8<> ROUGH-AND-TUMBLE ENGINEER 



times and you may find the eccentrics in their proper 

 place. Then you must go into the steam chest for the 

 trouble. The valves in different engines are fastened on 

 the valve rod in different ways. Some are held in place 

 by jamb nuts, and a nut may have worked loose, causing 

 lost motion on the valve. This will make your engine 

 work badly. Other engines hold their valve by a clamp 

 and pin. This pin may work out, and when it does, your 

 engine will stop, very quickly too. 



If you thoroughly understand the working of the 

 steam, you can readily detect any defect in your cylinder 

 or steam chest, by the use of your cylinder cocks. Sup- 

 pose we try them once. Turn your engine on the for- 

 ward center, now open the cocks and give the engine the 

 steam pressure. If the steam blows out at the forward 

 cock we know that we have sufficient lead. Now turn 

 back to the back center, and give it steam again; if it 

 blows out the same at this cock, we can conclude that 

 our valve is in its proper position. Now reverse the en- 

 gine and do the same thing; if the cocks act the same, 

 we know we are right. Suppose the steam blows out of 

 one cock all right and when we bring the engine to the 

 other center no steam escapes from this cock, then we 

 know that something is wrong with the valve, and if the 

 eccentrics are in their proper position the trouble must be 

 in the steam chest. If we open it tip we will find the 

 valve has become loosened on the rod. Again suppose we 



