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).
Proposal for an experiment to reduce gear noise in the Spectre Gearbox by increasing shaft stiffness.
| Identifier | ExFiles\Box 94\1\ scan0111 | |
| Date | 9th April 1935 | |
| To Hs.{Lord Ernest Hives - Chair} & RHC.{R. H. Coverley - Production Engineer} Copy to Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} BY.{R.W. Bailey - Chief Engineer} Da.{Bernard Day - Chassis Design} +328 HDY.{William Hardy}2/MN.9.4.35. [Handwritten note] GRY{Shadwell Grylls} and Hdy{William Hardy} We should follow this up. Rm{William Robotham - Chief Engineer} SPECTRECodename for Phantom III GEARBOX. Stiffness of Shafts. We suggest that the following simple experiment is made to determine whether there would be any reduction of gear noise by the use of stiffer shaft. The idea is that by clamping the various gears, bearings and distance washers endwise with a force of 10,000 lbs.(which is sufficient to prevent the osses from separating under the bending moment applied by the gears,) the effective outside diameter of the shaft becomes that of the outside of the gear osses, etc., and this results in an increase of bending stiffness of 200%. As regards the use of this method permanently, our experience has been that such endwise clamping as we have occasionally used has not been sufficient to prevent movement of the ball-bearing inner races. This experience is confirmed by the Cadillac gearbox on which the 1st.motion shaft bearing, although clamped, shows unmistakeable signs of rotation and would eventually have become free endwise no doubt. However, it appears to be not out of the question to apply enough end load to prevent movement and as there is benefit from clamping in reducing chunking in the drive we think that further consideration may be worth while if the result of this experiment is favourable. With regard to the experimental testing we propose that the nuts at the rear end of the 3rd. motion shaft and the front end of the layshaft should be made to clamp the pieces on these shafts by substituting for the plain washers behind these nuts, washers broached so as to pass on to the splined shaft by the few thousandths which the pieces will deflect. From figures given in Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}13/KW.8.4.35 an end load of 4.75 tons (10,250 lbs) is given by a 7/8" 20 T.P.I. nut when tightened with 120 lbs.ft.torque. Increasing this in proportion as the nut diameter and ignoring the difference of thread angle, if any, we get 120 x 1.062 / .625 = 205 lbs.ft. Say 200 lbs.ft.to give 10,000 lbs.end load. | ||