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).
The testing and performance of various alternative engine bearings, detailing failures and endurance results.
Identifier | ExFiles\Box 115\1\ scan0194 | |
Date | 15th December 1936 | |
-6- Alternate to the standard A.C.7. two tests have been run with Hoyt's Whitemetal on steel backed shells. The first of these, Eleven R.{Sir Henry Royce}, apart from the normal W/M.{Mr Moon / Mr Moore} analysis has a small amount of Cadmium, and failed mainly through bad adhesion as shown in Photo.No.7., after 11 hours running under full throttle endurance speeds. Other than the bad adhesion feature the bearings show minute fatigue cracks. The second E.J. is also similar to W/M.{Mr Moon / Mr Moore} with the exception that it contains a small amount of Silver, this material being used by Bristols in their aero engines. Considering that the inlet oil temperature to the bearings was kept constantly at 100°C, the results after 22 hours as shown in the Photo.No.8., are very promising. This run was brought to a compulsory finish by a crankshaft failure, but the inspection shows that butfor the centre main bearing, the running could have been continued much longer. The centre bearing has shed a small chunk and one of the intermediates cracking slightly, but otherwise the remainder are good. As soon as possible a run is to be taken with our own standard W/M.{Mr Moon / Mr Moore} bearings as fitted on the 25/30 so that we shall have a figure of merit against the Hoyts E.J. Initial runs have been taken with A.C.1. main bearings and the last examination after about 10 hours running shewed that no slack had developed. This particular engine is still being run for further information about slack and wear. RR.56. was first tested in the rear main bearings and after having to increase the end float from .002 - .003 to .003 - .004 this bearing ran under f load conditions for 15 hours without any hammering. When a complete set were fitted the centre main bearing seized almost as soon as the engine was run up to high speeds Upon dismantling, the centre crank-case bearing housing was found cracked so that until repeated, little comment can be made. We have, however, not very much faith in RR.56. for main bearings as due to its extreme hardness and structure, is not the kind of material to adapt as a bearing where the loads are more continuous especially in the centre where it has to accommodate for crankshaft bow. continued | ||