The Stanley Show was held in late November, 1909.
A new model Zenith Gradua, showing the improved method of operating the change-speed gear.
3½ h.p. Model: 85 x 88 mm.; m.o.i.v.; Bosch b.b. magneto; B. and B. carburetter, h.b.c.; infinitely variable gears; 2¼ in. Clincher N.S. tyres; V-belt transmission.
Zenith Motors, Ltd., Weybridge.
The 1910 model Zenith has been redesigned throughout and is a great improvement on the 1909 model both in the matter of design of the frame and the operation of the infinitely variable gear. The engine used is one made by Zenith Motors, Ltd., and ha a ball bearing mainshaft and very large valves. A diamond frame is now used very much on the lines of the ordinary motor cycle frame, which spells increased strength. It will be gathered from the illustration below that the method of operating the gear lever is now much handier and the ratio easily altered by means of the handle placed in a convenient position at the top of the tank. The magneto, which is gear driven, is placed at the rear of the cylinder, and is carried on a special platform cast integral with the crank case. The carburetter is situated immediately behind the magneto, so that no flooding, which is almost bound to occur with all carburetters, can drop on to the magneto, which would he likely to cause a conflagration. The lubricating oil pump is placed in an almost horizontal position, so that the amount of oil injected into the engine can be readily seen. A petrol gauge is fitted to the tank, and other refinements include a stand and carrier (the tool case being fitted at the side), handle-bar control levers, Druid spring forks, and large sized tank stoppers. The handle-bars are nicely shaped and brought well back to enable a natural riding position.
Old readers of The Motor Cycle know that with the Gradua gear a variable ratio is given by expanding and contracting the engine pulley by means of a lever, the slack of the belt being taken up by extending the back wheel on specially designed guides. The ratios can be varied between 3 to 1 and 9 to 1. The latter ratio with an efficient 3½ h.p. engine is low enough to enable a motor cycle to climb any hill in the United Kingdom. Another pattern 3½ h.p. motor cycle shown on the stand is the Zenette spring frame, the action of the springs being similar to that of a pair of scissors.
The Motor Cycle, November 22nd 1909 page 926
