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).
Specifications for building an armature, including materials, winding, and testing procedures.
| Identifier | WestWitteringFiles\D\March1920\ Scan23 | |
| Date | 1st March 1920 | |
| To CK.{Mr Clark} from R.{Sir Henry Royce} -2- R6/G22/3/20 Contd. Mica is used between the plates to avoid the turning over of the plates due to milling the armature grooves after the armatures are built up. A special caution to prevent the milling cutter running is made by taking about one-third of the depth of the groove at a time. The bottom of the groove would have a half-round end. The middle of the armature would be turned down to provide for the fine steel band in the centre of its length. The end wiring should be double helical, and should be fitted on to a support and bound down with steel wire so that the maximum speed of 4500 would not be likely to disturb the coils. The size of the wire to be used on the armature would be .040" or larger if found possible without undue tightness. The insulation would be fine double cotton covered, not adding to the diameter of the wire more than .010". The insulation would be manilla paper troughs fitting into the former, which is temporarily secured by tapes, and after removing from the former the whole coil is taped with fine cotton or silk tape, and well dried and varnished before putting on to the armature. The coils would be wound so as to form two outside ends, one at the bottom and one at the top of the coil, which would form another helical layer, and permit of the coils being conveniently connected up as wave winding. The dynamo would be tested with high resistance graphite carbon brushes, not low resistance copper Morganite brush. It is intended to test these dynamos with trembler control, for which purpose the Bijur was given to rewind suitable for 12 volt and 12 ampere circuit. (contd.) | ||