PRINCIPLES OF MACHINES 475 



CHOICE AND CARE OF MACHINES 



Durability. The durability of a farm implement will 

 depend on the material of which it is made, the attention 

 given it while it is in operation, and the care taken of it when 

 it is not in use. In the selection of a farm implement due 

 consideration should be given to the local conditions where 

 it is to be used, to the nature of the crop grown, and often 

 to soil and moisture conditions. A study of the advantages 

 and disadvantages is desirable, especially if the machines 

 can be seen in operation under different conditions. Dealers 

 are usually interested in supplying a standard make of 

 implement that experience has proved to be suitable for 

 local requirements. A low first cost may not mean a cheap 

 machine, and one that is not standard will be expensive to 

 keep in repair. Extreme sizes are not advisable, for if the 

 machines are too small the 

 work is rendered slow, and 

 if too large they are sub j ect 

 to great strain and more 

 power is required to* oper- 

 ate them. There is usual- 

 ly an advantage in having . After lDfa ?? at ? n !j f a 7 ster c 7 °- . 



J ° . Fig. 369. A removable hub bushing, lock 



all equipment along the line nut, and hub cap for a cultivator wheel 

 r ... . which may be replaced when worn 



of medium requirements. 



Bearings and pinions are generally the parts subject to 

 greatest wear and should be replaced by new ones without 

 delay. The oil-saturated hardwood bearings have been 

 found satisfactory in many instances. The implement 

 which will efficiently perform the work and has the least 

 number of moving parts will be the most desirable. Nothing 

 is gained by an increase in the number of moving parts 

 unless better work or more work with the same power can 

 be accomplished. Tillage implements working in the fresh 

 soil are subjected to dirt and grit, and the boxing should be 

 specially protected to prevent their entrance into the bear- 

 ings, and provision should be made for replacing the boxing 



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