The failure of obsolete bottom tappets on a Wraith unit and proposed design modifications.
| Identifier | ExFiles\Box 158\4\ scan0254 | |
| Date | 3rd August 1938 | |
| 1360. To By. {R.W. Bailey - Chief Engineer} from Rm {William Robotham - Chief Engineer} /Swdl. {Len H. Swindell} c. Da {Bernard Day - Chassis Design} /Jnr. {Charles L. Jenner} c. By {R.W. Bailey - Chief Engineer} /McS. Rm {William Robotham - Chief Engineer} /Swdl. {Len H. Swindell} 4/MH. {M. Huckerby} 3.8.38. BOTTOM TAPPETS. During a recent endurance on a Wraith unit in respect of timing gear wear, two bottom tappets of obsolete type failed on the bottom faces at the thin section around the push rod housing. The section of this type of tappet is pencilled on the attached drawing of the standard Wraith III tappet (IW.1467) and the photograph shows the actual failure. It will be seen that the standard tappet is not recessed around the push rod housing, thus avoiding this thin section, so that the above failure has no bearing on the standard job. The reason, however, in reporting these failures is with regard to the new designs of bottom tappets which have the push rod housing at the top of the tappet, and have been issued for Wraith to ECD.795, Ph.III to ECD.635 and B.60 ECD.329. In respect of Wraith and Ph.III, the push rod base has been housed at the top of the tappet to reduce the length of the push rod to overcome whipping at high engine speeds. Comparing the drawings of the new type of tappets against the failed obsolete type of Wraith tappet, we consider the former should be modified to strengthen both on the bottom and the top faces around the push rod housing and thus avoid the risk of future failures. Rm {William Robotham - Chief Engineer} /Swdl. {Len H. Swindell} | ||
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).