IO2 SCIENCE OF SUCCESSFUL THRESHING 



engines, with their valves so set, easily develop their 

 rated horse-power, and are very economical. It will 

 be seen that this method of setting the valve gives unequal 

 "leads" for the threshing-motion, there being three-thirty- 

 seconds of an inch on the crank-end and no lead on the 

 head-end. The points of cut-off, however, will be "even," 

 that is, substantially alike on both ends, for both road and 

 threshing-motions. 



Equal Leads. Were it desirable to set the valve with 

 equal "leads," it could be done by making the pedestal of 

 such a height that there would be no "slip." In this case, 

 the points of cut-off would not be even, and one end of the 

 cylinder would do more work than the other. For this, 

 and other reasons, this method is not recommended. 



Setting the Valve on Compounds. The valve of the 

 Woolf-compound cylinder is set in exactly the same man- 

 ner as that of a simple engine, the part of valve covering 

 low-pressure ports only, being considered. 



How to Set Valve on Portable Engines. See that 

 there is no lost motion in the connecting-rod brasses, 

 main bearings and the valve-rod connections, the latter 

 being most important. Remove steam-chest cover. Now, 

 with the eccentric secured to the crank-shaft, slowly turn 

 the fly-wheel in order to see that the valve travels an 

 equal amount on each side of the ports. This may be 

 conveniently determined by making fine scratches on the 

 valve seat along the edges of the valve when in its ex- 



