8O SCIENCE OF SUCCESSFUL THRESHING. 



"Case'' engines built since 1898 the main shaft is counter- 

 sunk for the set screws. 



Even Cut-offs. The above is the method used in setting 

 the valve on nine, twelve, fifteen, twenty and twenty-five 

 horse-power "Case" traction engines at the factory, and brake 

 and indicator tests show that these engines, with their valves 

 so set, easily develop three times their rated horse-power, and 

 are very economical. It will be seen that this method of set- 

 ting 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, alike on both ends, for both road and 

 threshing-motions. 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 manner 

 as that of a simple engine, the part of valve covering low- 

 pressure ports only, being considered. 



Setting a Valve with Link Reverse. After having taken 

 up all the lost motion, as explained, the first thing to do, in 

 setting the valve on an engine equipped with the "link" re- 

 verse, is to find the correct length of the eccentric-rods. To 

 do this, take off the steam-chest cover and place the reverse 



