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).
Alterations to the 20 HP dynamo specification.
| Identifier | ExFiles\Box 165\6\ img045 | |
| Date | 15th December 1926 | |
| X5660 To EY. SFT{Mr Swift}/Mr. Brock. c. EY/RD. EFC11/T15.12.26. X.5660. 20 HP. DYNAMO. X.5781do. We require a small alteration to the position of the control brush on the 20 H.P. dynamos, by which the angular distance between the centre line of the control brush and the centre line of the positive brush becomes on the average 121° in place of 120° as at present, and at the same time the distance of the trailing edge of the control brush from the leading edge of the main positive brush should measure on the average precisely 17 commutator segments. Will you please alter the figure of 16 1/2 segments in sub-para. (d) of para. (1) of the Specification of Production and Test of the 20 HP. dynamo, dated 18.10.26, to 17 segments exactly, and arrange to produce future machines with this slight alteration of setting. The rest of the specification of test will be unaffected with the exception of para. (5), where the output limits should be changed to 9.5 and 10.5 amperes. In order that the output in the circumstances stated on the test sheets shall fall between the limits given, it can be understood that a small subsequent alteration of the control brush position, say of ± 1° on the 121° given, is permissible to accommodate slight differences in the machines. EFC. | ||