PT1850 Mowing Techinique

[BWSwamper]

What is the recommended approach to the managing the mower's height when mowing with the PT1850. I was thinking to use the lift to keep the mower just barely suspended with the wheels making contact. However, a buddy whose livelihood is heavy equipment told me I should have the mower running entirely on the wheels (pneumatic front and solid rear) with the tractor just pushing the mower around. I did get a manual, which says nothing about the issue. Didn't call PT on this one question.

The lift was leaking down when I got the machine. We rebuilt all three cylinders on the lift, but still have a gradual leak down. Much better than before, but still leaks down. Is that typical on these machines, or do I need to hunt down a valve or port issue?

Also, found out that Big Dog brand Diablo Mowers use the same front wheel pattern. NoAir has semi-pneumatic replacements with bearings.

 

[SpringHollow]

The PT1850 has draft control that is adjustable. This allows you to adjust how much of the weight the loader arms are lifting. Lifting puts weight on the front wheels which gives you better traction. This especially comes into play on wet steep hills. I would think you would want to be lifting 60 - 80% of the weight.

They all leak due to the type of FEL valve used. On the plus side, it prevents excessive pressure build up when the valves are closed.

Ken

 

[MossRoad]

And I'd guess that leak-down would be a zero factor if you're using the draft control since it would be keeping some pressure on the FEL lift circuit every time the mower weight changes, correct?

 

[BWSwamper]

Thanks.

Could you explain the draft control? I don't understand the manual's description. This seems a bit different from the draft control on my tractor's 3-point hitch system. How does the draft control reference the FEL position?

I was thinking that if the FEL is prone to leaking down, we were going to be repeatedly making minor adjustments while mowing. I hadn't fully realized the role of the draft control.

I've only mowed seriously once thus far since getting the machine, and I didn't use the draft control. I'll use the draft control next time.

 

[SpringHollow]

I have yet to use the draft control intentionally just because I forget to do so and have not had serious traction issues for the mowing I have done with it. I have accidentally hit the switch a few times and notice that my FEL can not lift the load I am working with. It should deal with the leak down issue while mowing. I believe it is just a variable pressure relief valve so it limits the lift capacity of the FEL. I am sure Carl and others can speak to this feature.

Ken

 

[MossRoad]

Thanks.

Could you explain the draft control? I don't understand the manual's description. This seems a bit different from the draft control on my tractor's 3-point hitch system. How does the draft control reference the FEL position?

I was thinking that if the FEL is prone to leaking down, we were going to be repeatedly making minor adjustments while mowing. I hadn't fully realized the role of the draft control.

I've only mowed seriously once thus far since getting the machine, and I didn't use the draft control. I'll use the draft control next time.

Someone with actual experience will have to verify this, but I'll give it a shot. :laughing:

On my little PT425 we don't have draft control. So, pushing a mower along on flat ground, I put the FEL in float, and the mower rides with all of its weight on its own wheels. I'm just pushing it along.

If I head up hill, the center of gravity and weight will shift towards the rear of my machine as the angle increases. Also, the weight of the mower will start pushing back against the FEL arms. If you've ever tried to push into a pile of soil with a FEL loader bucket in float, you'll see that the tractor will try and climb over the FEL if the bucket bites in solid. The front wheels lift off the ground. This is the same force that pushing a mower up hill with the FEL arms in float would have, only slightly less, but its still there. So, the combination of up hill, float, etc... shift weight off the front tires of the tractor and onto the back. You lose traction on the fronts and they start to spin.

So, I pull the joystick out of float, and back just enough to take most of the weight off the mower wheels. This instantly puts more weight on the front tires, I regain traction, and up the hill I go.

Draft control on the FEL arms on the larger Power Tracs does this for you, as I understand it.

It transfers weight from the mower off of the mower wheels and onto the tractor wheels, increasing traction. From what I gather, it's adjustable.

Hope I got it right. :confused3:

 

[MossRoad]

Draft control on a 3pt hitch (at least the one I'm familiar with) monitors the angle of a rock shaft at the point where the top-link connects. If the plow encounters tougher soil, the rear tires start to spin. As the tires spin, they dig a hole in the ground. This changes the angle of the implement-to-tractor, which causes the top-link (the top of the triangle) to want to get shorter. It can't get shorter, so it pushes on the rock shaft. The rock shaft activates a valve that lifts the 3pt hitch so the plow comes up out of the soil. As the plow comes up, there's less resistance to forward movement of the tractor. The tractor moves out of the holes it's digging with the tires, the implement starts to drop down, pulls the top-link, which pulls the rock shaft, which releases the valve on the 3pt arms and they drop back down to where you depth control was originally set.

I don't know how the Power Trac FEL arms sense the load.

 

[woodlandfarms]

Yup, I use draft control all the time. What I believe happens is that the draft control allows a bit of bypass into the arms. So it pressures the arms up a bit but keeps it in float mode. the reaction time is slow, so if you go over a ledge it takes a few moments for the mower to settle down . I augment the movement with the lift arms. So if I am about to go up something steep I will pull up on the arm a bit so the nose does not dig in. Just FYI draft will cause your machine to not start and sometimes you will bump it and then your lift arms won't really work anymore and you will freak out and think your PT is broken and hten you cry and then your wife comes out and you look like a dummy ... ask me how I know.

 

[ponytug]

Woodlandfarms and MossRoadhave it. The draft control circuit sets a user defined pressure in the lift cylinders. This transfers weight off of the mower on to the tractor. This gives the tractor better traction, and much better ground force, in part because you are not trying to push the little wheels on the mower into the ground. (Their axle center is much lower than the axle center of tractor drive, resulting a wasted force pushing them down, as the tractor tries to go forward.)

The pressure that you need is attachment specific. I recommend setting on level ground first. On my 1445, the control is an aluminum block, with a black needle valve and a locking ring, attached next to the battery and fuel tank. With the tractor running, but parked, brakes on, engage the draft control on the dash board, and then open the engine cover. Loosen the lock ring, then adjust the needle valve until the attachment lifts off the ground and then back off some. (User choice) I find that when the oil is hot, I need to adjust the draft control for more lift.

I agree with Woodlandfarms, you learn to anticipate large changes in height, and goose the joystick up or down as necessary.

I can say that for the 72 inch brush hog, it makes for much, much, better traction, and ease of maneuvering on slopes. When it is on, you may notice occasional momentary lags in the steering. This is because the draft control takes oil off ahead of the steering. Totally normal, just like the slow leak down. If the leak down is faster than inches per minute, you may have a bit of dirt stuck in one of the check valves on the joystick. Easy fix; get the area spotless, and remove the check valve cover, being careful not to lose any pieces. Usually, just opening it up is enough to flush the offending dirt particle out.

One really important thing- do not leave the joystick in float when in draft control mode. Float will bleed all the pressure out, and the draft control solenoid will go crazy trying to release oil to bring the pressure up.

All the best,

Peter