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).
Bearing tests comparing Allison Engineering Company bearings with those produced at the Derby factory, including recommendations.
| Identifier | ExFiles\Box 173\1\ img400 | |
| Date | 2nd February 1934 | |
| To HS{Lord Ernest Hives - Chair} from RHC{R. H. Coverley - Production Engineer} U.C.A. SG{Arthur F. Sidgreaves - MD} NORRGEBY/HS{Lord Ernest Hives - Chair}/RHC{R. H. Coverley - Production Engineer} Indianapolis, Indiana February 2, 1934 I enclose report on bearing tests carried out at Stutz Factory, Indianapolis, copy of which has been handed to the Allison Engineering Company. It will be observed from figures of test that behaviour of Allison Bearings was much better at various speeds than Bearings produced at Derby, the general condition of bearings at completion of the test being excellent in comparison. Whilst temperature of centre bearing reached 132 C. there were only slight signs of lead sweat and this apparently occurred during test at 3250 R.P.M. when temperature rose to figure stated and torque increased slightly. At this temperature lead would sweat freely from Derby produced bearings. Allisons recommend different composition for Main Bearings, to that used for connecting rods, particulars of which will be obtained later; and in spite of fact that grooved type bearings stood up to test satisfactorily, recommend grooveless bearings having additional oil holes as previously reported and state that not only does this permit of reduced bearing clearances but also ensures improved lubrication under all conditions as oil, being fed to bearing through series of holes, distributes lubrication across bearing and additional holes prevent break down of oil film. Whilst this test proved bearings to be satisfactory with unbalanced crank, semi-balanced crank shaft is recommended. Tests with unbalanced crank will prove bearing reliability. Judging by conditions of Allison bearing at completion of test, the fact of increasing Bearing Flanges by .125 is to be recommended as it certainly prevents closing in of bearing for which stress releasing treatment has been introduced at the works. The slight increase in weight is worth while if fault referred to can be definitely eliminated by this modification. The importance of Brinell hardness of crankshafts is stressed by Allison as considerable bearing improvement has been obtained by increasing Brinell of cranks to 340-363. Believe our standard to be 286-321, while increase in Brinell figures would not seriously affect machining operation. Only straight mineral oils are recommended. Oils which contain lard or Castor Oil should not be used. The stiff back design of R.R. Main Bearings is considered entirely satisfactory and should be adhered to. | ||