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).
Modifications to resolve a fault in trafficators not retracting at high speeds.
| Identifier | ExFiles\Box 166\6\ img038 | |
| Date | 4th March 1941 | |
| To Ba/SAC. from Rm{William Robotham - Chief Engineer}/HC. Copy to Mr. Ev{Ivan Evernden - coachwork}/JD.{J. Draper - Frames} Elec 6073 Rm{William Robotham - Chief Engineer}/HC.vT.4.3.41. TRAFFICATORS. ------------ Further to the two kinds of failures outlined in our Rm{William Robotham - Chief Engineer}/HC.5/ET.3.2.41, all our trafficators, when used in conjunction with a time switch, have a rather serious fault, in that, if, after using a trafficator the car speed is allowed to rise above 50 m.p.h., before the time switch cuts out, then the arm will not fall into its "OFF" position, until the speed falls to about 20 m.p.h. In order to eliminate this trouble, we have tried a number of modifications on the trafficators of 9.B.V, and have finally effected a cure by attaching a light wooden vane, or fin, to the outer edge of the arm (see fig.2). If accepted, this could easily be made a production job, since the outer edge of the arm is normally covered by a thin metal pressing, and all that is required is an alteration of its contour. The following modifications were tested:- 1 - Reduction of the frontal area of the arm by 20% (fig.1). 2 - Setting back of the trafficator 1/4" in the door pillar. 3 - Small metal vane, 0.6 sq.in. in area attached to outer edge of the arm (fig.1). 4 - Long narrow wooden fin attached to the outer edge of the arm (fig.2). RESULTS. - 1 and 2 gave no improvement. 3 and 4 cured the trouble; with either of these modifications, the arms functioned perfectly, even at a car speed of 85 m.p.h. No advantage can be attributed to extra weight on the arm, since the weight of the metal vane is negligible (approx. 2 to 3 gm). We recommend scheme 4 since scheme 3 would not be acceptable to the body designers. It is possible that an improvement would be obtained by alteration of the inner edge of the arm instead of the outer edge, i.e. by making the edge square instead of half round, as in the existing arms. The latter would mean an alteration of the bakelite mould. Rm{William Robotham - Chief Engineer}/HC. | ||