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).
Gearbox design improvements and addressing gears working out of mesh for various car models.
| Identifier | ExFiles\Box 94\1\ scan0357 | |
| Date | 3rd April 1936 | |
| Fr. c. Hs.{Lord Ernest Hives - Chair} RHO. Da.{Bernard Day - Chassis Design} E/HDY.{William Hardy}1/HP.3.4.36. Gearbox Gears working out of mesh. We recommend that the present diametrical clearance of from 6 to 7/1000" between the sliding pieces and the shafts which is allowed for eccentric movement of the gear and eccentricity of the teeth should be increased to 10 to 11/1000". We have frequently observed from markings on the shaft that the present clearance is insufficient. There is the question whether on the Phantom III the close fitting splines will prevent the sliding piece from moving the amount of this increased clearance. We also suggest that on the SpectreCodename for Phantom III box with lubricating schemes for gear bushes we should revert to the bushes pressed in the gears which we had originally, but abandoned owing to seizures. With regard to the box for Wraith, we were contemplating the use of a solid sliding piece for the 2nd speed with greater length in proportion to diameter than for the piece on the Phantom III which gave trouble. However now that we have had such a piece work out of mesh on a Phantom II we think that it would be wise to adhere to the present design which we have on the 2nd speed of the Phantom III which besides being much more perfect in action reduces the length of the box by 1" over what would be thought necessary with the solid piece. The Phantom III scheme should be still further improved by the use of only three splines clear on the top and bottom on the shaft, instead of six, with the object of preventing any distribution of load except a perfectly even one on the splines. With six splines it is possible that the load is being taken by two splines diametrically opposite which means a much reduced resistance to rocking. The reduction of area should be of no consequence with casehardened splines particularly on the 2nd speed gear which is seldom used. E/HDY.{William Hardy} | ||