[AT] McCormick plow
charlie hill
charliehill at embarqmail.com
Thu Aug 21 15:57:27 PDT 2014
Agreed Dean and wheel slip has a lot to do with the left
brake getting a lot of use in addition to correcting the path
of the tractor. If you get everything set up just right though
a wide front tractor and plow will track perfectly. I've actually
seen the operator get off a tractor and let it plow by it's self for
a while. As far as the 3 point helping traction that's exactly
why Allis Chalmers called their system a "traction booster" and
it worked like a charm if it was right.
Charlie
-----Original Message-----
From: Dean VP
Sent: Thursday, August 21, 2014 4:42 PM
To: 'Antique tractor email discussion group'
Subject: Re: [AT] McCormick plow
Yep, there are a few more things we haven't taken into consideration include
what the wheels on a tag
plow contribute. Or what active load and depth control contributes on a
three point plow. Now if one
wants to get really technical each rear wheel slippage on the tractor has to
be taken into
consideration too. Usually the furrow wheel has a lot better traction than
the land wheel. And of
course add to all of that how well the front end holds the tractor straight.
On a trash heavy field
even if it has been disked well, rear wheel traction difference can be
really significant. A lot of
that is controlled though by how well the hitch has been set up. This is
where a 3 point plow with
load and depth control on the 3 point hitch really shines. Improves rear
wheel traction significantly
as the load gets heavier.
Dean VP
Snohomish, WA
They say necessity is the mother of invention.
Don't know who the father is, probably remorse.
Red Green
-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of
charlie hill
Sent: Thursday, August 21, 2014 1:23 PM
To: Antique tractor email discussion group
Subject: Re: [AT] McCormick plow
Yeah Dean I agree about the forces having to be equal. What you end up
solving for
is a vector or a simple line that could theoretically be substituted if
nothing was in the way.
I think as far as the side thrust goes the land slide pushing down against
the bottom of the furrow
and out against the unplowed side of the furrow reacts all of the side
forces caused by rolling the soil
over. I think that any of those forces that get applied to the drawbar are
caused by the plow not being
properly designed or adjusted. In theory all of the force should be applied
in tension in a line between
the hitch point on the drawbar and some center of rotation maybe somewhere
on the face of the plow.
Of course the forces absorbed by the land slide against the ground would
control where that center of
rotation or whatever is located. Does that make sense?
Charlie
-----Original Message-----
From: Dean VP
Sent: Thursday, August 21, 2014 1:36 PM
To: 'Antique tractor email discussion group'
Subject: Re: [AT] McCormick plow
Charlie,
All the forces have to come out equal. Really the static forces on the beam
come out equal (tension
and compression). The dynamic forces are the tractor moving force vectors
causing the soil to lift up
and roll over. What I am unable to get clear in my mind are the side forces
and how they become
linear with the pulling axis. Maybe the hitch on the tractor counteracts
that a bit and the landslide
in the furrow does as well. A fairly complex equation. I guess the hitch
has to try to rotate the
plow a bit to the plowed soil side and the resistance of the rolling soil
counter acts that force and
then stays straight. I've seen a force diagram for tag plows and even three
point plows somewhere in
an old JD book I think. First I have to figure out where to look and maybe
I might find it.
Dean VP
Snohomish, WA
They say necessity is the mother of invention.
Don't know who the father is, probably remorse.
Red Green
-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of
charlie hill
Sent: Wednesday, August 20, 2014 4:44 PM
To: Antique tractor email discussion group
Subject: Re: [AT] McCormick plow
I agree Dean. I can see the point of the person that wrote that.
I have no clue now where I read it.
I'm trying to think back and remember my statics and dynamics course
in college. There is a way to resolve the forces into one vector but I
don't remember
how. Maybe someone else does.
I guess the writer was looking at it from the point of view of the plow. If
you were the
plow and lets say that your nose was the plow point and the tongue was bent
around
and shoved up your rear, I suspect you'd think you were being pushed.
grins
Charlie
-----Original Message-----
From: Dean VP
Sent: Wednesday, August 20, 2014 6:35 PM
To: 'Antique tractor email discussion group'
Subject: Re: [AT] McCormick plow
Charlie,
Never quite thought of it that way before. Intelesting! However, I think
something has to pull the
pushing part though! :-) I guess I always think of pushing is when the
power to push is behind the
load. Another way to look at this is: The majority of the beam is pulling.
Then as the beam turns down
it starts pushing.
Dean VP
Snohomish, WA
They say necessity is the mother of invention.
Don't know who the father is, probably remorse.
Red Green
-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of
charlie hill
Sent: Wednesday, August 20, 2014 12:06 PM
To: Antique tractor email discussion group
Subject: Re: [AT] McCormick plow
wow, that's a rig I've never seen before. The only tractor
I know that pulls a plow up front is an Allis Chalmers G.
Didn't know anyone else ever did that. By the way, I read
once that you push a plow instead of pulling it as I've always said.
I guess if you think about it that is correct because the tongue runs
back to the rear of it and pushes it.
Charlie
-----Original Message-----
From: Ron Cook
Sent: Wednesday, August 20, 2014 10:38 AM
To: Antique tractor email discussion group
Subject: Re: [AT] McCormick plow
Charlie,
No this one actually pulls from the front axle which I wouldn't
do. For two reasons. #1 it looks like a good way to break something
expensive and #2 I don't have that front attachment part anyway. This
plow is probably from a straight A and I think is an A192 plow. The
Super A uses the A193 plow that pulls from the drawbar flipped to the
forward position. Much better idea I think, and I can make that
attachement, or find one and put it on the plow which would be much
easier. None of it is very tough to manufacture. Pretty simple and
crude tool. Must work, though. It is worn out.
Ron
On 8/20/2014 8:27 AM, charlie hill wrote:
> Ron is that plow a single point hitch with a notch cut in the front of it
> that slides into the tractor hitch or how does it attach to the A?
> The single point (with the notch in the tongue) didn't come along until
> the mid 50's to early 60's I think.
>
> Charlie
>
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