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).
The ground clearance for jacking Goshawk cars with different tyre conditions.
| Identifier | ExFiles\Box 26\6\ Scan001 | |
| Date | 22th March 1922 | |
| Roy.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/TMW. X4080 Hs{Lord Ernest Hives - Chair}/TMW2/LG22.3.22. JACKS FOR GOSHAWK CARS. X4080 X3602 Referring to your Roy{Sir Henry Royce}/GEA2/AG10.3.22. The minimum clearance, that is with tyres deflated, is 7 1/2", this being taken at designed position for jack. Inflated, the measurement is 10 1/2". These figures are taken with a tyre pressure of 50 lbs. sq.in and 820 X 120 size of tyre. The figures for the rear axle cover the measurement for the front axle. It should be noted that with a 34" straight-sided tyre, the maximum lift to clear the ground will be at least 4" more than the figure quoted above. Hs{Lord Ernest Hives - Chair}/TMW. | ||