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intendent of Motive Power of that road, Mr. H. F. Ball:
"In reference to the Walschaert valve gear, engine No. 912 has now a total of to inch lost motion in the valves. This is the total lost motion in the whole motion work; the engine has made, approximately, 39,000 miles. Engine No. 5924 (with link motion), examined the same date, had y inch lost motion in the valvestem, and has made, approximately, 32,000 miles. This seems to be very much in favor of the Walschaert valve motion.”
As to smoothness of operation, it is only necessary to understand the construction of the Walschaert gear and to compare it with the double eccentric motion, or to watch it in action, to realize its niceness of operation.
Removing the valve gear from between the frames permits a cleared inside space for other uses that has always been wished for. One of the common causes of engine failures in recent years has been weak engine frames, very often resulting in their breaking. At the very point where strong cross-bracing is necessary, between the cylinder casting and main driving-axlethere has been no room for it, the space having been taken up by the eccentric and link mechanism. With the Walschaert gear, as much heavy frame bracing as is desired may be put in-or anything else. There are engines like that of the Erie motor car, previously illustrated, where much inside space is needed for the spring arrangement and main car-body bearing.
Some very heavy Atlantic type passenger engines with the Stephenson link motion were received by a certain road, and trouble that was experienced at the start from hot driving-boxes never ceased. The underneath construction of these engines compelled placing the links in such a position that the eccentrics, to be in line, were crowded outward, making necessary the use of a too narrow driving-box, and a brass of insufficient bearing surface for the great weight that it had to support. The next delivery of engines to that road were of the same class except that they had the Walschaert valve gear, and wider driving-boxes that had bearing surfaces proportionate to the weight of the engine, and these engines ran cool from the first trip. Nothing about the engine needs to be sacrificed to make room for the Walschaert valve gear.
The improved design of the De Glehn Balanced Compound has been adopted by the American Locomotive Company, and the Baldwin Locomotive Works, in their Cole, and Vauclain, balanced compound engines, respectively, and in each of which a crankaxle is a principle feature. The manufacture of this type of engine is increasing in America since European practice has shown us the absence of danger from that bugaboo—the crank-axle. Instead of crowding four eccentrics and the rest of the valve motion—with its heavy interference with perfect balance—among the gear of the inside engines, it can be replaced, as with the De Glehn engine, with the lighter, more accurate, Walschaert gear on the outside of the frame and wheels.
The possibilities that lie in the use of this valve gear are not generally realized in this country; it can be applied to engines of any type without material alteration, and without the use of transmission mechanism. The line of motion is nearly straight, and the longer the eccentric rod and radius rod—the greater their radius—the more perfect will be their work. Europeans know these things; they seem to believe, also, that the desired results from the use of this valve motion are best secured in connection with the outside admission, D-slide valve. On the main lines of Continental Europe 90 per cent of the engines are equipped with the Walschaert gear, and the remaining 10 per cent represents but a fraction of Stephenson link motion. At the Liège Exposition, out of 31 engines on exhibition, 25 were fitted with the Walschaert valve gear.
Its adaptability is great. If it is desirable, in order to simplify the reversing mechanism on any particular type of engine, to raise the radius rod and link-block
when the reverse lever is thrown forward, it will only be necessary to change the position of the eccentric 180 degrees-from a quarter ahead of the main-pin, with outside admission valves, to a quarter behind the pin.
And now, as one of the chief peculiarities of the Walschaert gear lies in the manner in which lead is secured, and maintained unchanged throughout the different points of cut-off, the general effects of lead are worthy of speculation. Self-opinioned men, men who think for themselves and are not too over-conservative, are beginning to question if the advance of the valve, any further than is necessary to overcome the steam lap, is really a help or a hindrance. If not a help, can it fail to be a hindrance? There doesn't seem to be any reason why, with any class of engine in any branch of service, the amount of lead opening in full gear should increase as the speed increases, as does occur when the engine with the Stephenson link motion is hooked up. With the Walschaert gear the amount of lead suitable to the speed at which a particular engine will be expected to run or the work it will be required to do can be decided upon and the valve advanced to permit that opening, and that lead remains positive, unaffected by hooking-up, and almost entirely free from the shifting of results due to lost motion and vibration.
An expert on valve motion has the following to say in regard to this question; it is an extract from an article in one of our leading technical journals:
“Opinion has grown, as error is apt to grow, that an admission of steam is absolutely necessary to create a cushion upon which the piston and connections may gradually come to rest before beginning the return stroke. Those who are accustomed with the running of locomotives know that when the throttle valve is closed the rods and reciprocating parts run smoothly, even if loose. No pounding is observable at any rate of speed.
"Is it not reasonable to expect that the piston meeting with steam resistance before it has completed its stroke should rudely affect the bearings of the rods and crank-pins, and induce an excess of friction ? It has been repeatedly shown that if the pre-admission of steam amounts to a sufficient quantity to cause compression, a marked increase in steam consumption is shown.
“The real need is the readiness of admission of steam at the time when it is required to move the piston in the other direction, and while the ordinary valve has this advantage in a marked degree, this rapidity of opening compensates in some degree for its other defects.
“Assuming, however, that lead is desirable for slightly cushioning the piston while the working parts of the