The Caprotti Valve Gear.

Refinements are constantly being introduced in locomotive design, and every year sees some new item of equipment brought into use to increase locomotive efficiency and economy. The latest development in this direction at Home is the experimental utilisation by the London, Midland and Scottish Company of the Caprott. valve gear on its engines. The main difference between the Caprotti and the familiar Walschaert gear is the employment in the Caprotti equipment of poppet (or automobile type) valves for the admission and exhaust of the steam. These valves, of which there are sixteen (one admission and one exhaust for each end of each cylinder) are operated by two valve boxes, worked by a short cross shaft under the smoke-box, bevel gears driving this cross shaft from the longitudinal shaft which is housed in an oil-tight gear box. The drive of the cross shaft is taken from the intermediate wheels of the locomotive, on the same principle as the back axle and propeller shaft of a motor car.

Revolving cams operate the valves through a series of rocker arms, which depress the valve

The First Touch of Winter.
Heavy anowfalls only occasionally hamper railway operations in Britain. Further north, however, in snow-bound Scandinavia, much more severe climatic conditions are experienced at Christmas time. Above is depicted the first snowfall of the season on the newly electrified tracks of the Swedish State Railways between Stockholm and Gothenburg. This electrification operates on single-phase current at a frequency of 16⅔ with 16,000 volts on trolley line.

page 20 spindles, a single cam operating the exhaust, and double cams operating the admission. These double cams are so arranged that their largest diameters can be revolved so as to more nearly coincide, or the reverse, by movement of connected scrolls along a quick left-handed threaded shaft, which runs on ball-bearings, this movement being under the control of the driver. The action of these two cams is such that while the “lead” is always constant, the time period during which the valve is open can be altered without changing the amount of lift, this having the great advantage that “notching up” does not result in wire drawing, nearly full boiler pressure being secured in the cylinders to an early point of cut off.

Results achieved to date on the London, Midland and Scottish Railway show that the Caprotti equipment possesses great possibilities for fuel consumption economy and reduced maintenance costs.

Manchester-Bury (L. M. & C.) Electric Division.