# Draft sensing 3 point?



## Hoodoo Valley

Does this mean that the hydraulics push down in addition to lifting? I'm considering buying a John Deere 5205, and really wanted a machine that pushed as well as lifted the 3 point.


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## Country Boy

The draft sensing won't put down pressure on the three point. A three point hitch will never have down pressure, it relies on the weight of the implement or the draft created by said implement to lower the arms. What the system does is dynamically transfer the suction force (draft) of a plow or other ground engaging equipment to the rear tires of the tractor, giving you extra traction. It can adjust how low the plow is to keep the draft equal as you go through changing ground conditions. For example, if you are plowing and hit a hard patch of ground, the plow will try to dig deeper due to the draft load. The three point will respond by trying to lift the plow to counteract that tendency to dig deeper, transferring more force to the rear tires, giving them greater traction to help pull through the rough spot. As you get into lighter soils, it will allow the plow to drop slightly to increase the draft to where it is set. It may be useful in other situations, but plowing is the only job we use draft sensing for here on our farm.

Wikipedia has an article on it here: http://en.wikipedia.org/wiki/Three-point_hitch


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## Hoodoo Valley

Country Boy said:


> The draft sensing won't put down pressure on the three point. A three point hitch will never have down pressure, it relies on the weight of the implement or the draft created by said implement to lower the arms. What the system does is dynamically transfer the suction force (draft) of a plow or other ground engaging equipment to the rear tires of the tractor, giving you extra traction. It can adjust how low the plow is to keep the draft equal as you go through changing ground conditions. For example, if you are plowing and hit a hard patch of ground, the plow will try to dig deeper due to the draft load. The three point will respond by trying to lift the plow to counteract that tendency to dig deeper, transferring more force to the rear tires, giving them greater traction to help pull through the rough spot. As you get into lighter soils, it will allow the plow to drop slightly to increase the draft to where it is set. It may be useful in other situations, but plowing is the only job we use draft sensing for here on our farm.
> 
> Wikipedia has an article on it here: http://en.wikipedia.org/wiki/Three-point_hitch


CB, I've heard of people owning tractors that apply down pressure to the 3 point. Are these folks misled or am I not understanding correctly? I've seen a hydraulic cylinder added as the top link to tractors. Is this what they are talking about?


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## Mickey

Not everything is created equal. While a few tractors may offer down pressure, it's not the norm.

I'm not fully understanding CB's explanation, my understanding is draft control help maintain plow depth. Plow hits some ground condition and wants to cause the plow to dig deeper, the draft control senses the downward force on the 3-pt and applies some lift so as to maintain the set depth. As soon as the condition changes back to the norm, draft control releases some of the up force thus permitting the plow to return to its initial setting.


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## ErnieS

I wonder if we could expand on how to use draft control. As I understand, you put your implement on the ground with the lift control all the way forward, and limit depth with the draft control. With the draft lever all the way forward/down, the implement will try to draw down to the limit of the 3PH, pulling up on the draft lever will raise the lower limit of travel, and cause the hitch to further raise or lower, to keep load on the tractor constant. Is this pretty close?


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## Hoodoo Valley

ErnieS said:


> I wonder if we could expand on how to use draft control. As I understand, you put your implement on the ground with the lift control all the way forward, and limit depth with the draft control. With the draft lever all the way forward/down, the implement will try to draw down to the limit of the 3PH, pulling up on the draft lever will raise the lower limit of travel, and cause the hitch to further raise or lower, to keep load on the tractor constant. Is this pretty close?


I don't know but I'm learning something new here.


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## ErnieS

I hope to LOL. I did manage to collapse and then snap a top link with my box blade. Maybe the proper use of draft control would have saved me that catastrophe. I didn't hear the link snap and backed up with essentially no top link. The box blade rolled over and sunk 2 scarifiers into my rear tires. They didn't puncture, but it sure looked real bad and took me a couple hours to untangle everything. Only real damage was the link and my back up light.


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## Hoodoo Valley

ErnieS said:


> I hope to LOL. I did manage to collapse and then snap a top link with my box blade. Maybe the proper use of draft control would have saved me that catastrophe. I didn't hear the link snap and backed up with essentially no top link. The box blade rolled over and sunk 2 scarifiers into my rear tires. They didn't puncture, but it sure looked real bad and took me a couple hours to untangle everything. Only real damage was the link and my back up light.


Gosh, I lost a pin to my top link hooked up to my box scraper. Same thing as you said...... Headache city. Let a few very precious words fly out of my mouth over that deal.Wife was really impressed. Early on.... I found that when hooking anything up to that 3 point, the first move is that top link, then the bottom. That and check those pins and connections every chance you get. I would up on top of my boxscraper and after struggling for sometime, went ahead and just cut it loose and rehooked.


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## ErnieS

A lynch pin fell out of the inside end of the left lift arm yesterday. Of course I was 250 yards from tools. I had to drop the right side and find a branch to use as a lever to get it back together. Thankfully I had 2 spare pins with me. No damage other than the right arm rubbed the inside of the tire a bit.
Funny thing is, I had checked all the pins when I hooked up the bush hog.


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## Thomas

TB.
"I'm considering buying a John Deere 5205"

I thought Kubota was in first place.


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## Hoodoo Valley

Thomas said:


> TB.
> "I'm considering buying a John Deere 5205"
> 
> I thought Kubota was in first place.


Not in the bigger stuff my friend. Unless otherwise showed up, those Powertechs are pretty darn pissed off sounding!


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## Pipertec

TB, I think on some tractor setups, that Hydraulic cylinder you are talking about where the top link usually goes is actually being used as a "Hydraulic Pressure Sensor". It uses the pressure differential to send input to the draft system to adjust the lift arms to maintain the implement at the proper depth. I've never seen "Down Pressure" on the Rockshaft available before. Draft Sensing is primarily used for plowing. I have seen instances of a Hydraulic Cylinder being used as a top link to set the AoA of the cutting edge of a Box Scraper. It works a lot better on the bigger Box Scrapers because it actually doubles as a top link shock absorber in harder or rockier surfaces.


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## BelarusBulldog

tractor beam said:


> CB, I've heard of people owning tractors that apply down pressure to the 3 point. Are these folks misled or am I not understanding correctly? I've seen a hydraulic cylinder added as the top link to tractors. Is this what they are talking about?


Belarus tractors have down pressure on their three point hitches.  There are other tractor manufactures that offer the same system. I can lift the rear wheels off the ground when I have my rear blade on the back, great for cutting into hard snow banks.  This is a large tracked Belarus tractor with the down pressure system, notice the large hydraulic cylinders controlling the 3pt. There is just a regular top link on this one, but hydraulic ones are available. Bye


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## Mickey

ErnieS said:


> I wonder if we could expand on how to use draft control. As I understand, you put your implement on the ground with the lift control all the way forward, and limit depth with the draft control. With the draft lever all the way forward/down, the implement will try to draw down to the limit of the 3PH, pulling up on the draft lever will raise the lower limit of travel, and cause the hitch to further raise or lower, to keep load on the tractor constant. Is this pretty close?


Sounds like a good explanation to me.


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## ErnieS

One thing I should add is that at least on my tractor, there is a lever next to where the top link mounts that disables the draft sensor. That lever must be dropped down for the sensor to work.


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## Country Boy

ErnieS said:


> I wonder if we could expand on how to use draft control. As I understand, you put your implement on the ground with the lift control all the way forward, and limit depth with the draft control. With the draft lever all the way forward/down, the implement will try to draw down to the limit of the 3PH, pulling up on the draft lever will raise the lower limit of travel, and cause the hitch to further raise or lower, to keep load on the tractor constant. Is this pretty close?



That's basically what I said, worded a bit differently. The draft system tries to keep the plow at the same depth, and it uses the pressure on the hydraulic rockshaft to do so. As you get into harder ground, the plow will naturally try to dig deeper. This puts more pressure on the hydraulics, which causes the system to attempt to raise the plow slightly to keep it from digging deeper and becoming harder to pull. By doing this, it temporarily increases the down pressure on the rear tires, increasing traction to help pull the plow through the harder ground. Its not magic how it increases the pressure on the tires, its simple physics. By trying to pull the plow up from under the ground, the equal and opposite reaction is the tires pushing harder against the ground while the plow pushes up from under the ground. Hitting a rock generally trips the bottom and releases it from digging until it has passed the rock (auto-reset), or until you back up and relock it (non-auto reset) or until you replace the shear pin (shear pin style). This was a radical change from older plows that were of the trailer type and hooked to the drawbar. When they struck a rock or dug too deeply, they could cause the tractor to rear up on its back wheels, and possibly turn over backwards. Sort of like you see at tractor pulls when the tractor rides a wheelie down the track due to the force exerted on the drawbar by the sled. Some plows had a quick release that would release the plow if you hit anything, but Harry Ferguson's design was safer and less hassle than having to back up and rehook the plow every time it uncoupled or worse, turning the tractor over on yourself.

Hope that explains it better.

I've never seen that down pressure system BB. Most newer tractors I have seen just have two large rams under the rockshaft that lift the three point arms, not double acting cylinders. Must be for certain applications like running a scarifier blade or something. You don't want or need down pressure for moldboard plowing.


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## Jbreezy10

Draft is a thing that harry Ferguson invented in the late 30's, it automatically lowers or raises equipment to keep uniform depth. Such as when your plowing and you hit hard packed clay or rocks, the plow raises to keep the tractor from bogging and gettin stuck, and reduces the need for weights


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## MBTRAC

I have tractors wth "down pressure" or double acting rams on the linkage (Belarus & Mercedes ), IMO great for operating a HD rippers for earthmoving or pipe laying but other than this & maybe one or two other very specific task an overindulgence - there's no way I'd be paying extra for this seldom used feature as farm tractor linkages (Cat I/II/II/IV) aren't really designed to support the vertical weight of the tractor on a regularly basis.

A hydraulic top link will make linkage connection quicker/easier & is great in combination with quick hitches &/or hooks, & also good for providing quick tilt adjustment on some implements - though it's not designed nor should it be used to provide "down" pressure (unless you wish to risk breakages/flex on your linkage &/or implement mounts).


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