From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Analysis of temperature test results for oil and water under different vehicle operating conditions.
| Identifier | ExFiles\Box 107\2\ scan0134 | |
| Date | 25th May 1938 | |
| -2- Tests III and IV and VII and VIII indicates that it is not advisable to dispense with the oil cooler on cars fitted with all W/M bearings and no overdrive unless further test bed tests are made to determine the precise effect of continuous oil temperatures of 120 - 125°C on W/M bearing life. The cruising tests (VII and VIII) carried out in this connection were made in order to approximate to the conditions under which a car is likely to be run by a reasonable driver or one adhering to the recommendations made by R.R. Ltd. as regards maximum advisable continuous speeds on Continental motor roads. Finally, tests V and VI indicate clearly the effect of water temperature on oil temperature - it will be seen that comparing test V with test III and test VI with test IV a rise in water temperature of approx. 20°C gives a rise in oil temperature of 16°C in overdrive, while in direct gear a rise of water temperature of approx. 16°C gives a rise in oil temperature of 12°C. In each case the oil temperature rise is 75% of the water temperature rise. From these figures it is seen that under the conditions of tests V and VI the heat to the oil is dissipated roughly in proportion of 55% to cooling water and 45% as loss to atmosphere direct from engine whereas under conditions of tests III and IV the proportions are roughly equal (50% each). The tests I, II, III and IV were carried out at 100°C water temperature approx. as representing the limiting conditions likely to be met under continuous operating conditions in hot weather (actually the maximum possible is 106°C - regulated by the radiator steam valve), while tests VII and VIII were carried out at approx. 90 - 93°C water outlet temperature as representing temperature likely to obtain under fast cruising conditions in hot weather. Assuming 35°C or 95°F as being highest atmospheric temperature under which continuous operation is likely we have calculated that the oil temperatures will rise approx. 4°C above those given on attached sheet( which without the oil cooler means ultimate temperatures of 130°C and 142°C on overdrive and direct gears respectively and an 80 m.p.h. cruising temperature of 125°C on direct gear). Tests V and VI indicate critical air temps. of 25.5°C and 30.5°C (uncorrected) which are about 8-10°C down on the standard Ph.III figures. | ||