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).
Gear tooth proportions for gearbox gears, including corrected and uncorrected types.
| Identifier | ExFiles\Box 136\2\ scan0265 | |
| Date | 25th April 1940 | |
| To Rm{William Robotham - Chief Engineer}/HH. from Ev{Ivan Evernden - coachwork}/Tln. c. to Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} c. to Ev{Ivan Evernden - coachwork}/JD.{J. Draper - Frames} c. to Ev{Ivan Evernden - coachwork}/EJB. c. to Ev.{Ivan Evernden - coachwork} 1153 Ev{Ivan Evernden - coachwork}/Tln.3/JH.25.4.40. Gear Tooth Proportions - Gearbox Gears. ZJH We have confirmed from Cgh{W Clough}/CRL.{C. R. Lisson} and Ev{Ivan Evernden - coachwork}/Burkinshaw that the following gear proportions were agreed upon some time ago by Gry.{Shadwell Grylls}, McWilliams (Works) and CRL.{C. R. Lisson} Uncorrected Gears. (1) All gear blanks have a normal addendum = 1.000/DP Therefore where teeth are not ground the finished gear has an addendum of 1.000/DP. (2) Ground Gears. After cutting the teeth and before grinding the teeth the gear is ground circular on its outside dia. The stock removed = .100/DP radially. Therefore finished ground gears have an addendum = .900/DP. (This means that gears are cut with the same addendum whether they are to be ground or not) (Gry.{Shadwell Grylls} has demonstrated that the reduced addendum tends to quieter operation) (3) Normal Dedendum = 1.250/DP or 1.157/DP depending on method of gear cutting. Ground gears should always have 1.250/DP to give grinding clearance. Corrected Gear. (Ground or Unground) (4) The whole depth of tooth is generally 2.250/DP (which is greater than for uncorrected ground gears) but this may be varied for certain forms of correction (e.g. where the wheel and pinion corrections are not equal and opposite) P.T.O. | ||