12 SCIENCE OF SUCCESSFUL THRESHING 



the water in the boiler is sufficient for only a few minutes 

 and the pump or injector must be started before the water 

 gets low in the boiler. 



The steam pressure should now be raised to the blow- 

 ing-off point (say 130, 140, or 160 pounds), to try the 

 pop or safety valve. If it does not open at this pressure, 

 pulling the lever will probably start it. If not, it is out of 

 adjustment and should be re-set, as explained elsewhere 

 in this book. 



Starting the Traction Parts. When the engine has 

 been run a sufficient time to insure everything being in good 

 running order (if it be a traction engine), preparations 

 may be made for a trip on the road. To do this, the trun- 

 nion-ring of the friction-clutch should be oiled and the 

 shoes adjusted to properly engage the rim of the fly-wheel. 

 Any paint that may be on the long hub of the arm should 

 be scraped off to allow the free movement of the ring, which 

 slides thereon, as the clutch is thrown in or out of engage- 

 ment. All the traction gearing should now be lubricated, 

 and a quantity of oil poured into the cannon-bearings. 

 Next the stud of the intermediate gear, the bevel pinions 

 of the differential gear, and the bearings of the steering- 

 roller and hand-wheel shaft should be oiled. The steer- 

 ing-chains should be properly adjusted as elsewhere ex- 

 plained. 



Caution. A new engine should have close attention for 

 the first few days until the bearings become smooth. The 



