54 SCIENCE OF SUCCESSFUL THRESHING 



rocker-arms are taken up by driving down the wedges or 

 keys. 



The Main Bearings are adjusted by removing paper 

 liners. Take out only a little at a time. If one of the 

 bearings heats and does not cool when the nuts are loos- 

 ened, remove the cap and clean out any grit or dirt that 

 may be found. If the babbitt be rough and torn up, it 

 should be scraped smooth. It is well to "relieve" the main 

 bearings a little at their edges, as explained for the con- 

 necting-rod brasses. When paper liners have all been re- 

 moved, and the shaft has lost motion, the boxes will require 

 re-babbitting. 



Babbitting Main Frame Bearing. No one but a good 

 mechanic skilled in this work should undertake to babbitt 

 the main bearings. The difficulty lies in obtaining the 

 alignment, which must be perfect, before the babbitt is 

 poured. The babbitt should be of the best quality. 



First, remove the cylinder-head, piston and piston-rod, 

 connecting-rod and cross-head. Run a line (a fine wire is 

 best) through the piston-rod stuffing-box and fasten it by 

 any convenient means to a point in the rear of the crank- 

 disc and to a point in front of the cylinder. In the latter 

 case, a piece of wood may be bolted to the cylinder by one 

 of the stud-bolts which hold the cylinder head in place. 

 With a pair of inside calipers, the distance from the line 

 should be carefully measured at both ends of the cylinder, 

 at the stuffing-box and at the guides to insure its being 

 exactly central with the cylinder in all directions. Meas- 



