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).
The development and testing of steering roller followers, comparing different manufacturers and designs.
| Identifier | ExFiles\Box 153\1\ scan0276 | |
| Date | 20th April 1939 | |
| 1300. To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} c. Hs.{Lord Ernest Hives - Chair} c. Da.{Bernard Day - Chassis Design} c. RHC.{R. H. Coverley - Production Engineer} c. MX.{John H Maddocks - Chief Proving Officer} Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer}11/MH.{M. Huckerby}20.4.39. STEERING ROLLER FOLLOWERS. Some time after we first adopted the Marles type steering on Ph.III and 25/30 we experienced a number of failures of the bearings inside the roller follower. While the ball type roller of the 25/30 was being made by the Adamant Co. this was the most troublesome one. We therefore had this type made by Ransome & Marles in order to obtain more accurate grinding of the ball tracks. All the failures which occurred were of the fatigue type so we commenced rig tests which enabled the roller to be run at 450 r.p.m. under an exact reproduction of the manner of loading in normal service. The tests confirmed road results, namely, that while the Adamant made 25/30 ball type were inferior to the Ph.III type, the Ransome & Marles' ones were appreciably superior. At this time we needed a roller with the maximum possible load capacity for use on Ph.III with Wraith wheel movement suspension. In conjunction with Messrs. Ransome & Marles we developed the roller F.89447 in which the outer profile was the same as 25/30 but the balls were 0.3125 dia. instead of 0.250. On rig test this roller had twice the load capacity of the 25/30 type, and the ultimate failure indicated that the design was well balanced as all parts of the assembly failed together. A roller of this design completed 17,000 miles in France and is still running in MX.{John H Maddocks - Chief Proving Officer} at 50,000 miles. The design of the Wraith and 'M' Series Bentley roller was based on the above Ph.III roller. The outer roller was made of the same section as the new Ph.III roller, while the balls were reduced slightly from 0.3125 to 0.297 (19/64ths) in diameter and from 12 to 11 in number. This had to be done as the roller was of smaller diameter than Ph.III. | ||