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).
Specification table detailing the particulars of four different inner spring designs.
| Identifier | ExFiles\Box 95\3\ scan0025 | |
| Date | 7th September 1934 guessed | |
| SHEET (2). PARTICULARS OF INNER SPRINGS. | G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 81517 | G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 82237 | G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 82225 | G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 82236 Spring Designation. | A.1. | B.1. | C.1. | D.1. Wire Dia. | 0.464" | 0.462" | 0.487" | 0.495" Mean dia. of coils. | 3.00" | 3.012" | 2.987" | 2.980" No. of coils(effective) | 9 | 9 | 9 | 9 Normal load. | 950 lbs. | 971 lbs. | 1163 lbs. | 1243 lbs. Deflection to normal position. | 3.325" | 3.485" | 3.310" | 3.295" Free length. | 10.000" | 10.160" | 9.985" | 9.970 Max. load. | 1372 lbs. | 1381 lbs. | 1682 lbs. | 1800 lbs. Max. stress (Uncorrected) | 105,000 lbs/in² | 107,500 lbs/in² | 110,400 lbs/in² | 112,700 lbs/in² Max. deflection. | 4.800" | 4.96" | 4.785" | 4.77" Rate per inch | 286 lbs. | 278 lbs. | 352 lbs. | 378 lbs. Rate per inch at wheel | 39.2 lbs. | 38.2 lbs. | 48.3 lbs. | 52 lbs. Normally part of combination. | 1000 lbs/wheel. | 1100 lbs/wheel. | 1200 lbs/wheel. | 1250 lbs/wheel. | ||