Engine Temperature as Affecting Lubrication and Ring-Sticking 370143
IN the investigation of combustion in Diesel engines considerable emphasis was placed upon temperatures prevailing in metal parts adjacent to the combustion-chamber envelope. In mobile-type Diesel engines these temperatures are influenced directly by design characteristics, service conditions, atmospheric temperatures, and operating schedules. Of particular importance is the combined effect of the factors upon piston temperatures and, therefore, of direct consequence to lubrication.
Oxidation tests of lubricating oils for metals have demonstrated that gummy and carbonaceous products are deposited in relation to the heat gradient in the piston, particularly in the ring-belt region. The type and extent of these deposits are influenced further by the source of the crude and by the method of treatment and of finishing the lubricating-oil stock.
The gummy deposits from the lubricating oil act as binders to congeal carbon and dust in the ring-grooves to produce ring-sticking. Even though mechanical construction and thermal regulation can provide some alleviation for ring-sticking, the great variety of service, operating, and atmospheric-temperature conditions encountered in Diesel tractors operating throughout the world calls for specialized lubricants.
This paper deals with the program of investigation of the influence of engine temperature on lubrication and ring-sticking and the development of improved lubricants for high-duty Diesel service.