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).
Continuation comparing the performance of 19-slot armatures with standard ones.
| Identifier | WestWitteringFiles\N\July1925-September1925\ Scan137 | |
| Date | 26th August 1925 | |
| R.R. 493A (50H) (D.B. 175 25-9-24) J.H.D. -3- EXPERIMENTAL REPORT. Contd. Expl. No. 4121 REF:FCL/T26.8.25. has been particularly good. Further points in connection with these tests are contained in the following quotation from my assistant's report:- "The 19 slot armature affords an easier magnetic path than the standard, and hence gives a better and more output in the early stages, cutting-in; but the improvement is not so marked in the case of the .022" air gap where the cutting in speeds for both armatures all lie between 705 and 730 r.p.m., upwards of 65 r.p.m. late (to specification). The peaks are sharper and about 200 r.p.m. earlier for the 19 slot armature than for the standard, but reach to within about half an ampere of the same values. The peaks for the .022" gap are high (mostly over 13.0 ∝) and correspondingly later (1810 - 2040 r.p.m.) and the outputs are well maintained at high speeds. In all cases the output remains up at high speeds, better with the 29 slot armature than with the 19 slot. In no case, however, does the value fall below specfn. On the whole, the most useful arrangement is (5) probably that with the 19 slot armature, .015" air gap and 11° of main brush retard. Although thisxxxxxxxxx very xxxxxxxxxx cutting-in, it provides an output of ample peak value and sufficiently sustained at high speeds. (On the curves the high speed output is lower for the 11° | ||