Alley and MacLellan, Limited.
Page 13
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Exhibit: 5-ton and 6-ton "Sentinel" Steam Wagons, and Parts.
The wagons which are staged by Alley aneMacLellan, Limited, of the Sentinel Works, Polmadie, Glasgow, are distinct from all other steam wagon exhibits at this show. This make of vehicle is not fitted with a compound engine, such as is usually fitted to steam wagons and tractors, but it has a special form of simple, double-acting, two-cylinder engine of distinctly novel design. The steam is admitted into the cylinders through cam-operated, poppet valves, and the distribution of the steam is altered by causing the camshaft to be moved along in the direction of its length, and in this way to bring different parts of the cams to act on the steam and .exhaust valves. The details of this engine, and also of the boiler which supplies the steam for its working, were illustrated and described in "THE COMMERCIAL MOTOR" for the 22nd March, tgo6, and, since that date, but little alteration has been made to the details of the designs.
The foot-operated, steam regulator which is fitted to all the Sentinel steam wagons is a very useful device, as it enables the wagon to be controlled with the same amount of ease, and in much the same mariner, as a petrolengined wagon : when it is desirable that the driving power should be cut off instantly from the road wheels, the steam supply to the engine can be interrupted by a motion of the foot lever, in the same way that the clutch of a petrol vehicle would be withdrawn.
The illustration given on this page shows the company's latest driving wheel, as fitted on its six-ton model; the steel tire has a series of holes drilled through it, and these holes are spaced along a zig-zag line, in such a manner that not more than one-eighth of the total width of the tire is cut away at any point along its circumference. The same illustration also shows the differential locking gear, which is fitted to one of the driving wheels. When it is required that both the driving wheels should be positively locked together, the spring pin (A) is withdrawn, and this action allows the pawl 03) to fall until it engages in one of the notches in the locking collar, which latter is firmly secured to the axle. The success which attended the intro
duction of the six-ton model has led the maker to construct a lighter model, designed on the same lines, and built to deal with a load of three tons. Th;s wagon can carry three tons at an allow: able speed of eight miles an hour, if its wheels are shod with steel tires, but, if provided with rubber tires, as is the one shown on the Sentinel stand, the allowable speed is 12 miles an hour. This increased speed is of great importance to town users, especially to brewers. The three-ton wagon which is exhibited by this company has been sold to Robert Deuchar, Limited, of Sandyford Road, Newcastle-on-Tyne, and is a repeat order. This company's first six-tonner, also of the Sentinel make, was examined and tested, by the Engineering Department of "THE COMMERCIAL MOTOR," prior to its acceptance as a vehicle suitable for its requirements.