Broke Hydrostat twice? Why?

[Grandad4]

Don't know if it has been brought up yet but another aspect of operating a hydrostatic drive is how you operate the "go pedal". Everyone who drives a car is programmed to press harder on the gas pedal when the vehicle needs more power. But doing that on a hydrostat tractor is exactly the incorrect thing to do, and if you've been operating the tractor by pressing down more on the pedal when the tractor is under load (i.e. going up a hill or pulling an implement, etc.), that may have contributed to the problems you've had.

Here's why pushing the pedal down further is the wrong action to take. First, we all know that pushing a car's gas pedal more increases the engine rpm and power output, so you increase the pulling power going to the drive wheels. But a hydrostat does not change the engine speed or output on your TYM at all, but instead it effectively varies the gear ratio of the transmission so more pedal is like having a taller gear (higher travel speed but less pulling power), and less pedal gives more gear reduction (low ground speed and higher pulling power). So, counterintuitive as it may seem, when the tractor is working harder, you should back off the pedal rather than pushing it to the floor.

If this is something you already knew, pardon the didactics, but I thought it worth mentioning just in case.

 

[crazyal]

I would be interested in what you find out. When you say they replaced the HST do you mean they replaced the drive motor? Do you mean the hydraulic pump? Or both as a unit? I've never seen one taken apart so I'm curious. I've always assumed that the hydraulic drive motor was used for both forward and reverse. I would be stumped to come up with a reason why it works in reverse but not forwards (I think that's what you said was happening). I could see the swash plate malfunctioning so it was only moving between neutral to reverse but not forward. Either way I would get the old one for parts, even if you have it turn down it still could have the key piece needed in the future to avoid buying a new hst unit.

 

[Bob Christensen]

Thanks, Grandad4,
This is something I actually know, but only because eight years ago someone else explained it

 

[Bob Christensen]

Well,Crazyal,
The dealer said they were going to replace the 'hydrostat'. And the rear remotes showed 1800 psi upon test.
So I THINK it didn't include the pump or pumps.
But throughout this whole process, I'm not especially proud of my thinker.

Anyway. I hope to get to the bottom of this fairly soon, and I'll definately report back in as much detail as I can.

 

[GManBart]

His tractor only has high and low ranges one of the reasons that when I was looking for a tractor I made sure it had 3 ranges. Having used my father's tractor a lot over the years it always seemed like low range was too slow and high was too fast. Working the tractor in the wrong range would be my guess as to why HST's fail based on my limited expierence with my father's tractor.

This is something I've said many times, and a lot of folks debate. I think the smaller machines need 3 ranges more than the big machines, because the small machines don't necessarily have the torque to use high range effectively for anything but level ground with no load (really just a transport mode).

 

[Coyote machine]

Bob,
I'd suggest not blaming yourself for the hydro failures on your machine. Certainly overheating the HST oil could contribute to premature failure, as could low RPMs in combination with possible overheat condition.
I would strongly suggest installing at least a analog or digital trans oil temp gauge to be able to see where the trans oil is at under different types of work loads. And getting your old unit back, for possible spare parts would be cheap insurance against possible future failure cost mitigation. Fixing or replacing your grille could help keep the chaff from jamming the trans cooler fins. When you hose everything out let the cooler and radiator come to ambient temp instead of shocking them with going from hot to cold with the hose.
DF Krug's offer, I would take up in a heartbeat.
better to know than wonder, and it could once and for all answer why 2 HSTs so far.
I agee with the 3 speed HSTs for the smaller tractors. Two is not enough and high is only for road travel use, not for work.
You may well have to change other things you now do with your machine. It is quite possible you're using it to 'bulldoze', for example, and over running it's capabilities. If this is at all pertinent to your usage, you could be looking at similar bad outcomes in future.

More fluid flowing through HST is best.
Correct range selection, L vs. H, and less pedal pressure under load; instead increase RPMs, and less chunk each go at the mountain, will serve you and your TYM better.

As an aside, my first tractor ownership was in 2009, a 35 HP 3 cylinder Kioti, DK-35 HST. It was a great little tractor but proved to be under powered for my tasks. Consequently I bent parts of the loader brackets, got new ones, bent those, reinforced them too, and so on. Within a year I learned the tractor was great, the operator wanted King Kong, but only had mighty mouse.:laughing:
So I took a beating and traded up to a 4 cylinder 40+ HP Kioti, which had 2750# loader lift capacity. Haven't broken any loader parts, yet.

My point is, if you can't trade it for more capacity, all you can do is make sure you give it attention to it's capacity by lesser loads and more trips etc. Hope this helps.:thumbsup:

 

[Bob Christensen]

Coyote machine,
That's a heckofa post. I'll try to answer your points in order.

1) oh yes I can blame myself. When I first got my tractor, I had to get rid of the slash from eleven semis of marketable timber - mostly 3 foot grand fir.
Unfortunately, about then I read about the German gardening concept called hugelkultur, and anyway my wife wanted a veggie garden.....
So I dug a hole 6 feet deep and 60 feet across and filled it with the slash ( there was a burn ban on at the time). When I hit the hard pan, i couldn't cut through it, try as I might even with a tooth bar. So I ripped into it with the box blade' rippers and this eventually worked. Then I put back some of the fill and all of the topsoil and now really have a spectacular garden.

Took over a month and I'm betting that that sort of thing caused my first hydro to go belly up.

I've been much more careful and gentile since then.

2) yes, I will install a temp guage.

3) yes. I have called Jordan and they are sending me the old hydro Monday.

4) I don't hose the radiators out. I've made a cleaner out of an 18 inch piece of brake line with a short right angle at the end. Connected to my air compresser. Does a heck of a job. I can't believe it leaves anything behind. I'm now cleaning it every 4 hours or so.

5) yes. I'm going to fix my grill.

6) yes. I have sent Dkrug a PM. Not sure I did it right though.

7) Bulldoze. Yes. See above.

I have a couple more comments and some questions regarding fluid flow and such, but my wife just climbed into the hot tub and I feel so dust incrusted from my home made radiator cleaner.that I'm going to
climb in.

 

[Bob Christensen]

Ok, that's better.
I've got a serious question.
Like today I spent about 10 hours moving dirt. The task is to move about 20 cubic yards of fill dirt from a pile to a site about 300 yards down the gravel driveway and dump it over a downslope in an effort to create a level sitting area.

The driveway is almost level. Maybe a 1% grade.

Iam (now) always using low gear and 4 wheel drive when loading and leveling. The tractor has no difficulty picking up a full load. It's only a four foot wide bucket. I used to use high gear for loader work if I thought I could make it work, but with this thread and all I'm not doing that anymore.

I also used to run 1800 or so RPM but now I'm at or nearly at PTO speed of 2600.

The question is this. Can I run in high on the driveway? The tractor feels happy and no longer makes bad whining sounds. Just a very little hydro whine. No bogging.

Sometimes I have a quarter mile between start point and end point. If I have to use low gear all the way, well low is really slow. Remember, I'll soon have a tranny temp guage to tell me what's going on.

On the other hand, the new RPM with my foot on the floor is a little too fast for my driveway. Am I better off lowering RPM to say 2200 or lifting my foot a bit? Does lifting my foot cause heat?

As I explained before, a bigger tractor isn't an option.

I'm done for now. G'night all

Bob

 

[Coyote machine]

I don't think you necessarily need to use full PTO RPMs to do most tasks. Somewhere in the over 1800 you used to use, depending on the load, terrain and ambient temp. 10 hours is a lot for most homeowners, non-commercial users, to do straight through.
Use high for level or downhill transport, and taper the ground speed by pedal, and run highest RPMs while doing the task at hand; ie. scooping and lifting the dirt. Take some breaks, and let the engine run a few minutes before shutting it down between breaks, at a lower RPM near idle for the machine to cool down before shutting her down. You'll be more alert, the machine will respect you more, and you'll still accomplish a lot of work. Plus, during down time you can grease a few zerks or tighten up some bolts, etc. Do a walkaround, check tire pressure, take note of any maintenance issues upcoming, look for fluid leaks, etc.

 

[MinnesotaEric]

Go to your local fleet store and look for a set of radiator cleaning wands. One is for use with a hose and one is for use with your air compressor. They both work really well at blowing dust and debris out of radiators, oil coolers, AC condensers and such. The cost is around $25-30 for the set and they work better than other wands.