PLOWS FOR MECHANICAL POWER 173 



A solid wooden platform, usually laid on in sections, covers 

 the frame and affords ample room for the operator, a toolbox 

 and miscellaneous supplies. Usually it extends far enough 

 forward so one may step to it from the engine. 



The carrying wheels are about 25 inches in diameter, with 

 tires from 6 to 8 inches wide. In some types three wheels are 

 used, one near each point of the triangle. On others four are 

 used, two on either side. In this case one wheel on the right 

 side follows the frame. The objection already mentioned as to 

 four points of contact is perhaps less forcible in a flexible hitch 

 plow, but in uneven ground the running of the plows is affected 

 nevertheless. One three-wheeled type has a wheel at the 

 rear corner, one on the right side behind the oblique tie bar, 

 and one in the centre in front, thus practically reversing the 

 usual triangle. The front wheels on nearly all types are 

 castered to facilitate turning, and in one case all four are 

 pivoted. One plow has two caster- wheels on the left-hand 

 side, connected with a steering lever. By this means the plow 

 can be turned in less radius than the engine and backed into 

 any desired position with the help of a stiff pushbar. For 

 breaking in rough ground long skids are sometimes used advan- 

 tageously in place of wheels as they cause the frame to run 

 more nearly level. 



The shares and moldboards vary according to the spil in 

 which they are to be used, but depart little or none at all from 

 horse-plow shapes. This accounts largely for the adoption 

 of a low speed of travel j>n plowing tractors. The beams are 

 longer than on horse plows, in order to give the clearance neces- 

 sary in trashy ground. One type, especially constructed as a 

 general purpose plow, combines a long beam, a high standard, 

 and no landside, minimizing the danger of choking. For 

 breaking sod the beam might be set quite low without difficulty 

 from choking, but this interferes with the use of a rolling coulter. 

 For stubble plowing and "backsetting" (turning back a layer 

 of sod with an extra inch or so of dirt on top of it) the high 



