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).
Examination of issues with AC.2 bearings on Bentley chassis.
| Identifier | ExFiles\Box 114\3\ scan0045 | |
| Date | 30th November 1938 | |
| W/S. (C). BY.6/G.30.11.38. RE: BENTLEY CHASSIS WITH AC.2 BEARINGS. In reply to C.13/G.29.11.38. and further to BY.20/N.28.11.38. I am now in the position of having been able to examine the five sets of bearings which were taken out of the following chassis :- B.96.LS. B.70.LS. B.169.KU. B.177.KU. B.159.KU. In every case the bearing clearances appeared to be normal, and on the face of it the bearings were in good condition. By this I mean I should not have expected anybody either in our Works or at K.{Mr Kilner} to have commented adversely on the appearance of the bearings. There are, however, present, certain indications which to a person well acquainted technically with aluminium bearings point clearly to the fact that 'ageing' is taking place, and that as I was afraid in the first instance this ageing is the cause of the trouble. In an ordinary way the heat treatment which we give to our aluminium bearings representing an artificial ageing, completely stabilises the material, but in the case of the AC.2 bearings the treatment given was not sufficiently drastic to completely eliminate ageing with the subsequent growth which occurs as ageing develops. Four out of the five sets of bearings examined from the chassis quoted above give clear indications that the bearings are on the tight side; the 5th set, however, which apparently were fitted with more clearance initially and in which evidently the nip was on the small side, evidenced by the slight movements which have taken place on the backs of the bearings, had sufficient initial clearance to allow the ageing effects to take place without depleting the running clearance to a dangerous point. Coming now to the general position, the facts are as follow :- (1). Out of the 75 cars fitted with AC.2 bearings we have 10 serious complaints, which represent 13% failures. | ||