)ouble Engine Life With Chromed Rings
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rHE use of chromium-plated piston ring's • could double the life of an mine when load factors were high, and uadrupIe the life when they were low. his was one of the points made in a aper on piston assemblies for oil engines ue to be delivered by Mr. J. E. Lobinson to the Diesel Engineersand lsers Association in London yesterday. It was not completely clear why plated ings did reduce cylinder-bore wear, but was believed that the chromium face revented the rings from becoming mbedded with abrasive particles. As le chromium prevented ring wear, no ebris was produced to wear the mating irface.
Tests with radioactive chrome had Idicated that there was a transfer of nail quantities of metallic chrome from le rings to the cylinder walls, and that le chrome layer so provided on the ore protected the basic cylinder material -om abrasive wear and corrosive attack. One of the disadvantages of the hrome ring was that, because of its ardness, it could take three or four mes as long to run-in as an unplated amponent. In especially difficult cases, cdding-in had been speeded up by introucing an abrasive powder into the vlinder bore through the intake system. fnfortunately this process was not .7.1ective and led to accelerated wear of se other piston rings.
Much research had been carried out
n this problem and a solution had now een found. This was the Cargraph .eatment, which consisted of applying mild abrasive to the periphery of the hrome ring. The amount of abrasive MS small, and quickly removed from le ring, becoming " lost " in the oil.
Mr. Robinson said that it had no effect n the other rings, or the remainder of le engine.