14 FARM MACHINERY 



ened more than the lever arm of the other horse. The 

 author's attention has been called to a wagon doubletree 

 in which the center and end holes for clevis pins are made 

 by iron clips riveted to the front and back sides of the 

 wood. The center hole was thus placed 4^4 inches out 

 of the line of the end holes. This evener is shown in out- 

 line in Fig. 2. 



By calculation it was found that if one horse was 8 

 inches in the advance of the other, the rear horse would 

 pull 8.64 per cent more than the first, or 4.32 per cent more 

 of the total load. If this difference was 16 inches, the 

 rear horse would pull 19 per cent more than the first, or 

 8 per cent more of the total load. 



26. Eveners. When several horses are hitched to a 

 machine as one team, a system of levers is used to divide 

 the load proportionately. The law of mechanics applies 

 in all cases, noting that the lever arm is the perpendicular 

 distance between the direction of the force and the ful- 

 crum or pivot. In general, it may be said that there is 

 nothing to be gained by a complicated evener. If there 

 is a flexible connection and an equal division of the draft, 

 the simple evener is as good as the complicated or so- 

 called "patent" evener. The line of draft cannot be offset 

 without a force acting across it. This is accomplished 

 with a tongue truck, which seems to be the logical 

 method. 



Fig. 3 illustrates some good types of eveners. 



27. Giving one horse the advantage. It often occurs 

 in working young animals or horses of different weights 

 that it is desired to give one the advantage in the share 

 of work done. This is accomplished by making one 

 evener arm longer than the other, giving the horse 

 which is to have the advantage the longer arm. This 

 may be done by setting out his clevis, setting in the clevis 



