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).
The Smith (T & M) Type 'A' Dynamo.
| Identifier | WestWitteringFiles\C\August1919\ Scan39 | |
| Date | 13th August 1919 | |
| R.R. 235 A (100 T) (S.F. 575, 16-4-19) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2354. To R.{Sir Henry Royce} from EFC. c. to CJ. c. to Bn.{W.O. Bentley / Mr Barrington} c. to E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} c. to EP.{G. Eric Platford - Chief Quality Engineer} c. to Da.{Bernard Day - Chassis Design} c. to EH. ORIGINAL. THE SMITH (T & M) TYPE 'A' DYNAMO. The field carcase of the dynamo is of cast iron, of outside dimensions 5.69" dia. by 6.75" long, the thickness of the shell being .375". There are two laminated poles bolted to the inside of the carcase. Particulars of armature, commutator, brushes, field winding, etc., were given in a table under cover of our previous report EFC4/T12.5.19 on the Smith dynamos. The machine has a plain single field winding, half of this on each pole, the control being carried out entirely in the armature by means of a scheme of brushes arranged and connected up as described below, and diagrammatically illustrated on sheet F.{Mr Friese} The original Trier & Martin scheme consisted in the first instance of a plain shunt wound two-pole dynamo with main brushes M + and M.{Mr Moon / Mr Moore} - (see diagram below) exactly in the neutral position. There were then added two auxiliary brushes A + and A - exactly at 90° to these, i.e. in the positions on the commutator corresponding to those of maximum activity in the armature. Each of these auxiliary brushes was connected through a resistance R to the corresponding main brush 90° behind it, considering the direction of rotation as the forward direction. The action of the machine was as follows:- During the period between starting up and the point at which the dynamo was connected (by the cut-out to the battery,) | ||