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).
Evaluation of various bearing designs, including pinion journal and double row types, based on road test performance.
| Identifier | ExFiles\Box 49\2\ Scan043 | |
| Date | 16th November 1921 | |
| Oy2 - G 161121 Sheet #2. Our pinion journal bearings are all deep groove un-slotted, having 8 7/8" balls, turned bronze cage, race radius .446" = 52% of ball dia., race depth .1312" = 15% of ball dia. We have run this scheme 1000 miles with a 15/52 axle, in which the thrusts are higher than with the 16/52, and have had no trouble. We consider the 100 miles test represented a far more severe conditions of use than can be expected to fall on the bear-ing in service, and actually do not suppose that the average car would meet with such heavy and prolonged thrust on the journal bearing in ten thousand miles running. Evidently from our own and Mr. Hives' tests, the journal bearing will successfully carry the occasional heavy reverse thrusts in backing out of snow or mud-holes, which had hitherto proved the general cause of failure on the plain thrust. Double Row Bearing on Front End of Propeller Shaft: We have tried on the experimental car the scheme shown in XA-1342 enclosed, by which the thrust in both directions is taken on a double angular contact bearing (New Departure) on the front end of the propeller shaft. This was run 100 miles with a 15/52 axle on low gear over the same route and in the same way as the reverse thrust test described above and showed equally perfect condition at the end of the run. It has since run about 2000 miles under very severe conditions, running a considerable part of the time at full throttle, 15 m.p.h. with the brakes on, to test for loading, and including the climb of Mt. Washington, 5000 ft. in 8 miles, taking 38 minutes in second gear all the time and up a very rough road. The bear-ing is still in excellent condition. We think, however, that the New Departure bearing is possibly not the best for this work and that it might be better to use a Hess-Bright deep groove double row bearing of the same di-mensions. The New Departure has the outer race in three parts, two raceways, and a steel shell spun over them, and is so designed as to take thrust on only one row of balls. Also, it uses small diameter balls. The Hess-Bright double bearing uses larger balls and consists of a solid inner and outer race like the ordinary deep groove bearing, but having two grooves in each race, which are said to be so accurately spaced that thrust loads are taken equally by both races. It is virtually two deep groove bearings of standard design with a common outer and inner race. | ||