« НазадПродовжити »
FIG. 20.-Decapod Switching Locomotive with Walschaert Valve Gear. Built by the American
Locomotive Co. The heaviest and most powerful switching engine.
Valves, piston type, internal admission. Diameter of driving wheels, outside, 52 inches. Total heating surface, 4,6 25.4
Grate area, 55 square feet. Working pressure per square inch, 210 pounds. Tender capacity, water, 8,000 gallons. Tender capacity, fuel, 12 tons.
Maximum tractive power, 55,362 pounds.
same locomotive company, is shown in Fig. 20, and also is equipped with Walschaert's motion.
In all of the illustrations of Walschaert's valve gear so far shown, as applied to American locomotives, it will have been noticed that the link is invariably suspended from a bracket that is attached to the guideyoke, and the valve-stem slide is also carried by the guides, this to insure permanency in the alignment of the gear; but with certain types of large freight engines it is sometimes inconvenient so to place the link bracket, and the American Locomotive Company have built quite a number of engines that have a very large casting extending across, under the boiler, that is really a strong cross-brace to the engine frame at the point where such a brace is most needed an impossibility with the common link motion and this casting is used to carry the link and reversing shaft. Some engines have this brace unattached to the guides, however, while with others it is attached rigidly to the guide-yoke, the latter type being represented in Figs. 200 and 206, which are reproduced from the American Engineer and Railroad Journal and that journal gives the following description:
The illustrations show this new design so clearly that it needs but little explanation, and by reference to them it will be seen that the support for the small crosshead connecting to the valve-stem has been
placed on an entirely separate guide, which is fastened to the back valve chamber head and through an expansion link to the guide yoke instead of having it supported directly from the main guide, as in previous designs. The bearings for the reverse shaft and the link have been placed near together in the same casting and the radius rod of the valve gear is operated through a hanger from the arm of the reverse shaft instead of a sliding joint, as was used before when the reverse shaft was supported in a bearing on the frame between the second and third pair of drivers (as in Fig. 11). The link itself has been made somewhat larger and more bearing surface given to the block. The casting forming these bearings is fastened to a massive but not excessively heavy steel casting extending across the frame. The construction of this casting and its dimensions are clearly shown in the illustration. To this is also fastened the yoke supporting the main guides. Another change is also noticed in that the arm from the reverse shaft, to which is connected the reach rod, extends downward instead of upward. This necessitates the reach" rod being placed outside the driving wheels and on an incline from the reverse lever. It is supported and steadied by a guide at the throat sheet. A change has also been made in the return-crank connection at the main-pin for the purpose of permitting it to be more quickly and easily removed,