Graph showing the results of a 20 HP crankshaft torsion test, tracking changes from forging to the finished shaft.
| Identifier | ExFiles\Box 31\2\ Scan076 | |
| Date | 6th December 1927 | |
| FORGING DIMENSIONS (AVERAGE) A 2.375" JOURNALS B 1.900" CRANKPINS C 1.100" WEB (THICK) D 1.350" TO INSIDE FLASH E 1.200" OUTSIDE FLASH F 2.550" WEB WIDTH G 4.625" CRANK 2.250" CRANK RADIUS 20 H.P. CRANKSHAFT. — TORSION TEST. — FORGING TO FINISHED SHAFT. GRAPH I ① AS FORGED ② JOURNALS TURNED FROM 2.375 DIA. TO 2.200 DIA. WEBS 1.015 THICK. ③ CRANKPINS FROM 1.900 TO 1.625 DIA. WEBS .805 THICK. ④ JOURNALS REDUCED FROM 2.200 TO 2.030 DIA. ⑤ JOURNALS BORED 1.250 DIA. ⑥ WEBS PROFILED FROM 2.550 WIDE (FORGED) TO 2.200 WIDE. ⑦ CRANKPINS REDUCED FROM 1.625 TO 1.530 DIA. ⑧ CRANKPINS BORED .750 DIA. (FINISHED) PERCENTAGE REDUCTION IN STIFFNESS PER OP. 32.5% 35% 7% 10.5% 18% 6% 6% Y-AXIS: TORQUE ON NOSE — LBS FT X-AXIS: ANGULAR DEFECTION — DEGREES | ||
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).