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).
Continuing the analysis of performance curves for standard and special armatures with varying air gaps.
| Identifier | WestWitteringFiles\N\July1925-September1925\ Scan136 | |
| Date | 26th September 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. -2- EXPERIMENTAL REPORT. Contd. Expl. No. 4121 REF: EFC1/T26.9.25. The curves given are for a .015" air gap. Experiments have also been made on both standard and special armatures with a .022" air gap, but in the 20 HP. case (unlike the EAC. case) no advantage has been found in the extra air gap, and the curves are not issued. Referring to the present curves, (1) and (2) are for the standard armature, whilst (3), (4) and (5) are for the special armature. This latter shows some advantage in the early stages of the curve, where charging current is valuable. There is also given (6) on this sheet, a repetition of the representative output curve of the HO HP. dynamo which has previously been issued. The positions of the main brushes and control brush are in all cases given with the curves. The performances of (1) (2) (3) (4) and (5) are bigger than (6), largely for the reason that whereas in these later tests a larger maximum temperature rise, e.g. 55°, has, as in the case of the EAC. machine referred to in our EFC1/T28.5.25, been allowed. Two 29 slot machines and one 19 slot machine with brushes set in accordance with these tests are now being prepared for running on experimental chassis. In spite of the somewhat increased performance over the previous representative standard, the commutation in all cases | ||