480 



ENGINEERING ON THE FARM 



the same load is to have each horse working at a rate which is 

 commensurate with his strength and ability and not require 

 him to pull more than his proportionate share of the load, 



in order to keep up with the 

 heavier or more capable 

 animals, for the efficiency 

 of the team is dependent 

 upon their united and not 

 their individual efforts. If 

 one gives out, the team 

 power is disorganized. 

 The pinholes in the evener 

 should be so adjusted that 

 when all of the horses are 

 pulling their proportionate 



<r—Line of 

 draft 



Fig. 371. When the pinholes are in a 



straight line, the length of the evener 



arm remains the same irrespective 



of the inclination of the evener 



with the line of draft. 



share the evener will remain exactly in line if the various 

 parts are free to move back and forth according to the pull 

 of the animals (Fig. 371). 



When one horse is pulling more than another, adjust- 

 ment can be made if the distance from the singletree pin 

 to the draft pin is made shorter for the heavier horse than 

 for the lighter. The proper 

 relation can be expressed as 

 follows: The pull of one 

 horse multiplied by the 

 length of his evener arm is 

 equal to the pull of the other 

 horse multiplied by the 

 length of his evener arm. 

 For example, if a 1,500- 

 pound horse is worked on 

 an evener with a 1,000- 

 pound horse and the con- 

 dition of the two animals is the same, one exerts a pull of 1 50 

 pounds as easily as the other a pull of 100 pounds. If the 

 singletree pin for the heavier horse is 21 inches from the 



f 



■Line of 

 cfraff 



Fig. 372. When the pinholes are not 



in a straight line and the evener is 



inclined to the line of draft, the 



evener arm which is farthest 



in advance will be longer. 



