THIS paper presents numerous charts showing the wear of cylinder and piston rings. Attention is called to the fact that maximum wear usually is found in line with the top ring at the upper limit of its travel. This is attributed to the presence of dirt and to the high temperatures which make lubrication difficult in this region. Reasons are given for believing that the piston rings are more often the agent producing wear, than is the piston.
Special experiments are described which illustrate the effect of insufficient oil, of abrasives, of rough surfaces and of high local temperatures. It is concluded that inadequate lubrication, but not necessarily insufficient lubricant, is the primary cause of wear.