242 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1947 



The smaller wheels previously mentioned, the higher speeds result- 

 ing from greater engine power, and the general adoption of internal 

 expanding four-wheel brakes raised another problem for the petroleum 

 industry in lubricating the wheel bearings. The wheels were turning 

 faster, creating higher operating temperatures in the bearing and 

 greater centrifugal force which tended to throw the grease out of the 

 bearings through the oil-retaining ring into the braking system to 

 cause malfunctioning of the brakes. Grease compounding quickly re- 

 ceived a complete overhauling in order to furnish a wheel-bearing 

 lubricant which would maintain its consistency at high temperatures 

 of operation, neither separating into oil and soap with resultant loss of 

 oil and clogging of the bearing with soap, nor changing in physical 

 characteristics as the temperature increased to a point where the grease 

 would leave the bearing as the result of excessive softness. 



General chassis lubricants also had to be restudied. All the pre- 

 viously mentioned developments were making cars run with less noise. 

 Changes in spring-hanger design had increased the bearing loads on 

 spring shackles so that there was an increased tendency for the shackles 

 to squeak and with less noise competition the squeaks were more 

 noticeable. New chassis lubricants were developed which could be 

 pumped readily by the automatic chassis-lubricating equipment being 

 installed in the service stations and would stay between the bearing 

 surfaces in spite of heavy impact loading and the tendency for 

 splashed water from the highway to wash this grease away. This 

 particular development, incidentally, is probably one of the most 

 ingenious feats of compounding that the industry has accomplished 

 and is probably the least known generally. 



CHANGING PETROLEUM REQUIREMENTS OTHER THAN AUTOMOTIVE 



During this period under discussion the automobile, although acting 

 as a pacesetter, was not the only requirement which was causing rapid 

 changes in petroleum technology. The aviation industry, which 

 had even more to gain from power from smaller engines, was stepping 

 out ahead in requirements for high octane, high chemical stability fuel. 

 The aviation-engine designer increased compression ratio with the 

 attendant advantages previously discussed, reached the mechanical 

 limitation to high compression posed by necessity for valve and spark 

 plug clearances and engine roughness, and then moved on to even 

 higher levels in antiknock requirements by adopting the principle of 

 supercharging. 



The supercharging approach to this problem is interesting and 

 deserves further examination. If compression ratio cannot be in- 

 creased readily, another way to get the same effect from a given engine 

 is to pack more air and fuel into the cylinders by forcing it in under 



