any one cause. It may be a combination of two, three,
or more of the conditions mentioned in the second para-
graph. The operator must act in cases of scouring
troubles very much like a physician diagnosing compli-
cations in a case of illness, and then apply the proper
remedies for each trouble.
148 THE OLIVER PLOW BOOK
Enough has been said to show that a dull, or incor-
rectly shaped share can do irreparable damage, and the
operator never discover the source of the trouble unless
he takes time to investigate.
Incorrect hitching and a dull share combined cause a
plow to do so many erratic things that the share symptom
is often overlooked in seeking to rectify the trouble by
hitch adjustments alone.
Setting the Share on the Plow
KNOWING how to drive the team properly and
make the hitch correctly are two points that deter-
mine good plowmanship. The other one is to know that
your plow bottom is in the right condition. The share is
the vital part in this work. If the operator is positive the
share has the correct shape for land suck and penetration,
he has little to worry about in making the plow work
successfully. A plow bottom operating correctly cuts
all the furrows the same width, the same depth, and
runs level. If the plow is not doing this naturally, some-
thing is wrong. The first thing to investigate is the
If the bottom has a tendency to rise when the hitch
is made where it always has been in the past for plow-
ing that depth, the plow share is worn rounding on the
under side, giving the share a sled runner effect. The
tendency is to work out of the ground instead of into it.
Sharpening the point is necessary to rectify this trouble.
If the furrow bottom is uneven and full of gouged
places, the plow bottom is running on its point. If the
hitch is the same as it has been in the past for plowing
at this depth, the trouble is that the point of the share
is bent downward too much, causing it to move forward
with a jumping motion. This can only be rectified by
putting a gradual slope on the point.
THE OLIVER PLOW BOOK
In shafting the point of a plow share the greatest care should be ex-
ercised to see that it has a gradual wedged shaped slant. One of the
difficulties encountered when carelessly sharpening shares is to put the
point of the share oser the edge of the anvil, then hit it a blow with a
hammer. The result is worse than the equivalent of a dull share.
Instead of the ploio going in deeper as intended, it gouges along the
ground and increases the draft of the plow. The illustration shows
the proper angle and shaping of the point.
The wing of the share when properly sharpened, rests on a straight
edge with the point. The edge of the throat is slightly raised from the
straight edge. This means that when the plow is operating in the ground
the point is as much low as the throat is high on the straight edge.
SETTING THE SHARE ON THE PLOW
152 THE OLIVER PLOW BOOK
If the plow bottom has a tendency to pull down on
the point so as to bear heavily on the land wheel and
lightly on the furrow wheels, the share is bent upward
too much on the wing. To remedy this the wing of the
share must be lowered.
If the plow has a tendency to bear down heavily on the
furrow wheels and not on the land wheel, there is too
much dip or suck in the wing of the share. This must
be rectified by raising the cutting edge of the wing.
The length of time that the bearings and axles of
wheel plows wear, providing they are kept properly
greased, is largely determined by the correct adjust-
ment of the plow bottom. For this reason, as well as
that of good plowing, plow shares should be kept sharp
and adjusted correctly.
These are delicate operations and a competent smith
or plowman should be consulted if the operator is not
absolutely certain which course to pursue.
The share of a walking plow has more wing than the
riding plow. This additional wing surface is necessary
as a bearing to keep the plow running level. On sulky
plows the wheels carry this weight. Hence, when the
shares of wheel plows are properly sharpened, only the
cutting edge comes in contact with the ground. The
effect of the wrong set on a share is immediately notice-
able in a walking plow and is identical with that of the
wheel plows. The operator has to stand the brunt of
the incorrect adjustment that the wheels and frame of
wheel plows sustain.
When one remembers that the point of the share
extends a slight distance landward from a line parallel
with the landside to make it hold the land, and slightly
downward below a line parallel with the bottom of the
SETTING THE SHARE ON THE PLOW 153
andslide to hold it in the ground, and the wing of the
share with edge shaped to keep the bottom working
level, he will have little difficulty in setting a share on
the plow bottom.
Shares and bottoms made by different manufacturers
have differences in shapes, but the general principle is
Sharpening Soft Center
r*HE majority of steel shares are made of soft center
1 steel, a term applied to the use of a layer of low carbon
steel between two of high carbon. The soft center steel is
by far the most common steel share in use and requires a
particular treatment in sharpening because of the peculi-
arity of wear upon it. Most of the wear on the share takes
place on the underside, hence the lower layer of high
carbon steel wears away faster than the upper one. This
must be observed very carefully in sharpening the share.
In heating, care should be taken that only the portion
of the share which is to be pounded out is heated. This
can be done by laying the share flat with the edge
over the center of the fire and filling up the underside
with green coals. This keeps the greater part of the
share cool, thus preserving its shape. The common
mistake is to put the share in the fire in a vertical posi-
tion with the edge down. This heats too much of the
share and causes it to warp and spring out of shape.
The pounding should be done from the upper side with
the bottom of the share flat on the anvil. This keeps
the cutting edge down and works the hard steel of the
upper surface over the soft steel in the center, thus pre-
serving for the share a hard cutting edge. Since shares
receive the most wear on the under side, pounding the
share on this side exposes the soft center steel and
has a tendency to work the cutting edge out of shape.
THE OLIVER PLOW BOOK
A picture of a soft center steel share pounded on the upper side. The
edge has the appearance of being somewhat rough but the hard steel was
worked down over the edge. Sometimes in heating soft center steel
shares the layers of steel are loosened. Wherever this happens pounding
the share on the upper side keeps it from wearing away.
Soft center steel share pounded on the under side when being sharpened.
Notice that the hard steel on the surface has been broken away on the
edge and on the point. This is caused by improper heating when
sharpening and pounding the share on the under side. A little practice
in sharpening soft center steel shares in the correct way and an under-
standing of how to set them on the plow will eliminate a great deal of the
difficulty farmers experience in the operation of the plow.
After the point has been hammered on the anvil
to the proper shape, if necessary, a piece of steel can
be welded to the top of the point.
Care should be taken in doing this work not to dent
the share when hammering it out as this would spoil
its scouring qualities.
SHARPENING SOFT CENTER STEEL SHARES 157
To temper the share properly after it has been ham-
mered out requires uniform heat. The right heat is a
dull cherry red, a temperature of approximately 1 472 F.
One of the most successful methods of tempering is to
slowly draw the share through the fire with the cutting
edge down until the edge has been heated to the proper
color. Then draw the share from the fire, put the point
far enough into the ground to hold up the share, and let
it stay there until it cools.
Sharpening Crucible Steel Shares
/CRUCIBLE steel shares are made of one piece of steel.
^^ They cannot be tempered so hard as soft center
steel because tempering makes them too brittle and
thus subject to easy breakage.
Ground that sheds easily can be successfully plowed
with a crucible share.
Crucible steel shares can be sharpened exactly the
same as soft center steel shares, or they can be treated
according to the old custom of pounding the share on
the reverse side. However, there is less danger of
misshaping the edge of the share if it is pounded on
the upper side.
Sharpening Chilled Shares
/^HILLED shares are made in moulds the same as
^^ chilled mouldboards. On account of the nature of
the iron they cannot be heated and drawn out by pound-
ing as can steel shares. When it becomes necessary to
sharpen chilled shares they must be ground on the
upper side on an emery wheel or grindstone until a
bevel edge appears.
The Rolling Coulter
' I 'HE purpose of the rolling coulter is to cut the stubble
and trash into lengths the width of the furrow and
leave a smooth furrow bank. On account of the great
difference in soil texture and the varieties of trash dif-
ferent adjustments are necessary to bring about this
To make the furrow bank smooth the rolling coulter
must be set to the land far enough away from the plow
shin and deep enough in the ground to prevent the shin
of the plow from digging into the furrow bank made by
the rolling coulter. In ordinary conditions the coulter
set to cut a furrow J4" to Y% wider than the plow bot-
tom will suffice, but by no means can anyone assume that
this is a set rule to follow. Set the coulter so that it
accomplishes the result intended.
One must remember when setting a coulter to properly
cut the furrow bank that, if the coulter, when set, is not
running parallel with the landside of the plow, the plow
is out of adjustment and the bottom must be correctly
adjusted before the rolling coulter can be finally set.
The depth at which the rolling coulter operates must be
determined solely by conditions.
In cutting trash the coulter should make with the
surface of the ground a condition similar to a shear cut,
using the ground for one edge of the shear. In order to
produce this shear cut with the rolling coulter it is
necessary to have the coulter high enough to force
THE ROLLING COULTER
This illustration shows the effect of a plow out of adjustment on the
rolling coulter. The rolling coulter is always pulled in a straight line
of draft. The bottom as is illustrated by the landside shows that it is
wording out of its true line of draft. The clods and earth on the edge of
the furrow bank are telltale evidences of the wrong plow adjustment.
162 THE OLIVER PLOW BOOK
the trash down and under. The coulter cannot
do this if it is set deep enough in the ground for
the downward motion at the cutting edge to be prac-
tically straight. For this reason the safest rule is to set
the coulter deep enough to cut the trash without clogging
and shallow enough to cut the trash without riding over
part of it.
When operating the plow in hard ground the coulter
set high and as far back as possible gives the plow point
a chance to penetrate the ground first. The plow
bottom sucks its way into the ground. The rolling
coulter must be forced into the ground. If the coulter
is placed ahead of the plow point part of the suction of
the bottom will be utilized in pulling the coulter into the
ground. If the plow point penetrates first it has the
advantage of the weight caused by deeper penetration
to hold the coulter in the ground.
In plowing stony ground the coulter set well ahead of
the point and very low prevents stones from lodging
between the coulter blade and the plow bottom.
A little study of these fundamentals will soon point
the way for properly adjusting the coulter.
The purpose of the jointer is to turn a small furrow on
top the furrow slice so that when this slice is inverted
the trash, stubble, sod, etc., may be turned to the
bottom of the furrow.
The adjustment of the jointer is very much simpler
than that of the coulter. It should be set so that the
furrow it turns should rest upon the larger furrow slice
THE ROLLING COULTER
When the coulter is properly set the furrow wall is smooth with little
or no dirt on the unplowed ground next to the furrow wall. The clean
cut furrow slices and the absence of protruding stubble are the benefits
of a correctly set combined rolling coulter and jointer.
THE OLIVER PLOW BOOK
Observe the jointer turning a little furrow into the right-hand corner
of the big furrow bottom. This is necessary for ideal plowing.
THE ROLLING COULTER
in such a way that it will roll into the lower right hand
corner of the furrow when the slice is being inverted.
For the most part this point is slightly ahead of the
point of the plow and on the unplowed land J4" to M"
from the shin of the plow. These measurements are by
means fixed. The adjustment must be made to
bring about the desired results.
The jointer cannot be used by itself in very trashy
ground because the trash will catch on the point of the
shin and clog the throat of the plow. This fact led to
the use of the combined rolling coulter and jointer, the
adjustment of which is practically the same as that of
the rolling coulter and jointer separately.
The Combined Rolling Coulter
The combined rolling coulter and jointer is a recent
improvement in plows and has made possible the suc-
cessful covering of weeds and trash in the lower right
The combined rolling coulter and jointer is one of the greatest helps for
166 THE OLIVER PLOW BOOK
hand corner of the furrow where they interfere very little
with the upward trend of moisture and thus rapidly
help make humus out of the weeds.
The combined rolling coulter and jointer is the only
attachment that has been invented for use with plows
which absolutely assures that all kinds and sizes of trash
will be buried deep enough in the ground for the suc-
cessful eradication of insects which plowing puts out
of business. Whatever time of the year it may be neces-
sary for plowing it is always advisable to have that plow
equipped with a combined rolling coulter and jointer
and to see that all trash is buried on the bottom of the
The Tractor Plow Hitch
BEFORE one attempts to adjust a plow he should know
the physical laws that govern the operation of plows.
Otherwise he is groping in the dark. It has been the
experience of a great many plow experts that the prin-
ciples or physical laws underlying the working of plows
are not generally understood. For this reason this
chapter will treat plow adjustments from the theoretical
side (which after all controls the practical), rather than
enter into a discussion of how the operator should change
the hitch to produce certain results. Another reason for
treating the matter from the physical law side is that
specific instructions sometimes produce the opposite
from the intended results. This happens quite often
when instruction books are followed. No writer of
instructions can call before his mind all the different
conditions that must be met; consequently the best
intentions cause trouble by the reader's inability to
diagnose conditions correctly.
The draft laws that control the operation of tractor
plows are the same for wheel and walking plows. How-
ever, different adjustments are necessary to make these
different types of plows conform to the basic law govern-
ing proper adjustments. This law stated very specifi-
cally is: The shortest distance between two points is a
straight line. In tractor plow adjustments one of these
points is the "center of power" of the tractor, usually
regarded as a point on the rear axle at equal distance
THE OLIVER PLOW BOOK
from the drivers. The other point is the "center of
draft" (also called the center of weight or the center of
resistance) of the plow. A straight line between these
points is the "line of draft." The line between these
two points is theoretically always straight.
Being obliged to turn the front tractor wheels toward the plowed ground
indicates that the draft of the plow is pulling the front of the tractor in
the opposite direction. This is hard on both the plow and the tractor.
The center of draft of the plow is an imaginary point
in the plow base or bottom from which a single force
pulling straight ahead and parallel to the furrow wall
will cause the plow to work correctly with the minimum
effort. This point is usually placed from 12 to 15
inches back from the share point, 2 inches up from the
furrow sole and 3 inches from the furrow wall. One
must remember that this point is not fixed but con-
THE TRACTOR PLOW HITCH
stantly moves from side to side and up and down on
account of the variations in shapes and the intensity
of the pressure of the earth against the bottom. But
for the sake of explaining the principle we will assume
that this point is correct. In actual practice a slight
variation does not materially affect the working of the
Being obliged to turn the tractor in this direction shows that the draft
of the plow has a tendency to pull the wheels toward the plowed ground.
This puts enormous end-thrust on the front of the tractor, and demands
additional power for operation.
It is impossible to pull a plow in the true line of draft
because the hitch would be below the surface of the
The fact that the power cannot be operated in a line
parallel with the landside through the center of draft of
the plow necessitates two lines of draft. These two
170 THE OLIVER PLOW BOOK
lines one a vertical line of draft (or force) tending to
pull the plow out of the ground and the other, the line of
side draft, which has to do with keeping the plow oper-
ating straight ahead determine plow adjustments.
The line through which these forces neutralize (or the
resultant force) is the true line of draft from a practical
standpoint. All plow adjustments must be made to
keep this line straight, because this line will straighten
theoretically regardless of how the plow or the tractor
When we understand these laws and what is necessary
to keep the line between these two points straight, that
is, between the center of power and the center of draft,
we can readily see why it is necessary to have the plow
beams and a vertical adjustment to take care of the
penetration of the plow, as well as a horizontal adjust-
ment to take care of the side draft.
In Fig. 5 is illustrated the vertical line of draft. C is
the center of draft of weight. CX is the theoretical line
of draft. B represents the center of power of the
tractor. BGC then represent the line of draft passing
through the clevis on the front of the beam of the plow
at G. If the line BGC were angled as BHC and the
resistance at point C required more power than the
force necessary to straighten the line, it is evident that
the line BHC would assume the position BGC before
the plow would move. Hence the bottom would rise
until BHC reached the position BGC.
Obviously this would lessen the depth of the plow
regardless of the fact that there may be a wheel at the
rear and one at the front. If the front wheel happened
to be the controlling factor of a power lift, the lift would
refuse to work because of the lack of weight to hold the
THE TRACTOR PLOW HITCH
1 72 THE OLIVER PLOW BOOK
wheel on the ground. However, it is easy to imagine a
hard plowing condition where the plow depth would
remain the same and the effect show on the tractor.
But remember that whatever happens to the plow or
tractor, the draft line straightens.
Suppose the plow at point, C, requires 550 pounds
effort to move ahead, and the tractor can only produce
525 pounds effort. In this case the plow would remain
stationary and point, B, the center of power of the
tractor, would lower until it reached the line AHC,
providing no outside influence stopped it. If point, B,
were back of the center of power the front wheels of the
tractor would rise. If point, B, were ahead of the
center of power undue weight would be brought to bear
on the front trucks, and the rear wheels of the tractor
would tend to slip because of the tendency to relieve
them of weight. When this condition occurs, as it often
does, the operator must adjust the hitch on both the
plow and tractor until the draft line is straight.
It is further apparent that the height of the hitch on
the tractor and the range of clevis adjustment on the
front of the plow have everything to do with keeping
this line straight when plowing at different depths.
Theoretically speaking, a different adjustment should
be made on a vertical clevis every time the plow depth
is to be changed, but from the way plows are designed, a
slight variation in depth can be made without materially
affecting the draft line. However, one should be very
careful when adjusting the plow depth to vary it as
little as possible if he expects his plow to operate per-
Another feature of the vertical adjustment is shown in
Fig. 5. The lines, AHC and BGC, show that the different
THE TRACTOR PLOW HITCH 173
distances between the plow and the tractor necessitate
different adjustments to plow the same depth. In
other words, the farther the tractor is removed from the
plow, the lower it is necessary to hitch in the vertical
clevis if the operator desires to plow at the same depth
as when the tractor is hitched to the plow at point B.
When the hitch on the tractor is exceedingly high it
may become necessary to lengthen the hitch between the
plow and the tractor to make the plow run at the depth
the operator desires. This is another way of saying,
keep the draft line straight.
The reader will permit a diversion at this point long
enough to say that there is no truth in the theory that a
short hitch makes possible lighter draft than a long
hitch. The reason for this is very plain when we once
understand that the minimum amount of draft required
to pull a plow must be through a straight line from the
center of draft or center of weight to the center of power.
As long as the tractor and plow are in this relation the
only difference is the weight of the additional length ot
the draft bar.
It is further apparent from Fig. 5, that if the hitch
line is BKC and the force on the plow bottom is sufficient
to draw line BKC into BGC, more power will be re-
quired to pull the plow because the front wheel will have
to sustain the brunt of the downward pressure. This
naturally will cause the plow to run on its point, mak-
ing an uneven furrow bottom and interfering very
materially with the pulverizing of the ground by the
mouldboard. This is apt to throw the ground over
into clods, breaking them rather than pulverizing.
174 THE OLIVER PLOW BOOK
If the plow has no front wheel, it is equally obvious that
the bottom will go deeper in order to straighten the
If a wheel plow is working in ground that is hard to
plow this trouble may not be noticed, but the instant it
strikes easy ground the trouble will become plain im-
Another way for the operator to determine whether
or not this point of draft is correct is to raise the front
furrow wheel and also the landside wheel if they are
both well to the front of the plow. The plow will im-
mediately begin to penetrate deeper and deeper if the
line of draft is not straight at the depth desired to plow.
If the plow is a gang, this condition will cause the
front bottom to penetrate deeper than the rear bottoms.
This naturally then requires lowering the hitch at K to
the point G on the vertical clevis.
Side draft would not take place if the line of draft
could be operated parallel to the furrow wall. The
principle back of adjusting the side pull is identically the
same as that of adjusting the vertical pull with the
exception that it operates in a horizontal plane. If this
be true, the question of why cannot this line of draft be
operated at an angle as successfully as the vertical draft
at once arises. The answer lies in the construction of
the bottom. The suck and wing of the share are made