« EelmineJätka »
now made in forged Bessemer steel, with the teeth cut out of the solid as in the iron ones.
Owing to the driving power being applied in the centre of the length of the axles, and the forces applied vertically instead of horizontally, there is no side to side oscillation of the engine on the road, which is strongly developed in the ordinary locomotive type of tramway engine, and which, as all tramway engineers well know, is so destructive to the permanent way, especially if not in the first instance laid specially for steam purposes. Another feature is, owing to the fact of the boiler being vertical, there is more range in the water space allowable, and the level of the water is not interfered with so much as in the locomotive kind, when ascending steep gradients, and the water range being so great, it does not necessitate the feed being put on when going up a hill, consequently steam can be easily maintained up to the maximum pressure on the steepest inclines ; for instance, there is daily being worked an incline of 1 in 11, about 400 yards long, with a large inside and outside car with fifty passengers, in the town of Huddersfield, and one of 1 in 13, 880 yards long, at Nottingham, with engines weighing only 84 tons in working trim, starting and stopping on any part of the gradient as required.
The spur wheel on crank shaft being less in diameter than the wheel it drives on the axle, there is a gain of power, and the moving parts of the engines, viz. pistons, connecting rods, guides, &c., are not required to be of the same strength and weight as if coupled direct; further, there is an almost absolute immunity from “ slipping” of the driving wheels, as with this engine it is almost an impossibility to cause “ slipping,” save and except under the most extremely abnormal state of the rails (say snow and frost combined), whereas this "slipping,” which is nearly always present in the ordinary loco type of tram engine, owing to the generally greasy state of the rails, is such a frightful source of expensive repairs owing to the racking strains caused by it on all parts of the mechanism. The result of this immunity from "slipping” is that the same amount of work can be done with an 83-ton engine as can be done with a 12- or 13-ton engine of the loco kind, consequently there is a saying in wear and tear of the permanent way.
In reference to the non-slipping properties of this engine, it is not intended to convey the impression that there is no slipping takes place whatever; the wheels do, slip under abnormal states of the rails, but the slipping is of a slow kind, in contradistinction to the flying round of the wheels of the direct-acting locomotive; this slow slipping is owing to the intervention of the gearing wheels causing such an increase in the piston speed in proportion to the speed of the road wheels revolutions, that the steam from the boiler cannot follow up the pistons fast enough to maintain sufficient pressure to accelerate their speed above a certain point; with the attainment of this result in view, the steam pipes between boiler and cylinders are made so small that they will just give the full boiler pressure on the pistons when going slowly up the steepest gradients with a slow speed, but will not do this when
any attempt at slipping is made, which accelerates the piston speed above the ordinary working rate. Further, with the connecting rods (as in the locomotive proper with outside horizontal cylinders) connected direct to the crank pins, and when at their greatest angle from the centre line, say when the crank pin is on the bottom centre, midway between the dead centres, the tendency is to lift the wheel, axle, and axle box off the rail, momentarily, easing the adhesive load from the rail and setting up the first elements of a slip, which is more and more augmented as the speed of the slip increases, inasmuch as the pulsations are so rapid that the weight of the engine as a whole has not time to re-act through the medium of the springs. This is entirely overcome in the engine under notice by the steam acting on an independent crank shaft carried in rigid bearings which are self-contained with the cylinders.
The intervention of this gearing has another good property, inasmuch as in the ordinary working of tram engines the stoppages have to be made in many cases very suddenly, which in this case is done by simply reversing the valve gear without putting steam against the pistons, which act is in itself enough to “skid” the wheels, owing to the smaller wheel on the crank shaft having to be driven round by the larger wheel on the driving axle, the resistance of the pistons, caused by the amount of compression in the cylinders, being thereby multiplied exactly as the power is multiplied in driving the wheels in the right direction.
The general construction of the framing of engine, the wheels, axles, axle boxes, guard plates, &c., are similar to the loco type of engine. The fire-boxes, are “Farnley,” or “ Low Moor” iron, frames are “B. B. Staffordshire," all bearings and engine brasses are "phosphor bronze," and exceptional care is taken in the workmanship all throughout to ensure its being well done.
The whole machine is cased in with a wrought-iron casing with loose window-frames, which can be moved at pleasure according to the state of the weather, and the engines are fitted with duplicate regulators and reversing levers, also with steam brakes for the cars under the control of the engine-driver, and injectors, so that they can be driven from either end, in which case the engine-man always stands at the front right-hand corner of his engine, whichever way it is running, giving him a good clear view of the road ahead of him.
The wheels have steel tires 2 inches thick, and also steel crank pins for the outside coupling rods; the axles, slide bars, piston rods, crank shaft and cross-head centres are steel, the valve motion "Low Moor” iron, case hardened, all bolts and nuts are steel, turned to fit in bored and reamered holes.
June 23, 1883,
Mr. CHARLES JONES, President, in the Chair.
The minutes of the previous meeting having been read and confirmed, the President referred to the intimation that Mr. Thomson had given of his desire to resign the Hon. District Secretaryship, but trusted that that gentleman, who had given every satisfaction, would reconsider his intention. And in case the next Annual Meeting should be held in the North, Mr. Thomson's services would be most valuable to the Association.
Other speakers having expressed the same views, Mr. Thomson stated that he had not discharged his duties to the district as he should have liked, owing to the increase of official duties, but if the next Annual Meeting were to be held at Newcastle, he would be willing to remain in office till after that event.
The PRESIDENT said the first subject for consideration was the résumé of a discussion on Mr. James Hall's paper on
APPORTIONMENTS OF PRIVATE
The PRESIDENT: Perhaps Mr. Hall will kindly preface the discussion with some remarks by way of a beginning.
Mr. JAMES HALL: I have very little to say. I would, however, draw attention to the Public Health Act Amendment Bill. There are several clauses in that Bill which would, I think, be the better for amendment. Last year, Mr. President, you made reference to such a measure, and said that it would be well, in framing it, to
* This paper was read and partly discussed at a District Meeting held atSunderland, April 22, 1882. See vol. viii. of. Proceedings,' p. 70.