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).
Table showing the number of turns required to raise a Universal Jack for each inch of vertical increase.
| Identifier | ExFiles\Box 139\2\ scan0145 | |
| Date | 9th November 1934 | |
| -2- Hs{Lord Ernest Hives - Chair}/Bwg.{J. C. Bowring}16/KW.9.11.34. The figures below show how the number of turns necessary to raise the Universal Jack through 1" increase as the "scissor" arms become more Vertical - 2½ turns to raise Jack 1" 3 " " " " 2" 3½ " " " " 3" 4½ " " " " 4" 6 " " " " 5" 8½ " " " " 6" 11 " " " " 7" 14 " " " " 8" Hs{Lord Ernest Hives - Chair}/Bwg.{J. C. Bowring} | ||