176 POWER AND THE PLOW 



and standard. A set screw at the fore end of the beam also 

 secures this suction, but at the same time lifts the heel of the 

 share and causes it to cut at less depth than the point. Set 

 screws are commonly used on the fore end of the beams to 

 secure parallel alignment and to level up the bottoms. One 

 recent design has a device by which the sole of the plow is 

 claimed to be kept level at all depths. 



The depth or gauge wheel is a vital point in the design 

 of the plow for efficiency. It acts as a fulcrum for the lifting 

 of the plow and carries the weight of one or two bottoms in 

 moving from place to place. It should be large, so that minor 

 irregularities of the surface will not be transmitted to the 

 furrow. This is particularly desirable in backsetting. At 

 the same time the wheel should be so attached as to allow deep 

 plowing in stubble. It should be located so as not to twist 

 the beam and cause one side of the furrow to be deeper than 

 the other. It should protect the point of the share. It should 

 not interfere with the rolling coulter, which by common con- 

 sent is placed just to the left of the shin of the plow, and just 

 high enough to clear the shin in swinging. It must not clog 

 up with trash and dirt. 



The kind and position of gauge wheel best complying with 

 these essentials is an open question. The solid cast wheel 

 without flanges is successful in avoiding trash. The castered 

 wheel is used on a few types, being kept in line by earth resis- 

 tance. Its greatest advantage lies in the fact that in turning 

 or on striking uneven surfaces it is free to swing and follow 

 without skidding. This relieves the twisting strain on the 

 beam caused by the fixed wheel when bearing heavily on one 

 edge of its rim. On the other hand, with both coulter and 

 depth wheel castered, interference is more likely. 



If the depth wheel is placed directly under a beam of ordi- 

 nary clearance, or between two closely connected bars of 

 a straight-beam plow, either it must be too small for general 

 work or it cannot be raised high enough for deep plowing. A 

 height of beam of from twenty to twenty-two and one half 



