Hydrostat mystery??????

1641 · Aug 12, 2004

My 1641 won't back up right. To get the tractor to back up under load (uphill too) you have to rev it up pretty much to the max. The only adjustment I can see for the problem is in the linkage. But to adjust the linkage to gain power in reverse, you lose your forward speed. Right now I have the linkage set to give me the MINIMUM acceptable reverse capability and the top forward speed on the tractor is not much more than a fast walk.

Is there another adjustment on the hydro?? The machine has 225 hrs. on it so it should not be a case of wear. The fluid & filter wer just serviced.

1641 · Dec 24, 2004

BTT.

Just in case.......... /forums/images/graemlins/grin.gif

DmansPadge · Dec 24, 2004

Is it belt driven or shaft? It might just be time for a new belt as the old one might have stretched.

1641 · Dec 26, 2004

Nope. This is a shaft-driven tractor. Good thought, though.

riches139 · Dec 27, 2004

Check your pump release lever.(To be able to push tractor if it breaks down).
May be bypassing somewhat.

fullpull1782 · Dec 28, 2004

I have a bigger model (1782) that did the same thing. It does have a different hydro pump (Sundstrand) than yours (Hydro Gear) but my info may apply.
The hydro shift linkage has two springs that apply force to move the trunnion arm of the hydro(an inner and outer spring) The inner spring was broken(thus shorter) and didn't force the trunnion to move as far(so slower,weaker reverse and poorer climbing hills etc) New springs and I was back in business.

1641 · Dec 28, 2004

Thanks fellers!!

Will have a look at both possibilities.

kozak · Dec 28, 2004

Was just looking at a somewhat similar post at a different forum. Not saying this is the problem BUT....if you just had the hydraulic's serviced, just MAYBE it is entrained air in the hydraulic system. I had a problem where my ACCO stopped moving period. In your case MAYBE, it might be a SMALL amount of air that was not bled out completey when replacing the hydraulic oil. (I am assuming you had the oil replaced) So although you are still getting some power transfer, when you require more power, the air in the hydraulic system is impairing efficiency. Just another thing to consider.

MBDiagMan · Dec 30, 2004

If this is the FIRST time that you've changed the filter on the hydro unit, then it is probably damaged internally. You have to change at least the filter every 50 hours.

Best of luck,
Doc

1641 · Jun 7, 2005

Well........here's the update on this situation, at long last.

I could find no obvious solution to the problem. So I took the tractor to a local fellow who works on tractors in the evenings. Initially, he found that the dealer had serviced the tractor with the wrong hydro filter and the incorrect type of fluid. But even fixing those two goofs did not solve the problem. The pressure within the hydro unit was within spec. He removed the tin and said he could get the tractor to back up a hill or a tree by running the hydro arm at the case with a pair of visegrips. But with the linkage (which had a broken rivet on a mounting bracket, which got spot welded) the machine still would not back up satisfactorily. So he got a bunch of manuals and specs and updates sent to him by a buddy at an International dealership. The lightbulb went on!! Long story short......the linkage had been disassembled by someone at some point. They reassembled it incorrectly........completely altering the geometry of the linkage and not allowing it to give full throw to the hydro lever. The tractor runs like a bear now............$500 later.