104 MACHINE, SHOP, AND DRAFT PROBLEMS 



6. A team is hitched to a doubletree 4 ft. long. At what 

 point must the doubletree be attached to a load so that one 

 horse will pull 1^ times as much as the other ? 



DOUBLETREE EVENER 



7 . When the draft is 6 Ib. per square inch of cross section 

 of the furrow, estimate the draft of a 12-inch plow running 

 6 in. deep ; of a 14-inch plow running 6 in. deep. 



NOTE. In general, the horse is able to exert a pull equal to ^ 

 or J of his weight. A plow will generally require a pull, or draft, 

 of from 4 to 8 Ib. per square inch of cross section of the furrow. 



8. How many square inches are there in the cross section 

 of a furrow 12 in. wide and 4 in. deep ? What pull does a 

 team exert in plowing if the draft is 5 Ib. per square inch ? 



CROSS SECTION OF A FURROW 



9. A team weighing 2500 Ib. is to be used in plowing a 

 field 5 in. deep. If the team exerts a pull of of its weight, 

 and the draft is 4 Ib. per square inch of cross section of the 

 furrow, should a 12-inch or a 14-inch plow be used ? 



