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).
Analysis and proposed improvements for a broken RR.F.10 rocker arm.
| Identifier | ExFiles\Box 43\3\ Scan090 | |
| Date | 4th December 1926 | |
| To RG{Mr Rowledge} & HS.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} c. to BJ. BY.{R.W. Bailey - Chief Engineer} X4003 RL/M4.12.26. RE BROKEN RR.F.10 ROCKER ARM. X.4003. We take it that the broken bar is on the inlet side, and assume that it broke in the centre first, also that it was not influenced by a broken rocker, or damaged by a broken rocker previously. We further assume that the material is a nickel steel drawn tube. To overcome this trouble I propose that we increase the external diameter on the inlet side only of the rocker bar to .625 using a decreased bore of .3, also that we should use a higher class of material of the same quality as used for the con. rods on the engine, and of the same brinell hardness. The oil holes should be moved into a vertical position, and there should be one only at the top opposite each bush in the inlet rocker. This new shaft is 58% stronger than the old one, and additionally we want to put the fatigue limit of the improved material up another 40%. We think the direction of the fracture is horizontal, and that it is due to the action and reaction of the cam creating a reversing stress in a lateral direction in the rocker bar, and not a vertical load which is in one direction only. A drawing is in preparation shewing this alteration. R.{Sir Henry Royce} | ||