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).
Improvements to gearbox silence through changes in gear design, grinding processes, and bearings.
| Identifier | ExFiles\Box 178\3\ img002 | |
| Date | 1st January 1932 | |
| FROM R.{Sir Henry Royce} DA{Bernard Day - Chassis Design}/HEV) (AT Le CanadelHenry Royce's French residence.) HS.{Lord Ernest Hives - Chair} ) Copy to CC. WOH. Hives ORIGINAL SILENT GEARBOXES. Very many years ago we introduced single helical side-shafts and got much greater silence when idling, and on 3rd. and other gears. I think if we now go straight for the most perfect way of getting the tooth form and spiral angle right, all will again be well and we shall have a passably silent 3rd., but we must not expect anything less than correct grinding to give us results up to RR. standard. Unfortunately my influenza and bronchitis has kept me in or I could say more exactly what 20-G-4. (a bad box) has done by some running in, but idling seems to have gone only slightly better, and under load very definitely better than 2nd. This 2nd. Dodd thinks is a decidedly poor gear. You will remember that I worried for days to get sound construction that could be ground after hardening, yet we were not grinding with proper tackle up to the end of the year. Tight ball bearings are often noisy, roller being generally more silent. Plain bearings rarely shew up to be reliable with us for not seizing, though they are generally quieter than balls or rollers. I feel sure we shall waste less time and money by getting the proper thing at once, and cannot believe it will make any great difference by changing the pitch or spiral angle from the reasonable gears we have given you, which compare well with our good sideshaft practice. If however the gears were for one rate of revolution (like a ship's turbine gears) a change in pitch might make a great difference (because of synchronous vibration.) R.{Sir Henry Royce} RECEIVED | ||