CAV electrics

Sir,

Possibly it might be of interest to enlarge a little on the early car electrics mentioned in the first part of the letter from your Kenya correspondent, Mr. Solly. As he mentions, the early CAV system did not employ a cutout, and the dynamo ran as a motor, when the engine speed dropped below its “motoring” speed. However it did not try to drive the engine! In the pulley was incorporated a free wheel, just like a pedal cycle back sprocket. This was arranged to make quite a racket, to remind one to switch it off when leaving the car—all these systems had a switch incorporated, there being no other way of disconnecting the dynamo from the battery. I think Mr. Solly must mean the current flowed back from the battery to the dynamo, this certainly does not run backwards—the engine would not take kindly to such antics!

I was surprised to read that the Wolseley mentioned, in spite of having all the electric lighting and charging gear, did not have an electric starter. In 1914 this was CAV’s latest device. It consisted of a motor-version of their generator, with an epicyclic reduction incorporated in the front end, which was mounted about half-way back down the chassis, from whence a long shaft ran forward to terminate in a leather-faced flat pulley, which for the purpose of rotating the engine, was held in contact with the periphery of the flywheel by a pedal usually to the left of the clutch. Having thus engaged the drive, one then pushed a switch of substantial proportions, which one hoped then persuaded the motor to turn the engine. In fact with cars with a fairly low compression-ratio, such as our 1914 sleeve-valve Daimler, it works very well, and there is never the problem of being at top-dead-centre as can occur with four-cylinder cars using compressed air starters.

Crosby.
R. J. Evans.