Ineffectiveness of the Wraith cam balancer in relation to timing gear wear and low-speed rattle.
| Identifier | ExFiles\Box 7\8\ X 607 Camshaft-page26 | |
| Date | 13th April 1938 | |
| 607. COPY. Hs. {Lord Ernest Hives - Chair} from Hm. {Capt. W. Hallam - Head Repairs} c. Ry. c. RBC. c. Da. {Bernard Day - Chassis Design} c. Mx. {John H Maddocks - Chief Proving Officer} c. LA. {L. A. Archer} Rm {William Robotham - Chief Engineer} 8/R.13.4.38. WRAITH CAM BALANCER. The Wraith timing gears only wear badly at high speeds. It can be shown mathematically (Hm {Capt. W. Hallam - Head Repairs} /PJH.4/MH. {M. Huckerby} 11.4.38. attached) that a cam balancer correctly adjusted for low speeds not only does not reduce the high speed load on the gears, but actually increases it. Therefore, the cam balancer can only be detrimental to the wear which has taken place on Wraith timing gears. With regard to the low speed rattle which results from the wear on the gears, it will be seen from the attached reports that:- (1) The Wraith valve gear has so much internal friction that it automatically damps out the camshaft oscillations. (2) This is further proved by the fact that, as long as the camwheel wear is regular, there is no rattle from the timing gears, even when no cam balancer is fitted. (3) A practical demonstration of the ineffectiveness of the cam balancer on the Wraith has been obtained by trying with and without it on six Wraith engines. No difference could be detected. The plunger which exe(Aero Engine)rts an end load on the camshaft, was introduced because the new type of Wraith tappets exe(Aero Engine)rt an end thrust on the camshaft. This causes the camshaft to move endways at low speeds and make a noise. So far the plunger has been completely successful in eliminating this noise. We attach reports from Hm {Capt. W. Hallam - Head Repairs} /Swdl. {Len H. Swindell} and Rm {William Robotham - Chief Engineer} /PJH which go into detail regarding the points raised. | ||
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).