All plows should have a leather pocket on the side of the beam to carry a file. A 12-inch bastard file with a good handle is the most satisfactory implement for sharpening the cutting edges of a plow in the fields. A good deal depends on the character of the soil and its condition of dryness, but generally speaking, it pays to do a little filing after plowing a half mile of furrow. If the horses are doing their duty, a little rest at the end of the half mile is well earned. The plowman can put in the time to advantage with the file and the next half mile will go along merrily in consequence. No farmer would continue to chop wood all day without whetting his axe, but, unfortunately, plowmen often work from morning till night without any attempt to keep the cutting edges of their plows in good working order.
Riding Plow.—The riding plow in lifting and turning the furrow slice depends a good deal on the wheels. The action of the plow is that of a wedge with the power pushing the point, the share and the moldboard between the furrow slices and the land side and the furrow bottom. There is the same friction between the moldboard and the furrow slice as in the case of the walking plow, but the wheels are intended to materially reduce the pressure on the furrow bottom and against the land side. Plow wheels are intended to relieve the draft in this respect because wheels roll much easier than the plow bottom can slide with the weight of the work on top. The track made in the bottom of the furrow with the walking plow shows plainly the heavy pressure of the furrow slice on the moldboard by the mark of the slip. To appreciate the weight the slip carries, an interesting experiment may be performed by loading the walking plow with weights sufficient to make the same kind of a mark when the plow is not turning a furrow.
One advantage in riding plows in addition to the relief of such a load is less packing of the furrow bottom. On certain soils when the moisture is just sufficient to make the subsoil sticky, a certain portion of the furrow bottom is cemented by plow pressure so that it becomes impervious to the passage of moisture either up or down. The track of a plow wheel is less injurious.
Figure 136.—Three-Section, Spike-Tooth Harrow. The harrow is made straight, but the hitch is placed over to one side to give each tooth a separate line of travel.
Figure 137.—Harrow Sled Long Enough to Hold a Four-Section Harrow.
Plow wheels should stand at the proper angle to the pressure with especial reference to the work performed. Wheels should be adjusted with an eye single to the conditions existing in the furrow. Some wheel plows apparently are especially built to run light like a wagon above ground regardless of the underground work required of them.