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).
Design suggestions and issues related to a Bentley 11 rear axle pinion bearing.
| Identifier | ExFiles\Box 84\4\ scan0336 | |
| Date | 5th November 1937 | |
| 202 Da.{Bernard Day - Chassis Design} C. EX. C. RM.{William Robotham - Chief Engineer} GERY DA{Bernard Day - Chassis Design}/Hdy.{William Hardy}15/G.5.11.37 BENTLEY 11. REAR AXLE PINION BEARING. We send herewith PD.40 showing our suggestion for a more rigid mounting of the pinion. We think that there is no doubt that this scheme will give the necessary durability and control against excessive deflection, but we are not yet certain that it will remedy the axle noise on the over-run. We have asked for a test to be made on the standard bearing with the journal race reduced by .002" so that there will then be as much radial clearance as the roller bearing of the three row bearing is ever likely to have. The bearing is to be preloaded to the amount found necessary to prevent the noise on a standard bearing. This would appear to give the same condition as regards radial control as will exist with the three row bearing. Although there will be .001 radial freedom from the centre, the load due to preloading will cause friction on two surfaces which will have considerable damping effect we imagine. The three row bearing shewn is to Messrs. Hoffmann's drawing No. 41-477, Section 74, excepting that we have increased the bore to 1.312 from 30 m/m, and that gaps are provided between the outer races. Also the oil way slots are deleted. Made as we suggest, the widths of the outer races are not important, nor is the spacing of the ball raceways in the inner race. Offsetting the above reduction in cost is the increased size of the bearing compared with the original to drawing number 41-477, Section 2 (print attached). There is also a slightly more expensive cage with the later bearing. We attach Messrs. Hoffmanns estimate of the 4th August for bearings to drawing 41-477, Section 2. Referring to the above mentioned gaps between the outer races, we understand that when the races are made exactly the width to give the required preloading and the bearing is closed together by a nut which has no stop other than the bearing itself, distortion of the bearing races occurs which has been known to tighten up the inner races excessively. We understand that to remedy this the construction shown by G.CD.58 was adopted with a lip on the nut. We are now suggesting that as the nut must have a stop independently of the bearing, the bearing races should be given clearance. This will cheapen the bearing and will prevent any possibility of more endwise load being put on the bearing by the nut than | ||