FARM MOTORS 335 



with the two end holes, then the load is divided evenly only 

 when the two horses pull evenly together. If one horse pulls 

 in advance of the other, the load is no longer evenly divided. 

 It is customary to place the end holes well toward the rear 

 edge of the evener, and the center hole well toward the front 

 edge. This placement of the holes adds materially to the 

 strength of wooden eveners. 



When the holes are much out of line and when the horses 

 do not pull evenly, there may be much difference in the efforts 

 of each. In Fig. 214, which shows a wagon doubletree as 



Fig. 214. A wagon doubletree illustrating the effect of not having the 

 holes for the clevis pins in a straight line. 



actually manufactured, the rear horse would be compelled 

 to pull 18.9 per cent more than the leading horse, with one 

 end of the doubletree 16 inches in advance of the rear end. 



Three-Horse Eveners. In order to divide a load among 

 three horses, it is necessary to introduce a second lever, or 

 some other device to take its place. A usual method of 

 arranging such an evener is shown in Fig. 217. This is a 

 combination evener, which in this instance does not space the 

 horses evenly but indicates the general arrangement of the 

 three-horse evener, or tripletree. The factory-made triple- 



