Rough and Tumble Engineering by James H. Maggard
page 60 of 122 (49%)
page 60 of 122 (49%)
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You are now ready to proceed with the setting of your valve, and as you
have both dead centers to work from you ought to be able to do it, as you do not have to depend on your eye to find them, and by the use of the tram You turn your engine to exactly the same point every time you wish to get a center. Now remove the cap on steam chest, bring your engine to a dead center and give your valve the necessary amount of lead on the steam end. Now, we have already stated that we could not give you the proper amount of lead for an engine. It is presumed that the maker of your engine knew the amount best adapted to this engine, and you can ascertain his idea of this by first allowing, we will say, about 1/16 of an inch. Now bring your engine to the other center, and if the lead at the other end is less than 1/16, then you must conclude that he intended to allow less than 1/16, but should it show more than this, then it is evident that he intended more than I/I16 lead; but in either case you must adjust your valve so as to divide the space, in order to secure the same lead when on either center. In the absence of any better tool to ascertain if the lead is the same, make a tapering wooden wedge of soft wood, turn the engine to a center and force the wedge in the opening made by the valve hard enough to mark the wood; then turn to the next center, and if the wedge enters the same distance, you are correct; if not, adjust till it does, and when you have it set at the proper place you had best mark it by taking a sharp cold chisel and place it so that it will cut into the hub of eccentric and in the shaft; then hit it a smart blow with a hammer. This should be done after you have set the set screws in eccentric down solid on the shaft. Then, at any time should your eccentric slip, you have only to bring it back to the chisel mark and fasten it, and you are ready to go ahead again. |
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