142 



FARM MECHANICS 



Axles should hang at right angles to the line of lift 

 so accurately as to cause the wheels to wear but lightly 

 on the ends of the hubs. Mistakes in adjustment show 

 in the necessity of keeping a supply of washers on hand 

 to replace the ones that quickly wear thin. 



Figure 138. Corn Cultivator. A one-row, riding-disk cultivator. 

 The ridges are smoothed by the spring" scrapers to leave an even 

 surface to prevent evaporation. 



In this respect a good deal depends on the sand-bands 

 at the ends of the hubs. Plow wheels are constantly 

 lifting gritty earth and dropping it on the hubs. There 

 is only one successful way to keep sand out of the jour- 

 nals and that is by having the hubs, or hub ferrules, 

 extend well beyond the bearings. Plow wheel hub ex- 

 tensions should reach two inches beyond the journal 

 both at the large end of the hub and at the nut or linch- 



