Page:Motors and motor-driving (1902).djvu/191

Rh depress with the fingers all the tremblers except one, allowing each trembler to vibrate separately. Should there be a faulty cylinder, it will at once become apparent, and the cause easily located.

The commutator used on the Napier cars has been placed in front of the driver and covered with glass, so that the sparking at the points is easily viewed. A chain driven off the half-speed shaft causes the centre disc to revolve. A special form of contact is used, which possesses the great advantage of being unaffected by oil. In other respects the system closely follows the Benz.

The Canstatt Daimler Co., Messrs. Mors, &c., are at present using the magneto system.

The following notes on the Mors ignition have been kindly supplied by Lord Cairns:—

The magneto ignition system, which is applied to all the new model motor-engines of M. Mors, consists of a magnetoelectric rotary machine, combined with a series of mechanical contact-breakers.

The magneto-electric machine is bolted to the frame, and driven direct by the gear wheel of the valve cam shaft, which engages with a small pinion on the armature spindle. This pinion is a quarter the diameter of the gear wheel of the cam shaft, and the armature therefore revolves four times to each revolution of the cam shaft, or twice to every revolution of the engine. As two cylinders out of the four fire in each revolution, the magneto thus revolves once for each spark obtained, the correct relative position of the revolving armature being geared to agree with the successive breaks of contact, which being operated by a set of cams on the cam shaft, are thus kept in 'time' with the moments of greatest generation of current.

The breaks of contact are produced in the explosion