raise hst relief valve pressure on tc33 ?

[dynasim]

Schlen,

I think you are probably the highest hour HST guy that I have seen. Could you take a picture of your tractor, and post it?

Does your tractor hold its position when the pedal is centered, and it is on a hill? That would be a good way to tell if there is a leakage problem. On mine, which is one bigger in frame size, on a 1/12 slope hill, it'll move about 1 foot per minute. I would expect that mine will increase in speed(leakage) as time goes by. They are designed for some amount of leak through, so perfect is not zero leakage.

Also, are you sure your clutch is good? I think your model has one, and even if it has an HST, it may very well have finally worn out.

Can you kill the engine by pushing the pedal in all the way. If you can't, and you don't have leakage, or a worn clutch, it is likely that you have a bypass issue, in my opinion, and it would be worth it to check it out. Keep in mind, though, that your 33 is at the upper end of the class size(I think), and therefore, is operating at the limit of the transmission design.

I don't have your same frame size, but I would never characterize my HST as non-responsive. It will give one whiplash if you stop to fast.

Possibly you could go test drive a 33 or 34 at a dealer to get a comparison.

Again, congratulations, and I hope it lasts another 5100 hours.

Chris

 

[dqdave1]

I do not want to hijack this thread; but 5200 hours on a compact - wow! I have not seen or heard of this high amount of hours on a compact. Can you tell us how everything else is doing on the TC. Has engine been rebuilt? How is overall condition of linkages, 3pt hydraulics, loader pivot points. Could it be possible the key was left on by accident and ran the hours up?

When I bought my TC 29 in 1999, dealer guessed I would be good for 3000 hours before it would begin to have many repairs, rebuilds, etc.

 

[dfkrug]

My tc33 has about 5200 hours on it now. the spring at the bypass may have weakened and the components are surely loosened up so I may not be in the best position to pass judgement--however one can tell when a relief valve is popping off as opposed to excessive fluid shear in the transmission.

I agree that the relief valve springs can get "tired" and lose some of their
springiness, which lowers the pressure at which they open. I have seen
that on the main hyd circuit on CUTs with over 2000 hr. For the HST, you
are dealing with pressures in the 4500-5000 range, which are testable at
the guage ports provided. I would be quite surprised if the guage ports are
not accessible without cracking the tractor, though you may have to take
off a lot of other parts first. I have not changed RV pressure on HSTs, but
I have for the main hyd system.

There are considerable intentional internal "leaks" designed into an HST. Most
are on the slippers of each of the pistons on the motor and pump. Oil must
squirt out of a hole in each slipper to lubricate it as it rubs against the end
plates. These leaks make an HST inefficient in transmitting power, but
elegant in their simplicity and reliability. I imagine with good clean oil, HSTs
are good for many thousands of hours.

I have lots of seat time on four different HST models now, and the
differences between how they perform is huge. At least between the brands.
My JD955 would never stall the engine in low range....tires could be spun
regardless of load, weight, and traction. It had new AG tires and a 1200
pound backhoe on it, too. It never went to relief in low range. The 2 Kiotis
had IND tires and both would go to relief without spinning tires (in low).
Finally, my Kubota B21 would bog the engine in low range, rather than
spinning tires OR going to relief. Different design philosophies, apparently.

 

[Thumper & Buttercup]

When we purchased our new tractor I asked about an extended warranty. The dealer said it was a waste of our money, he said only one of the newer NH has ever need any work. That one had over 7800 hrs, it was used everyday at a dairy doing all the work of cleaning the stalls to feeding to all the rest of the work. I think they rebuilt the engine and put her back to work.

 

[RickB]

For the HST, you
are dealing with pressures in the 4500-5000 range, which are testable at
the guage ports provided. I would be quite surprised if the guage ports are
not accessible without cracking the tractor, though you may have to take
off a lot of other parts first.

Testing F and R drive pressures on a NH Class II hydro involves removing the lower RH and LH cowl panels (six 8mm bolts total) and attaching test equipment to the test ports.

It takes longer to warm the oil to operating temps for the test than to get set up and perform. IIRC, the test ports are 1/8" BSPT thread.

 

[schlen]

first lets put the hours in perspective--If I average 30mph for 100,000 miles its only 3333hrs. This tractor is like a truck with less than 200000. one of my dodge cummins has 360,000miles maybe 10000 hrs still starts like new.

I'll create a new thread with some pictures soon because it is an interesting specimen this tractor.

I bought this tractor from a landscaping company for $2500 with loader. It was pretty beat up but started and drove and the loader worked so I couldn't pass it up. I think they figured it was wore out because it was real low on power. adjusted the smoke screw and almost doubled the power. something must've worn or changed in the pump. set it to just before I see smoke under load--I may turn it up. I've never seen a compact with this many hours but the dealer said he just had two come in with 12000hrs--used for mowing at the airport. The engine seems to have full power. It started fine today at 12 degrees--starts as good as my massey at 200 hrs. I would say it is not rebuilt--the company I got it from would sell it before the expense of a rebuild. although it is obvious the tractor was greased and oil changed.
The hour -meter will not run unless the engine is running--I checked.

The clutch is good because the bushhog will kill the engine without slipping clutch.

I can kill the engine with the hst pedal when cold but it takes a second or two--the engine draws down. once it warms up I think the engine will keep running. I'll try the hill test.

Mechanically the tractor is in good shape. The worst is the cosmetic damage to the body panels--everything is loose or busted like they hauled boulders on the hood.
They loader is in rough shape welds and cracks. everything's real loose and wallered out. I'll post pics later.

I broke both lift arms on three-point. could tell the metal was fatigued. I welded the arms but I know it wont last.

steering wheel tilt was busted. 4 or 5 hose clamps on the adjuster shaft fixed that.

oil pan drips a little. power steering pump leaks where it mounts.

lights are all broke. gauges are all iffy and innaccurate.

I replaced the large bearing on which the super-steer articulates. $300
The only reason it went out is the bolts loosened allowing the race to break. one day the whole front axle came out CHECK YOUR BOLTS. they are below and behind the radiator.

the float and center detent on the loader valve just broke.
I've seen several JD 425 with 7500-8000 hours or more and the hydro is good. My JD dealer said the 855 hydro should last 10000 hours. They should last that long with good maintenance and good operator. This tc33 was probably abused by the operators radiator screen not cleaned etc. . .

I'll look into testing the pressures thanks Rick. It'd be good to know where the hydro is at.

 

[dynasim]

Schlen,

Now that is a bargain that I wish I would have found! Did you get it locally? I am in(actually outside) manhattan.

Again, good luck.

Chris

P.S. Do you think the Supersteer is worth it? There have been some questions about its longevity.

 

[schlen]

Yeah I got this tractor from a landscaping company that was reorganizing here in Wichita. It was a good deal but only because it turned out in my favor. I was taking a risk and it is a rough machine.

The supersteer is nice but my tractor has a rocker pedal for the HST and the wheel brakes are on the same side so I can turn as sharp in my massey because with it I can actually use the wheel brakes effectively. It is also easy to tear a tire off a bead if one is not careful. Supersteer makes the loader tricky to maneuver in tight areas if you're not used to it (or even if you are). If I was using a MMM it would be the cat's meow, but for loader work and with a HST I could take it or leave it. I would not question the longevity--just check the bolts occasionally. There are a lot of tie rod type ends but the are beefy and so is the big bearing that lets it all pivot.

 

[SPYDERLK]

I can kill the engine with the hst pedal when cold but it takes a second or two--the engine draws down. once it warms up I think the engine will keep running. I'll try the hill test.

Mechanically the tractor is in good shape.

So many opportunities in your post and never once did you call an engine a motor. You deserve respect!
I am with you on the relief setting as I have a tractor that has been like that since new. I have never tried it cold, as I think engine power is down, pumping losses are up, and full fluid flow across the relief is going to require higher system pressure than at op T. This all adds to a result that can easily mislead unless well thot out, and I think it somewhat abusive to the system if its below warm day "cold". My BX1500 will not stall at full pedal unless its also got a 2 or 3HP PTO load. Good luck with sorting yours out.
larry

 

[RickB]

.
I can kill the engine with the hst pedal when cold but it takes a second or two--the engine draws down. once it warms up I think the engine will keep running. I'll try the hill test.

I'll look into testing the pressures thanks Rick. It'd be good to know where the hydro is at.

Hydrostatic transmissions require cool, clean oil for long life. If the inside of your tractor was cared for like the outside, one has to wonder.

Better performance with cold oil than warm tells me there is internal leakage, not a low relief setting. Relief valve cracking pressure doesn't change appreciably with temp changes, but component clearances and oil viscosity do.

When you do check the pressures, be sure to do a cold test as a comparison to the standard test done at operating temperature. I predict a noticeable difference.