THE equipment illustrated was used by R. W. Avery and J. G. Hoffman, of General Electric Company, Erie, Pa., to investigate the problem of cylinder liner scuffing, and their results were presented in a paper to the ASME's Diesel and Gas Engine Power Conference at Chicago, 23–27 April, 1967. The liner specimens were cut from full size cylinders and ring segments, one inch long, were cut from full size rings and mounted rigidly so they could not tip. The feature of this rig is that the liner slope and curvature provides four different lubrication conditions for each test, and practical operating conditions were very well simulated. Loads, simulating ring loads, to a maximum of 5,100 p.s.i. were applied through an expandable ring carrier. The higher loads were above normal operating values, but were used to approximate imperfect ring and liner fit, as might occur during break‐in or with liner temperature distortion. Water cooling on the outer side of the liner maintained gross temperatures at values observed in operating diesel engines. Speed was constant at 650 r.p.m. making average surface speed 325 ft/min. and maximum speed 510 ft/min. Ring and liner temperatures were measured, the point of measurement of the former being 0.020 in. back from the contact face and in the latter 5/16 in. from the liner inner surface. Friction between a pair of rings and their liner was measured by a strain‐gauged transducer at the top end of each liner and was recorded by an oscilloscope and camera. Ring contact or loss of full oil‐film support was measured by electrical continuity of a 15 v. 50‐microamp. limited circuit.