MOTIVE POWER 481 



draft pin, the proper distance for the singletree pin for 

 the lighter horse is determined as follows : 



2iXi5o = iooX* 



150X21 



x=— =31 . 5 



100 ° ° 



Therefore the pin of the singletree of the lighter horse should 

 be 31.5 inches from the draft pin. Then each animal will 

 pull his proper share of the load. (See Fig. 372.) 



Evener construction. In practice it is frequently neces- 

 sary to keep the animals an equal distance from the tongue. 

 This can be accomplished by means of shifting the evener 

 at the draft pin, making all or a part of the adjustment 

 there instead of making all of it at one end. In this way 

 the proportion between the length of the two evener arms 

 can be maintained. In the shifting of the draft pin a move- 

 ment of 1 inch is approximately equivalent to moving the 

 singletree pin 2 inches, since the singletree moves the pulling 

 point of only one horse, while the draft pin moves both. 



On a three-horse evener it is customary to hitch a team 

 to a two-horse evener and attach that to the three-horse 

 evener, having one horse attached to the long end with a 

 singletree. The team can be balanced against the single 

 horse if their combined weight is considered as that of one 

 horse and the proper length of the evener arms is then 

 computed as described for a two-horse evener. When the 

 three animals are of equal weight, the evener arm for the 

 single horse will be twice as long as the evener arm for 

 the team. Four- or five-horse eveners can be adjusted on 

 the same principle. 



Position of devise pinholes. Teams are not always 

 matched in respect to gait or energy, one animal frequently 

 having a tendency to travel ahead of the other. This 

 causes the evener to take an inclined position with reference 

 to the line of draft or tongue. Both animals will be pulling 

 a proper proportion of the load so long as the evener arms 

 remain at right angles to the tongue and the pinholes are 



