is hard all the way through and is impervious to attack by a file.
One of these Resistwear liners, as they are called, has covered over 30,000 miles in a bus engine, and now only shows .0015 in. wear. The piston —a Hardalloy aluminium type, which is another product of ther Andrews Crankshaft Co.—had suffered barely measurable wear. Inquiries should be addressed to the Andrews Crankshaft Co., whose address is 312, Bradford Street; Birmingham.