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).
Intended rubbing action of the spring in a distribution box cutout.
| Identifier | ExFiles\Box 65\2\ scan0089 | |
| Date | 3rd June 1925 | |
| X7740 To EY/RD. from EFC. {E. Fowler Clarke - Electrical Engineer} c. Mr. Brock. EFC {E. Fowler Clarke - Electrical Engineer} 5/T3.6.25. X.8740. DISTRIBUTION BOX. X4105C Referring to Mr. Brock's note of the 26th ult. and your EY/RD1/ML27.5.25, first of all we want a definite rubbing action - mere rolling is not sufficient. We confirm that it is intended that the tip of the spring carrying the upper contact should, in operation, be lifted off the armature; in fact the pressure of the tip of this spring on the armature should be very light when the contacts are separated. The spring should then be such that a definite rubbing action is observable in operation when the cutout cuts in, and further than this, a further rubbing action should be observable as the increasing output of the dynamo increases the current in the series coil. This effect has been observed on the cutout incorporating the experimental modification of the rigid plate on the top of the standard spring, together with the rigid fixed contact point support, and also on another cutout with a weaker spring (only). In these cases the cutout was carefully adjusted for small pressure of the tip of the spring on the armature and in each case the result after several hundred miles running appears highly satisfactory. We agree with Mr. Brock that it is not easy to get this effect with the standard spring, but our Contd. | ||