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).
Crankshaft bearing issue, steering wobble, improvements for rear shock dampers, and proposed back axle ratios based on vehicle weight.
| Identifier | Morton\M22\ img129 | |
| Date | 8th October 1920 | |
| Contd. -3- E1/G8.10.20. Mr. Royce thought the thud on 1.EX was unusual, with which Mr. Hives agreed on trying the car. It was finally concluded that a crankshaft bearing probably has become slack through wear or running out. This chassis has done several 10,000 miles, and been well thrashed out, but it is just possible that Castrol is not all we thought it to be. 1.EX is being returned to Derby for examination. STEERING - 40/50 CHASSIS. H.P. X.3791a. X.457. The combination of set-up springs, friction damping irreversible and central steering, is the one Mr. Royce considers important. Mr. Hives reports that this combination tends to suffer from low speed wobbles. Although leaning the pivots back encourages wobbles, the customers like it because of the self-steering characteristic of the car introduced thereby. Mr. Royce thinks there is no gyostatic actionnin wobbling as it takes place on a road having a perfectly smooth surface. REAR SHOCK DAMPER - 40/50 H.P? CHASSIS. X.3912b. X.3461b. The following five points must be incorporated to make the 40/50 H.P. rear shock damper a success:- for (1) Taper serration securing the lever. (2) Ferodo friction discs instead of fibre. (3) Ball bearing instead of plain bearing on outside. (4) Three times the number of castellations on the drum. (5) Filling with grease gun and having vent indicating when shock damper is full. BACK AXLE RATIOS - BUZZARD AND GENERAL. X.3832. X.3457. Referring to the back axle. Mr. Royce stated that he thought we ought to have a heavier and stronger axle of lower gear ratio for covered cars, and he fixed up the following table of weights and ratios, shewing how he thought the ratio should vary with the weight:- 2 tons - 3 to 1 ratio. (17x52 2.25 tons - 3.25 to 1 ratio. 2.5 tons - 3.5 to 1 ratio. 2.75 tons - 3.75 to 1 ratio. 3 tons - 4 to 1 ratio. 14 x 52 / (3.821) It will be noticed that the ratio does not vary in direct proportion to the weight, but the reason for this is that it would not be practicable and productive of the best all-round results, to fit a 4.5 to 1 axle to the three tonner, which would be in proportion to a 3 to 1 axle for the two tonner. Mr. Royce wishes to know what our competitors gear ratios (both change speed and back axle). Contd. (Upside down text at bottom: R.R. 235A (100 T) (S.H. 169. 11-8-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2890) | ||