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 Woodhead and Firths rear road springs under a 1700 lbs load.
| Identifier | ExFiles\Box 52\2\ Scan188 | |
| Date | 25th October 1928 | |
| COMPARISON OF WOODHEADS AND FIRTHS ROAD SPRINGS (REAR) 1700 LBS LEFT SIDE: WOODHEAD 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 DATA: 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 RIGHT SIDE: 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 DATA: 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 | ||