Study on Friction and Wear Characteristics of Low-SAPS Diesel Engine Oils(DEPARTMENT OF MECHANICAL ENGINEERING)

Low viscosity engine oils lower in sulfated ash, phosphorous and sulfur named as Low-SAPS oils have been evaluated regarding the influences on the friction and/or wear characteristics for the cam follower in valve train and the power loss of a working engine. The following study results were made obvious. (1) The power loss in the valve train with a roller follower supported with a needle bearing becomes larger than that in the one with a roller follower supported with a slide bearing. There, the ultra low sulfur oils (ULS) are lower in friction than DH-2 formulated oils, but the lubrication becomes severer under the high rotation speed. (2) Under the slide contact of a slipper follower, however, the ULS oil is higher in friction than the DH-2 oil, where the wear rate for the ULS oil is as high as that for the DH-2 oil when contaminated with soot. (3) The ULS oil made the piston ring scuffed under the high load and temperature conditions of engine operation