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).
Dynamo output, a 'half charge scheme', and comparing it with a Lucas dynamo.
| Identifier | ExFiles\Box 163\6\ img127 | |
| Date | 20th January 1931 | |
| HS.{Lord Ernest Hives - Chair} FROM E.{Mr Elliott - Chief Engineer} EFC X.6016 E1/M20.1.31. C. to SG.{Arthur F. Sidgreaves - MD} R.{Sir Henry Royce} WOR.{Arthur Wormald - General Works Manager} C. to PN.{Mr Northey} DY.{F R Danby} MX.{John H Maddocks - Chief Proving Officer} X.6016 DYNAMO OUTPUT. X.6100 Referring to HS{Lord Ernest Hives - Chair}/GWH{George W. Hancock - Head Chateauroux}6/KT16131.-item (21) Dynamo- we should like to comment on the reference to "the failure of the half charge scheme" as we believe there exists a certain amount of misunderstanding with reference to this matter. Early correspondence in connection with the scheme shews that the primary object was to boost up the output of the dynamo when the head lamps were alight to avoid the very big discharge that was taking place due to the use of headlamp bulbs consuming 11 amps. on a system that had been designed for 6. Naturally it was necessary to reduce the dynamo output with the headlamps out of action but this second rate of charge was intended to be quite considerable. It should be realised that we are getting more output from the dynamo than we otherwise should by reason of the two charge scheme, as the lower rate of charge as at present fixed is equivalent to a normal output with the difference that it cuts in about 1 MPH. later. The limitation we are up against appears to be in the dynamo itself. We attach herewith some output curves - LeC. 2866 - taken on the road from a Lucas dynamo fitted to a 20HP. Vauxhall with car warmed up. The normal output of this machine is given as 12 amps. but it has been boosted up by adjustment of the 3rd. brush to a higher output for the purpose of carrying more powerful headlights as described in our memo. E1/M241230., and has been running thus adjusted for over a year. A two rate charge scheme is incorporated (not interconnected with the lights) but with the dynamo boosted up, the lower rate of charge cutting in at 12 MPH. has been used generally for the daytime running. The dynamo is a concentric machine of the same dia. as the 25HP. RR. dynamo but about .5" shorter. The point to which we would draw particular attention is the way in which the Lucas dynamo cuts in early, and yet maintains its output at high speeds. The RR. curves are only shewn for the purpose of comparing shape. It would be unfair to compare the actual outputs without establishing that the conditions are the same. E.{Mr Elliott - Chief Engineer} | ||