Costs and benefits of a separate starter gear ring for the Wraith Flywheel.
| Identifier | ExFiles\Box 8\1\ 01-page29 | |
| Date | 15th December 1936 | |
| X-1044 6 12 To Hm. {Capt. W. Hallam - Head Repairs} from Rm {William Robotham - Chief Engineer} /Smth. c. to S. c. to W. c. to RHC. {R. H. Coverley - Production Engineer} c. to Mx. {John H Maddocks - Chief Proving Officer} Rm {William Robotham - Chief Engineer} /Smth.7/JH.15.12.36. Wraith Flywheel - N.Sch.4882. We have been making further enquiries into the need or otherwise for a separate starter gear ring on Wraith, and see no reason to depart from the conclusions given in Hs {Lord Ernest Hives - Chair} /Smth.17/JH.3.9.36., in which we recommend that we should adhere to the present design. We are informed by the Repair Dept., that during the last 12 months they changed 10 20/25 flywheels under guarantee owing to gear wear, and no Bentley ones. The estimated saving in Repair Dept. labour if a separate gear ring was provided is £6.0.0. per car, owing to the fact that in this case the crank would not have to be removed for rebalance. The evidence at present indicates that flywheel teeth are becoming less susceptible to damage due to improvements in starter motors, but assuming that this is not so, we cannot expect a greater annual saving in Rept. Dept. labour costs than £63. due to adopting a separate starter ring. The material and labour costs of the Wraith flywheel would be £3.2.9d. as designed with a separate starter ring, compared to £1.3.10. if made integral from a S/HC forging as is done at present. The separate gear ring alone costs £1.13.7d, i.e. about 10/- more than the whole flywheel with the existing design. Thus, if N.Sch.4882 is adopted we shall be increasing the factory costs by about £1500 p.a. to save £58 in the Repair Dept. The greatest source of saving in the present design is in the material cost, Willenite costing about 5½d {John DeLooze - Company Secretary} /lb. compared to about 3d/lb. for a S/HC forging, but even if we made both the flywheel and starter ring of S/HC forgings, we should still loose in the long run. In view of this we consider that N.Sch.4882 | ||
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).