[AT] more HP guaranteed!/now front end on the ground.

Cecil Bearden crbearden at copper.net
Fri Mar 17 04:06:25 PDT 2017


Back in the early 70's I was in Ag Engineering at Oklahoma State Univ.  
I had the hardest time understanding why we would want 10 - 15% 
slippage.  Finally one of my professors explained it as you need that 
much to get the dirt to build up behind the tractor tread enough to hold 
against the tread bar lug.  A lot of times when trying to figure how 
much production the tractor is getting, the speed is taken from the 
hourmeter or the speedometer on the tractor multiplied by the width of 
the implement.  If that 15% slippage is not included, then the estimated 
production is way off.   When I was there we had a test machine that had 
one chisel shank in a trough with a conveyor belt below.  The machine 
would fill the trough with soil and compact it before the chisel was 
pulled through it.  The chisel was fitted with sensors and some type of 
radioactive material was in the soil also.  It was supposed to give us a 
force on the chisel at  various speeds.  It showed when doing tillage, 
doubling the speed, tripled the horsepower requirement.  This was in the 
days that the big 4wd tractors were just being built.  This was the 
start of the 40ft wide chisels and triple grain drill hitches.   If I 
could have found a manufacturer that would hire me, I would have been 
working for a tractor manufacturer.  Little did I know that Massey was 
about to go under, and Allis was being ripped apart by the Germans.

Cecil in OKla


On 3/16/2017 7:47 PM, John Hall wrote:
> To me its a different world when using 3 pt tillage tools, as they tend
> to pull down on the tractor increasing traction and contributing to a
> wheel stand. The last field I chiseled saw the front end come up so fast
> I couldn't even attempt to stop it or let it down easy, it was
> practically instantaneous. Several times I ran out of traction and
> started spinning, but that normally happens slowly. When I start
> spinning I either raise the machine slightly or let it spin through the
> "tight" ground---one of those thing you decide at the moment as to how
> the tractor is handling it. Eventually I want to make a weight bracket
> for the 4020, if you have ever hung the factory weights on one of them
> you know how bad of an idea stackable bolt on weights are. I've got
> plenty of suitcase weights I can borrow off my grain drill.
>
> John Hall
>
> On 3/16/2017 1:42 PM, charlie hill wrote:
>> Here you go, for anyone who feels like working through the math.
>> http://www.agmachinery.okstate.edu/tractors/TractionTractorPerformance.pdf
>>
>> -----Original Message-----
>> From: Stephen Offiler
>> Sent: Thursday, March 16, 2017 1:10 PM
>> To: Antique tractor email discussion group
>> Subject: Re: [AT] more HP guaranteed!/now front end on the ground.
>>
>> Talking about slip... rang a bell.  Ah-ha, Nebraska tractor tests.  They
>> include % slip in the drawbar test.  Without actually checking, my memory
>> agrees with Charlie's stated 10-15% range.
>>
>> SO
>>
>>
>> On Thu, Mar 16, 2017 at 12:52 PM, charlie hill <charliehill at embarqmail.com>
>> wrote:
>>
>>> Just my opinion but I think sometimes when your front end is coming up
>>> while
>>> pulling a load it is from not allowing enough wheel slip.  I read an
>>> article
>>> in
>>> Progressive Farmer many many years ago about proper wheel slip for maximum
>>> efficiency.  If I remember right it was somewhere in the neighborhood of
>>> 10
>>> to 15%.
>>> Air pressure is the key and it varies by soil type.  I just don't remember
>>> exactly what the specifics are.
>>>
>>> Charlie
>>>
>>> -----Original Message-----
>>> From: John Hall
>>> Sent: Tuesday, March 14, 2017 8:11 PM
>>> To: Antique tractor email discussion group
>>> Subject: Re: [AT] more HP guaranteed!/now front end on the ground.
>>>
>>> To be honest, I have no idea. Come to think of it I had one of the rears
>>> repaired last year (new tube and patch the rim around valve stem), and I
>>> don't remember if I checked to see if both sides are equal. Wouldn't
>>> hurt to check. I'm down right now until I get the new radiator
>>> installed. I will say we don't really let the sidewalls bulge out much
>>> when pulling heavy loads.
>>>
>>> John
>>>
>>> On 3/14/2017 12:02 PM, charlie hill wrote:
>>>> John,  how much air pressure do you run in the rear tires?
>>>>
>>>>
>>>> Charlie
>>>>
>>>> -----Original Message-----
>>>> From: John Hall
>>>> Sent: Friday, March 10, 2017 4:19 PM
>>>> To: Antique tractor email discussion group
>>>> Subject: Re: [AT] more HP guaranteed!
>>>>
>>>> Thinking it might give the 4020 more pep than a turbocharger. Course I
>>>> can't keep the front end on the ground as it is pulling the chisel plow.
>>>> Gonna need more front end weights I guess.
>>>>
>>>> John
>>>>
>>>>
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