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(7) Frame Bracing. The removal of the valve gear from between the driving wheels facilitates bracing the frames of the locomotive laterally.
(8) Unvarying Advance of the Valve. Lead, if present, is not altered by hooking-up the link.
(9) The General Adoption of Walschaert Gear Throughout Continental Europe. Its use there for over half a century.
As to accessibility, everything is in favor of the Walschaert motion. The common link motion is crowded in between the frames where it is very hard to get at; the space that it occupies could well be used for other purposes, and the valve gear requires too much attention to be stowed away in a somewhat inaccessible place. When break-downs occur on the road, time is lost in doing repair work, or in disconnecting, in the confined space inside the frame; and in the shop, the locomotive with the Stephenson gear requires considerably more time to have its valve gear set up correctly than does the engine equipped with the Walschaert motion. Imperfectly lubricated machinery is expensive, and the oil used on railroads represents a large sum annually. The double eccentrics require a large amount of oil, but their location invites carelessness in getting it properly applied, and the monthly strictures against the men as to the amount used results in an over-economy; the effect is that the eccentrics run hot and trains are delayed. I was fireman on an engine when an eccentric strap broke and a hole was punched through the water leg of the firebox, not only disabling our engine, but, through the complexity of train operation, delaying and tying-up other trains until the business of the whole division was disorganized. Oil was hard to get and hard to put on, else the trouble would not have occurred, but it could not have happened if our engine had been equipped with the Walschaert gear.
No matter how conscientious the engineer may be, it is a well-known fact that machinery placed where it can be gotten at is taken better care of, both as regards oiling and inspection, than where it is put in an out-of-the way and crowded place.
It is not uncommon for the valves to get "dry” on account of the lubricator choking, or becoming empty; in such cases the tremendous resistance of the valve under steam pressure throws increased labor upon the eccentrics that would have but very little tendency to over-heat the turned pin of the Walschaert gear; but the location of the Stephenson eccentrics hides from the engineman the first symptoms of trouble, and afterward stands in the way of receiving proper relief.
The amount that the Walschaert gear saves in weight over the common link motion is rather startling, being in some cases very close to one-half. The motion, from eccentric to valve, on a big, modern passenger engine is continually tearing itself to pieces. Is there any wonder due, when one considers the weight of it all, and that the joint action of two opposing eccentrics are throwing the link and transmission mechanism in one direction to be instantly stopped, started, thrown the opposite way and stopped-only to be re-started and stopped again-and so on with the rapidity engendered by a speed of seventy or more miles an hour? It is a wonder that eccentric straps, rods, bolts, etc., stand the strain at all, and a weight of metal must be there to give strength to the parts that is one of the principal reasons for the adoption of the Walschaert gear on so many newly built engines; the load has been lightened.
“It is understood that the Walschaert gear was applied to the Lake Shore & Michigan Southern · Railway locomotives at the suggestion of The American
Locomotive Company, to whom belongs the credit for the present tendency toward the introduction of this gear in this country.”-American Engineer and Railroad Journal.
Now, therefore, as the above-named road has purchased a great many new engines of various types, and as a number of those engines of each type has been furnished with the Walschaert valve gear while the others have the Stephenson link, it is possible to show the figures regarding the weights, proportionately, of the two gears, on engines that are in all other respects exactly alike.
Following, in parallel column, are presented in detail the weights of the several parts of the valve gears, Stephenson and Walschaert, of the L. S. & M. S.-New York Central, Class D, 2-8-0 freight engines, built by the American Locomotive Company:
260. Rocker boxes
240. Transmission bar
300. Transmission-bar hanger
140 72 70 220
One thousand two hundred eighty-three pounds is a tremendous weight to be included unnecessarily in rapid-acting machinery; especially when the deflection of one-thirty-second of an inch may change the motion sufficiently to blind one of the events-lead, for instance. And in substituting the Walschaert gear it means cutting off thirty-five (35) per cent of the weight of the old link motion.
But some of the above are fixed, immovable parts. If we want to find the difference in weight of the working parts we should cut out such as the reversing shaft, rocker boxes, link support (Walschaert), etc., and we then find the weight of the Stephenson motion gear to be 3,120 pounds, and that of the Walschaert gear 1,702 pounds—a saving in weight of the parts that thrust and take of 1,418 pounds, amounting to the still more interesting figure of over forty-five (45)
Of the heaviest passenger engines ever built, at this date,—the class shown in Fig. 19-some have Stephenson link, and some the Walschaert gear. The comparative weights of the valve gears of this class, J 2-6-2, are: