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).
Failure of side wheel carriers with diamond mounting and suggesting design improvements.
| Identifier | ExFiles\Box 179\1\ img019 | |
| Date | 14th October 1931 | |
| HS{Lord Ernest Hives - Chair}/RM.{William Robotham - Chief Engineer} FROM DA{Bernard Day - Chassis Design}/EV.{Ivan Evernden - coachwork} C. to SG.{Arthur F. Sidgreaves - MD} BY SIDE WHEEL CARRIERS WITH DIAMOND MOUNTING. DA{Bernard Day - Chassis Design}/EV{Ivan Evernden - coachwork}3/M14.10.31. x7600 x5600. We thank you for your HS{Lord Ernest Hives - Chair}/RM{William Robotham - Chief Engineer}2/AD21031., and the broken stays between the carrier and the dashboard. We note that these failed on the bumping rig after 3 1/2 and 8 hrs. respectively, the latter being on a jellying period. This issue is not one of steadying the spare wheel primarily. We think that the stays such as you have tried on N. sch. 3322. rigidly attaching the wheel carrier to the dashboard are attempting to hold the side channel of the chassis frame from twisting. It will be seen that the front springs have considerable leverage and can put a lot of torsion on each individual side channel. We therefore feel that had the stay not have broken possibly a lump would have come out of the dashboard. We suggest that you try feet to the wheel carrier tubes on the chassis frame which have two horizontal bolts and little heel in the vertical direction so that the chassis frame is not held torsionally by the triangulation of the wheel carrier. At the same time we think that the pieces on the dashboard and the tie should be increased in strength. As previously stated we do not think this staying system can be looked upon as anything but a temporary expedient. We sent you some stays - N. sch. 3300. - for the 20/25., and N. sch. 3303. for P. 2. The former you made and found not to produce the stiffness required. We asked you then to make some experiments outlined in DA{Bernard Day - Chassis Design}/EV{Ivan Evernden - coachwork}1/8931. This would easily go on N. sch. 3303. for P. 2., and would also go on 18-G-4., and has a dashboard wider than standard which would permit of the angle. We are very anxious that you should make these tests without delay as the whole of a section of J.{Mr Johnson W.M.} 3. is held up pending your report. DA{Bernard Day - Chassis Design}/EV.{Ivan Evernden - coachwork} [Handwritten] Revised Stay, N.Sch. 3356 herewith for 20/25HP | ||