42 SCIENCE OF SUCCESSFUL THRESHING. 



Turn the engine so that the cross-head pin comes opposite 

 the hole in the engine frame nearest the crank. Take off 

 the washer on the crank pin and remove the grease cup and 

 the nut from the cross-head pin. Drive the cross-head pin 

 out with a wood block, turn the engine on rear dead center, 

 and the connecting-rod may be lifted off. Set the wedges 

 down as far as they will go, and take out the adjusting bolts. 



FIG. II. THE CONNECTING-ROD. 



The wedge and half of the box next to it may be driven out 

 from the inner side with a wood block. Before taking off 

 the connecting-rod, make a scratch across the wedges and 

 the rod end, so that in putting them back the wedge may be 

 set in the same position as before. 



As the .pressure is nearly all endwise on the rod, the holes 

 in the brasses will tend to wear in an oval shape, so that 

 when the boxes are tightened, they will bind at the top and 

 bottom, causing them to heat, while they still pound endwise. 

 To obviate this difficulty, the boxes should be "relieved" at 

 the top and the bottom by filing with a half-round file. They 

 should not touch the pin for a distance of one-half to three- 

 quarters of an inch each side of the joint. In time, the 

 brasses will have worn so much that the wedge strikes against 



