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).
Distortion issues with Idler Gears for 25/30 & Bentley engines, recommending a softer SZNX material as a solution.
| Identifier | ExFiles\Box 136\1\ scan0192 | |
| Date | 10th December 1936 | |
| 1155 F.J.H. Where did the 45º angle gears we tried get to? Rm.{William Robotham - Chief Engineer} To R.{Sir Henry Royce} & Hs.{Lord Ernest Hives - Chair} From RHO. C. to By.{R.W. Bailey - Chief Engineer} C. to Rm.{William Robotham - Chief Engineer} C. to E/Jnr.{Charles L. Jenner} RHO.11/AJ.10.12.36. TIMING GEARS. 25/30 & BENTLEY. With reference to the above, from a brief survey the majority of the Timing Gear troubles are centred on the Idler Gear which is a very flexible piece and readily distorts when undergoing the various heat treatments. It is impossible to introduce grinding owing to the limited capacity of this process. Consequently, in view of the difficulties encountered it is recommended that the Idler Gears on both the 25/30 and Bentley engines should be produced in SZNX material and left in the soft condition. These pieces would be fitted with a Brinell of 360 to 380 and would remove the distortion troubles because gearcutting would be the final operation so that good tooth form should be obtained. It will be remembered that six sets of Fabroil Idler Gears were fitted on these engines sometime ago and were satisfactory. This being so, there is no reason why a soft gear in SZNX should not be even more satisfactory and would prove to be an immense economy since it is now realised that this particular gear is the cause of the Timing Gear troubles on these engine units. Unless we hear to the contrary we intend to put through half a dozen of this type of gear and get Rm.{William Robotham - Chief Engineer} to run them on Experimental engines with a view to introducing on Production at the earliest possible moment. Swell Have told R.H.C. that he can put one of these soft RHC.{R. H. Coverley - Production Engineer} gears on the unit for 6 BIV if he can get it-ready in-time Rm.{William Robotham - Chief Engineer} | ||