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).
Tests conducted on phosphor-bronze dynamo cut-out springs.
| Identifier | ExFiles\Box 50\1\ Scan142 | |
| Date | 14th September 1932 | |
| X6042 To By. {R.W. Bailey - Chief Engineer} from Hs {Lord Ernest Hives - Chair} /Pgt. c. E. {Mr Elliott - Chief Engineer} By {R.W. Bailey - Chief Engineer} /RD. Hs {Lord Ernest Hives - Chair} /Pgt.11/XT.14.9.32. PHOSPHOR-BRONZE DYNAMO CUT-OUT SPRINGS. Tests on cut-out springs made in phosphor-bronze were initiated as the result of a desire to dispense with the black enamel, used to cover the standard spring. This spring, at present, is made of steel, and it was thought that irregularities in the thickness of the enamel coating, probably accounted for the variations, which occurred at times, in the operation of cut-outs. Two cut-outs fitted with phosphor-bronze springs have been well tested out on cars; one having run for 21,300 miles, and the other 27,370 miles. A third is still running. From the bench tests, which followed their removal from the cars, it was found that in both cases the voltage required to operate, had fallen considerably. Cut-outs are set to operate at about 12.5 volts, and this had fallen, with one, to 10.3 volts, and with the other, to 10.2 volts. Also the contact points on both were badly burned. From this we conclude that the controlling springs had weakened. The burning of the contact points is what we would expect as the result of a cut-out operating at too low a voltage. A tendency for the spring to weaken in this manner, has been observed with the standard cut out having the steel springs. We therefore propose keeping the standard unit under closer observation, together with the third one fitted with a phosphor-bronze spring. Apart from this we do not think it worth while going any further with the phosphor-bronze spring, as in any case with the contemplated use of a voltage regulator very shortly, the cut-out unit will be entirely redesigned. Hs {Lord Ernest Hives - Chair} /C.A.Pignatt. | ||