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).
Comparison of Woodheads and Firths 1700 lbs rear road springs, detailing load, camber, and bedding characteristics.
| Identifier | WestWitteringFiles\S\September1928-October1928\ Scan112 | |
| Date | 25th August 1928 | |
| COMPARISON OF WOODHEADS AND FIRTHS ROAD SPRINGS (REAR) 1700 LBS WOODHEADS 1700 THESE DIMS. SHEW AMOUNT OF 'NIP' NOTE VERY HEAVY BEDDING OCCURS ON EACH LEAF AT A PLACE COINCIDING WITH THE TIPS OF THE ADJACENT LEAF. AS SHEWN. TABLE: Nº OF LEAF | LOAD (FLAT CAMBER) | FREE CAMBER 1 | 1337 | .400 2 | 807 | .770 3 | 505 | 1.148 4 | 297 | 1.497 5 | 342 | 1.800 6 | 232 | 1.880 7 | 160 | 1.730 MAIN LEAF | 180 | 1.075 AVERAGE BRINELL - 402 FIRTHS 1700 THESE DIMS. SHEW AMOUNT OF 'NIP' NOTE THE LEAVES OF THIS SPRING BED HEAVILY AT THE ENDS AND EDGES. AS SHEWN BY SHADED MARKS. TABLE: Nº OF LEAF | LOAD (FLAT CAMBER) | FREE CAMBER 1 | 1244 | .325 2 | 679 | .605 3 | 527 | .862 4 | 387 | 1.175 5 | 287 | 1.370 6 | 260 | 1.610 7 | 175 | 1.732 8 | 142 | 1.680 MAIN LEAF | 135 | 1.010 AVERAGE BRINELL - 374 | ||