Um, what is that gauge for (and other eye-rollers)

[Bob999]

What does an adjustable lift force do?
What good is it?
Can anyone explain how the draft control on the PT works?

My understanding is that the "adjustable force" transfers some (an adjustable amount depending upon the setting of the control) of the weight of the implement (mower) from the implement wheels to the tractor wheels--thus providing additional traction to the tractor and allowing it to operate on steeper slopes than it would be able to do without the "draft" control.

 

[Bob999]

1) Okay, but how hot is too hot? If it sometimes is running at 220, should I be concerned?

I think that if the temperature reaches 230 you should clean the radiator.

I recognize that instruments aren't perfect so another way to think about this is to establish a baseline for your machine--the operating temperature with a clean radiator, and recognizing that that temperature will vary a bit with ambient air temperature, plan to clean the radiator when the operating temperature increases by 20 degrees.

 

[ponytug]

I believe MR's description is correct. The PT draft control is a solenoid controlled variable pressure valve, which generates a user changeable pressure compensation (and you should change it as needed for different implements!). Because it is pressure sensing, it has feedback from the lift arms as the implement moves up or down. Mike O'Connor posted a great description on how to adjust it, in case your PT manual doesn't explain it.

3PT tractors with level control use a tractor or implement reference point to keep the 3PT implement at a fixed height using variable force. They are generally used for soil ripping, plowing, and cultivating fields, where depth control is important.

To the outside observer they seem similar, but are very different in use. e.g. I think that the 3PT fixed height is useless for mowing non-level terrain, but great for levelling it.

Think of the PT as having variable height, while transferring (nearly) fixed weight (force) to the tractor from the implement. This improves the tractor traction (more weight on the tires) and improves the ability of the implement to rapidly follow changes in terrain.

Float hydraulically couples both sides of the lift pistons to each other, allowing hydraulic fluid to flow easily between them. This applies no weight to the tractor.

I know of one PT owner who has a constant height modification. He uses it to level building sites and playing fields, with the fixed reference coming from a fixed survey point. (Pretty slick in my opinion, but not cheap!)

All the best,

Peter

David,

I think your description of draft control applies to a typical ag tractor implementation. I don't think it describes what is called draft control on a PT. My understanding of the draft control on PT is that it provides an adjustable lift force but that there is no feedback mechanism. That is it doesn't "sense" the pressure on the lift arms. This differs from an ag tractor where the control is designed to control the heigth of the implement so that the tractor is applying constant draft (pull) to the implement as it moves over/through the ground.

 

[MossRoad]

Well. I sent an e-mail to Power Trac asking what the draft control does and how it works this morning. About 10 minutes ago my phone rings and Terry from PT called to answer my question.

From what I understand, it works to take some of the weight of the mower off the mower wheels and transfers it onto the tractor. That provides better traction for the tractor and helps to keep the mower deck wheels from plowing into the soil, since large mowers can weigh quite a bit. He also said that it works by sensing pressure. If you go down a dip, the mower will lower and when you go up a dip, the mower will raise. The draft system attempts to keep the same amount of pressure on the lift circuit based on changes in the pressure in the lift circuit. So it does sense something and make an adjustment.

He also said that you cannot use float and draft at the same time.

This seems very similar to my old 3PT setup on my tracto. I set the depth of the ground engaging implement, then set the draft control for sensitivity. If the plow dug in so much that the tractor would start to rotate over the rear axle, that would shorten the rockshaft, which would raise the 3pt arms. Once the rockshaft went back to the operating position, the 3pt arms would lower back to the depth I had set. The sensitivity level would dictate how fast that correction would take place.

It seems that the major difference between that setup and the PT draft setup is that instead of a mechanical rockshaft making the feedback, PT is using a solenoid and pressure relief setting.

 

[KentT]

Well. I sent an e-mail to Power Trac asking what the draft control does and how it works this morning. About 10 minutes ago my phone rings and Terry from PT called to answer my question.

Wow, you must be VERY special to get a phone call in response to an email... But, we knew you were special all along...

So, did you ask him how we could add draft control to our 425s?

 

[ponytug]

Hey! Terry calls back every time that I call him, and Kristie was equally good when I was buying the PT.

Now responding to email is a whole different ball of wax/kettle of fish/...

Thanks for asking PT, Dave! It always helps to get the word from the horses mouth.

All the best,

Peter

Wow, you must be VERY special to get a phone call in response to an email... But, we knew you were special all along...

So, did you ask him how we could add draft control to our 425s?

 

[woodlandfarms]

IMO, I put very little faith in the guages that are provided with the PT. Its not that they are bad, just maybe not completely accurate. I had an old 64 Kaiser Jeep Wagoneer (first year built) and it ran great, until it overheated. Which according to the guage was not about to happen. It turns out the sensor was bad. I guess even digital can be inaccurate, but I like to live with the belief that modern technology rules ;-)

220 is about what I run when mowing on a super hot day. I think you need to consider a couple of the air movement mods, do a bit of cleaning, and maybe invest in a thermal sensor (looks like a toy gun you point at the device).

Carl

 

[MossRoad]

So, did you ask him how we could add draft control to our 425s?

We discussed that a little bit. He said they used to put it on the smaller machines but they stopped doing it a long time ago. They believe it is only needed on the 30HP and up machines because of the weight of the mower decks increasing.

The only time I see my mower deck wheels on our PT425 sink in the soil is when going up on really soft, highly erodable sandy slopes. However, I'll bet if you offer them a pile of money, they'd be happy to do it. You could ask him what it would take to do it, I suppose.

 

[MossRoad]

...Now responding to email is a whole different ball of wax/kettle of fish/...

He said he was handed an e-mail and my phone number was in my signature, so he called me. I was pleasantly surprised. I hadn't talked to him for several years and didn't expect him to take the time to reply in person. Nice folks over there in Tazewell.

 

[Bob999]

The PT draft control is a solenoid controlled variable pressure valve, which generates a user changeable pressure compensation (and you should change it as needed for different implements!). Because it is pressure sensing, it has feedback from the lift arms as the implement moves up or down. Mike O'Connor posted a great description on how to adjust it, in case your PT manual doesn't explain it.

Peter,

I think we are converging on our understanding/explanation of the PT draft control. However there is one item in your description that I hope you will expand on a bit more. This is the statement that "Because it is pressure sensing, it has feedback..." I understand the PT draft control to be variable pressure--but not "sensing". This differs from my understanding--I don't think there is an active feedback--rather the adjustment simply varies the pressure applied to the lift cylinders. Further, in my experience that pressure is not constant but varies with engine speed.

I understand that David's description of the explanation provided by Terry talks about "sensing" pressure. However--my question is where and how is the "sensing" taking place.

To expand on my model of how it works--the adjustment varies the pressure applied to the lift cylinder and the operater adjustment is to set the adjustment pressure so that the majority of the weight of the implement is transferred to the tractor. This allows the implement to follow ground contours with no active feed back mechanism--if the ground drops the implement drops because a properly adjusted control only supports a fraction of the weight of the implement. Similarly if the ground rises the implement rises because the ground is "pushing" it up. Again no active feedback mechanism.