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).
Estimated rockershaft torque on various chassis following a twisted rocker shaft incident.
| Identifier | ExFiles\Box 95\1\ scan0468 | |
| Date | 4th January 1938 | |
| To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} c. Da.{Bernard Day - Chassis Design} 350 Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer}5/MH.{M. Huckerby}4.1.38. STEERING ROCKER SHAFTS. Owing to the recent case of a twisted rocker shaft on a Ph.III steering we asked W. Bell to measure the torque required to cause this twist. We attach his report on the tests. In normal service the maximum load on the steering gear occurs when turning the steering wheel with the car stationary, and is 37 lbs. ft. at the wheel. With an angular velocity ratio of 15.3 and mechanical efficiency of 80% this is equivalent to 37 x 0.80 x 15.3 = 452 lbs. ft. at the rocker shaft. The safety factor is therefore 1000 / 452 = 2.2 . We give below the estimated rockershaft torque on all chassis. All have the same dia. shaft and splines. Existing Standard Ph.III 452 lbs.ft. E Series Ph.III. Wraith Wheel Movement. 520 lbs.ft. Wraith 290 lbs.ft. M Series Bentley 320 lbs.ft. Continental Ph.III 39-EX 400 lbs.ft. We think that the increased load on E Series Ph.III will be catered for by the recent change of material from S/ZN to S/ZNX. Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} | ||