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).
Quarterly complaints report investigating rear axle pinion thrust bearing failures.
| Identifier | ExFiles\Box 47\3\ Scan002 | |
| Date | 16th January 1931 | |
| To Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer} & GWH.{George W. Hancock - Head Chateauroux} } from RHC.{R. H. Coverley - Production Engineer} c. WCr & Hy.{Tom Haldenby - Plant Engineer} X4117 RHCL/BE16.1.31. QUARTERLY COMPLAINTS. REAR AXLE THRUSTS We have been investigating rear axle pinion thrust bearing failures, which chiefly apply to 20HP chassis. Since we commenced our investigation By.{R.W. Bailey - Chief Engineer}, has looked over these bearings and instructed an alteration which consists of reducing the outside diameter, making bearing more self-aligning and so far, has given better results than previously. Whilst there may be some improvement, we doubt whether this alteration will solve the troubles, owing to the peculiar design of bearing. The bearing used is a double thrust and journal type(or New Departure type) and the outer races are retained by a mild steel shell, which is burnished over. The design is such that no guarantee can be given in the assembled condition, that the outer races are parallel and load is taken uniformly on thrust races. Judging by examination of the various bearings which have failed, it would appear that, in the assembly stages when shell was fitted, thrust races have become out of parallel, resulting in the load being localised when applied, and causing failures of the hardened surfaces on races and balls through chipping. Variation in the end clearance of bearings when delivered has been noticeable, and it is an important point resulting in some bearings having more end clearance than they should have, which allows pinion to float causing axle to be noisy. In other cases, end clearance is too limited which is liable to produce failures, and these points cannot be safeguarded in the assembly with a guarantee that all bearings have the same amount of clearance It is extremely difficult to discover such faults referred to, during inspection. It may be that shell of bearing is not of equal tightness round the whole of it's circumference, consequently when load is applied, shell stretches and either produces more end clearance or unequal clearance. -continued- | ||