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).
Negative impact of larger diameter wheels on armoured car chassis and axles.
| Identifier | Morton\M21\ img059 | |
| Date | 8th October 1920 | |
| To BA. from R.{Sir Henry Royce} Copy to Cd. " " BN.{W.O. Bentley / Mr Barrington} " " HS.{Lord Ernest Hives - Chair} " " PN.{Mr Northey} " " R.R. of America Inc. (For the attention of OY.) Handwritten notes top right: Rep 6 8-10-20 R1/G30/R/20 R.{Sir Henry Royce} V.{VIENNA} ANTI LARGER WHEELS - HIGHER STRESSES AT HIGH SPEEDS. Stamp: ORIGINAL RECEIVED [date illegible] OCT 1920 X.4195 RE ARMOURED CARS. I am definitely against larger diameter of wheels for our chassis, because they increase the stresses in the axles, and cause greater translation sideways of the axle when the wheels rise over humps or drop into holes, and this causes stresses, especially at high speeds. If, however, tyres for the diameter of wheel we recommend cannot be obtained, to carry the load, we conclude that there is no alternative. We do not know the value of the increased road clearance, but unless this is of great importance we should think the risk of damage to the chassis would be greater than the advantage gained by the extra 2½" diameter of road wheel. In conclusion, I can only express my extreme regret to hear that the larger diameter of wheels is likely to be adopted. Perhaps it would be as well to refer to the armoured cars that were used during the war. Kindly let me know what size of tyres they were fitted with, and whether they were satisfactory or otherwise. R.{Sir Henry Royce} | ||