Steep Gradient Locomotives.

Bruce Herald, Volume IX, Issue 806, 26 May 1876, Page 3

Steep Gradient Locomotives.

The New Zealand railways being, as is pretty well known, laid over hills with some rather severe, inclines have to be worked on a somewhat similar system to that employed on the Moat Cenis railway. The guage is 3 feet 0 inches, and there is a central rail at an elevation of O.V inches above the level of the two outer ones constituting Mr Pell's system. The Government has ordered four locomotives of an improved type, which are now being made from their own designs by the Avonside Engine Company (limited), of .Bristol. So much thought has been expended on the engines, and so many special contrivances introduced, producing in the end so splendid a result, that Mr John C. Wilson, the engineering and general manager of the Avonside Company, has every reason to congratulate himself on his work. On Saturday last, one of the locomotives was tried on a short temporary line of railway, laid down in the yard of the Bristol Waggon Works, by the kind permission of Mr Pry, the managing director. Here teats of every imaginable description were applied, and the results were uniformly satisfactory. The line was too short, however, to make any experiments such as those tried by the Kailway Accident Commission, at Newark, much to the regret of the spectators, as the brake answered so admirably that it would have been interesting to learn exactly how short the distance really was in which the engine was stopped against full steam.

The length over-all of the locomotive is 21 feet G inches, and its width 9 feet 3 inches. It is driven by two pairs of wheels, coupled, of 2 feet 3 inches diameter, on which about 28 tona of the weight rest, and the trailing wheels are 2 feet G inches diameter, carrying about G tons, the total weight of the engine being about 3i tons. The trailing wheels are fitted with the "radial axle boxes " patented by Mr 11. "W". Widmark, of Bristol. These are intended to provide for the easy turning of curves, and are adopted in this instance to curves of the short radius of 300 feet. They are provided with cylindrical guides, and with planes set at an angle to the central lino of the axle, while at the top are inclined planes calculated to give much elasticity. We understand that these asle boxe? have given good results in working, and on Saturday it was evident that a considerable amount of play waa given as the engine rounded tho curves of the experimental line. Tbe boiler is arranged for a variation in wate? level corresponding to an inclination of 1 foot in 12, this being the steepest slope on the New Zealand lines. It has 170 tuhe3 of If inches diameter and pitch of 2 7-1G inches. The grate area is 13 squire feet, and tho heatiqg surface of the five-box 74; square feet, that of the tubes being 738 square feet, affording a total ot 957 square feet. The tanks hqld Gl-i gallons, and the coal boj: has a capacity of 86 cubic feet. The driving engine for the vertical or ordinary j wheels consists of a couple of cylinders ' of 14-in.cb, diameter and 1G inch stroke, while a smaller pair of cylinders of 12---inch diameter and 14-inch stroke work the four horizontal wheels of 22 \ -inch diameter which grip tbo contral rail. These may bo called tho outer and inner engines respectively, and the gearing is so arranged that either may be worked separately, or they may be worked simultaneously, either in, hawuouy or antagonism. Twq pairs of volute springs keep tiits horizontal wheels apart, while a couple of powerful oreaoenfc springs exert a pressuws of twenty-eight tons to bring them together. This is, of course, the useful pressure upon xho centre rail, while a corresponding amount is exerted upon the driving wheels, thus giving the . Ifo'ge quantity of 50 tons useful adhesion for a 31 ton locomotive. The valve motion far the inside (Fell) engine is an : adaptation of Walsebiirt'a system. The brakes are double — the ordinary lever brake being fitted ta the driving wheel?, whilst » highly efficient brak.e ia fitted to the. central rail, gripping it like a. pair of nutcrackers. Another noteworthy miuor feature is a j peculiar link-motion in the coupling, whicn is Stradal's, and ia so arranged that even with the utmost lateral motion a pull always lakes effect on the central line of the vehicle. These locomotives are intended to work in pairs, being coupled end to end, bo that the drivers work together, with one stoker between them, and they are calculated to draw 100 tons up an incline of 1 in 15 at a rate of five miles an hour. The following are the principal results of Saturday's trial .• — 1. Either engine alone was sufficient to drive the locomotive, ar.d a J'orliori together drove her admirably. 2. The engines being set to work against each other, ie, the outer ones being driven forward and the inner ones reversed, the latter gripping the central rail proved to bo more powerful. 3. Both engines being at work, the brake power was sufficient to stop the whilst a highly efficient brake is fitted to locomotive — steam being full on at 1251bs — within three or four times her own length. — < Jron,' February 19,