NH TD75D 3-Point Will Not Lower

[downslope]

I have a NH TD75D open station with about 1,000 hours. It was recently parked for about 2 weeks outdoors with the 3-point arms raised (it was being used on a wheel-lift pull disk).

Now with the disk and remotes unhooked the 3 point will not lower.

I should explain that the 3-point was only about 80% of the way raised. The tractor has a lift-limit that was set so as not to bind up the PTO shaft when it was on a 3-point rotary cutter. By using the position control lever I can raise the arms fully the rest of the way (100%), but when I attempt to lower them they will only go back down to the same position where they are stuck (80%).

What can be the problem here and any ideas what I can try to get things working. Thanks for any suggestions.

PS: I had similar problem about 4-5 years ago when this tractor had been stored in barn over-winter with 3 point raised for several months. I don't remember exactly what I did at that time, but I got it to lower by playing with the controls for a while. Since then I've always tried to remember to keep it lowered when parked, but forgot this time.

 

[CalG]

rusty cylinder?

 

[downslope]

rusty cylinder?

I suppose it could be, should I try loading some weight on it, I have some front-end weights and barbell plates.
But if corrosion is a the potential culprit couldn't it also be rust in the control valve or some other internal passage?

 

[CalG]

I suppose it could be, should I try loading some weight on it, I have some front-end weights and barbell plates.
But if corrosion is a the potential culprit couldn't it also be rust in the control valve or some other internal passage?

Well, If the lift cylinder bore is rusty on "the far end", the piston /seal can jamb when stroked all the way LIFT.
The lower part of the lift cylinder sees more oil because it's closer to the splash.
Remember, the lift cylinder is single acting, so rust preventive lube beyond normal lift is iffy.

Now any rust that might be present, and flakes off during motion and comotion, would need to pass through the filters and pump before making it's way to the control valve etc. The fluid "should" be pretty clean by then.

I only bring this up, because It happened to me. You know, anything that happens to you seems so much more likely to happen to the other guy! ;-)

I would use a long bar as a lever "some how", to try to force that cylinder down , making sure the control valve is open to the drop function.

 

[TractorTech]

Is the Lift-O-Matic switch/lever in? Can you manually actuate the lever with the cable on it to externally override the position control lever?

 

[downslope]

Thank you everyone. I got it to lower by loading several front-end weights on the hitch.
I purchased this tractor with 40 hours on it from a NH dealer about 12 years ago (was a demo) and it always seems to have had a problem with water in the transmission/hydraulic sump. In very cold weather (<10°F), the transmission range and gear selectors will freeze up, but not the shuttle. Also, if the NH loader is installed, the raise and dump controls will freeze up in extreme cold.

This is even after changing the oil several times with NH 134 at 13 gallons a clip. The tractor is stored inside 90% of the time, but that’s not to say it hasn't also been occasionally left out in a rainstorm. And who knows how it was treated when out as demonstrator to local municipality running it in parks and on the beach. I guess I'll just dump the oil and filter again and keep going.

 

[TractorTech]

I had a new T4.105F that had a stuck 3pt and was very new. The 3pt was up all the time because it was used for drawbar work.
Similar method to get it unstuck was used.
It is in the southwest desert where moisture is nor a problem.

 

[DieselMonk]

I did the same thing, putting weight on the 3 point hitch.