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).
Testing specially cut worm gears to reduce noise from the four-wheel brake servo system.
| Identifier | Morton\M20.3\ img028 | |
| Date | 19th June 1924 | |
| R.R. 496A (20H) (D.A. 652 20-8-24) J.H.D. EXPERIMENTAL REPORT Expl. No. 9940 9910 ORIGINAL REF HsS/LM19.6.24. To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. RH.{R. Hollingworth} c. to DA.{Bernard Day - Chassis Design} F.{Mr Friese} c. to EY. WOR.{Arthur Wormald - General Works Manager} SECRET - FOUR WHEEL BRAKES. NOISE FROM SERVO GEARS, GREATER THAN NORMAL (DRIVING) GEARS. We have recently tested a set of worm gears which were cut with a specially made hob. On the road these gears were equally as noisy as the previous gears, in fact, if anything they were worse for noise. We find, however, that the degree of noise does vary on different gears when similarly made. We do not think there is the least chance of getting Sales to accept cars until we get rid of the gear noise. Standard Gearboxes are condemned for muchless noise. On some of the cars also the noise is bad - it can be heard without any load at all on the brake pedal. The noise we get is a definite period - we should say that it is a torsional vibration in the servo drive. It comes on and off at definite speeds. It definitely does not originate from the engine because it can be obtained with the engine stopped and the car coasting. We have removed the back axle and universal joint and have still been able to get the same noise with the car in the shop. There is a possibility, seeing that the engine is then driving, that the vibrations might come from the engine under that condition. We suggest that we alter the ratio of the worm and also alter the ratio of the spur gears so that although we have the same ultimate reduction, if it is ... | ||