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 characteristics and output performance of Lucas dynamos.
| Identifier | ExFiles\Box 182\M19\ img010 | |
| Date | 5th February 1931 | |
| To:- R.{Sir Henry Royce} from EFC. Cc:- E Cc:- Br.{T. E. Bellringer - Repair Manager} C:- Ph EPC3/ADS.2.31. X.6100. CHARACTERISTICS AND OUTPUT PERFORMANCE OF LUCAS DYNAMOS. This report is the result of having received :- Firstly, from FN, a note FN5/GM.2.3.31 and subsequently as promised in the note an actual Lucas E.60 dynamo No. E1640. and Secondly, a memo H/MEO.1.31 together with blue print LEC.2866 showing output curves of another and different type of Lucas dynamo fitted to a 20 HP. Vauxhall, the principle output curves shown thereon being curves taken on the road as observed by the ammeter and speedometer. For rough comparison with the principle curves there are also drawn on LEC.2866 reproductions of curves we have variously given for both Phantom II high and medium output dynamos and for 20/25 56 coil and 48 coil machines. As E.{Mr Elliott - Chief Engineer} himself observed, the comparison of the curves is more concerned with their shape than with the actual outputs shown, the circumstances in which the various curves were taken being certainly not identical. We have, therefore, principally to make our observations on the fact of the different shape of the Lucas curve as compared with some of the curves we have given for R.R. machines. The Lucas E.60 machine sent by FN, in common with other types of Lucas machines (though not, we believe, all) is, though it makes use of only three brushes, arranged in a different manner as regards its windings than our own machines. The method of utilizing both a fine plain shunt winding and a thick series control winding was long ago adopted by Lucas for the express purpose of overcoming the defects to which the simple third brush single field winding is subject, these being principally :- (1) The falling away of the characteristic curve as the speed is increased over and above that corresponding to peak output. and (2) The variability of the output brought about by irregularities or uncertainties in the bedding of the control brush. | ||