[AT] Three point hitches and Dean's commentary

[Dean VP]

Grant:

Appreciate your comments and none of the two cylinder era three point
hitches of any variety had power down that I am aware of. I'm not sure of
the 40 through 430 series tractors but I doubt they had it. I know on some
tractors the operator could use the three point as a jack. In fact I think
Ford/Ferguson sold an accessory for this very function. I'm not familiar
enough with the other manufacturer's products to know which had the power
down feature. I surely can see where the power down feature would be very
helpful at times. 

The load sensing feature was more important for the smaller tractors such as
the Ford/Ferguson and the JD 40. They tended to be light in the rear end and
the increase in traction provided by the three point was mandatory. That
wasn't as critical on the larger Two Cylinder Row Crop tractors since the
typical weight distribution was 70% to the rear. The early power lifts on JD
were either all down or all up. Then the power-trol allowed control of the
in-between but no real closed loop depth control. That is why gauge wheels
were required on the implements. Then the 20 Series tractors gave full three
point closed loop control and the gauge wheels were not needed as much.

However, I have had a personal experience with my 620 when plowing where the
added traction provided by the active three point was an absolute necessity.
We had a local club plowing day here one spring where it had rained and was
raining. But us goofs plowed anyway. Those with tag-along plows couldn't
plow at all and those that didn't have their three point hitches set
properly had extremely high wheel slippage. I plowed behind a JD 4440 with a
3 bottom integral plow whose hitch was not setup properly. I too was plowing
with a three bottom integral plow right behind. And the left rear tire lugs
on my 620 were about gone. The 620 with a properly set up hitch crawled
right up onto the back of that 4440 all the time. I would have to stop and
wait so they could get far enough ahead. That tractor probably has more than
twice as much HP as my 620 but it wasn't getting enough traction help from
the hitch. The wheel slippage on the 4440 was atrocious even with better
tires. The increase in traction I was getting from the hitch was very
noticeable. I could hear and feel the hitch working. 

Also the load sensing is very important when plowing with a limited HP
tractor. If the tractor is working close to its capacity and then hits a
really tough spot, one could run out of power real quick. With load sensing
the plow lifts a little to reduce the load and in turn also provided more
traction. I am a firm believer in the attributes of a completely functional
and active top link on a three point hitch. 

The 801 version of the 800 series hitches called a traction-trol hitch had a
mechanical means of detecting load and as the load increased the system
would try to reduce the depth slightly or at least stop the implement from
going deeper. JD advertised a 30% increase in traction due to that
mechanical leverage system. 

No aftermarket hitch that I am aware of mounted on a JD A, B, G, 50, 60 or
70 can provide that kind of capability. Now I agree on many three point
implements that load and depth control is not needed or desired. In fact on
the 801 hitch there was a way to lock that capability out. One of the
interesting side effects that JD had trouble with on the 801 hitch was that
operators would have difficulty getting some plows to penetrate the ground
due to the way the 801 hitch floated. Since there was no down pressure and
the 801 hitch would allow the plow to drop perfectly flat on the ground the
plow shares and points had to be in a good sharp condition and set properly.

You have correctly pointed out that all the features of a conventional three
point hitch may not be needed in this person's intended applications.  



Dean A. Van Peursem
Snohomish, WA 98290

What people can dream, people can do! George W. Bush

www.deerelegacy.com

http://members.cox.net/classicweb/email.htm




-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Grant Brians
Sent: Friday, May 21, 2004 12:21 PM
To: Antique tractor email discussion group
Subject: [AT] Three point hitches and Dean's commentary ...snip



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