8O ROUGH-AND-TUMBLE EN<iI N KKKING 



ables the engine to pass the center without a jar. Too 

 much lead is a source of weakness to an engine, as it al- 

 lows the steam to enter the cylinder too soon and forms a 

 back pressure and tends to prevent the engine from ] 

 ing the center. It will, therefore, make your engine 

 bump, and make it very difficult to hold the packii. 

 the stuffing box. 



Insufficient lead will not allow enough steam to enter 

 the cylinder ahead of piston to afford cushion enough to 

 stop the inertia, and the result will he that your L-n^ine 

 will pound on the wrist pin. You most likely have con- 

 cluded by this time that "lead" is no small factor in the 

 smooth running of an engine, and you, as a matter of 

 course, will want to know how you are to obtain the 

 proper lead. Well, don't worry yourself. Your engine is 

 not going to have too much lead today and not en 

 tomorrow. If your engine was properly set up in the 

 first place the lead will be all right, and continue to be 

 right as long as the valve is not disturbed from its or: 

 position. This brings us to the most important duty of 

 an engineer as far as the engine is concerned, viz. : Set- 

 ting the Valve. 



SETTING A VALVE 



The proper and accurate setting of a valve on a steam 

 engine is one of the most important duties that you will 

 have to perform, as it requires a nicety of calculation and 



