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).
Comparing the bearing sizes, load ratings, and performance of a Buick type pivot against other designs.
| Identifier | ExFiles\Box 125\3\ scan0152 | |
| Date | 6th November 1940 | |
| 1049 C O P Y. To Rm.{William Robotham - Chief Engineer} from Ev{Ivan Evernden - coachwork}/DB.{Donald Bastow - Suspensions} c. to Ev.{Ivan Evernden - coachwork} c. Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} Ev{Ivan Evernden - coachwork}/DB.{Donald Bastow - Suspensions}5/JH.6.11.40. With reference to Rm.{William Robotham - Chief Engineer}5/ML.29.10.40, the bearing sizes on the Buick type pivot were fixed to maintain the same stress in the pivot stub as with the previous hollow pivot stub. The Buick pivot drawn from the actual part and shown on EXS.1941 has an inner bearing whose rating is 1820 lbs. at 600 r.p.m. The outer bearing is smaller than the smallest shown in the New Departure catalogue; It therefore must have a rating less than 865 lbs. at 600 r.p.m. The bearing separation is approx. 3". Our Buick type pivot shown on PL.167 and PL.229 has an inner bearing whose rating is 2135 lbs. at 600 r.p.m. and an outer bearing with a rating of 1305 lbs. at 600 r.p.m. The bearing separation is 3.25". Under cornering conditions, therefore, assuming equal rolling radii, the inner bearing of our design will stand 27% more sideways load than the Buick. The outer bearing will stand over 63% more sideways load than the Buick under cornering conditions. Our stub-design of PD.240 fitted to 30.G.VII. was run with deep groove ball bearings. The inner bearing rating (Hoffman) is 1550 lbs. and the outer 1150 lbs., both at 600 r.p.m., and the bearing separation is 3.25". Hoffman ratings are based on a longer life than the New Departure but even allowing for this it appears that our Buick type pivot is at least as good in bearing equipment as the scheme we have been running and is certainly better than the Buick of the size for which I have particulars. In the circumstances I do not propose to alter the Buick type pivot already designed. Ev{Ivan Evernden - coachwork}/DB.{Donald Bastow - Suspensions} | ||