Traction Hydrostatic trasmissions and braking. (Hills)

[goeduck]

I thought one thing we figured out here was that hydrostatic transmissions don't have neutral. (Neutral)

I think he was talking about the range selector?

 

[Buggs67]

I have some very steep hills, and I operate my Hydro tractor on them. Here is a description of operation on these hills. If you are moving forward at a good clip down hill in 4wd for instance and yank your foot of of the forward pedal, it will practically snap you neck stopping. BUT it will then start to slowly roll down that hill, unless you touch the brakes or apply some reverse pedal. If you shut the tractor off, and the charge pump leaks down, I have heard the hydro will take off down hill and gather speed. I can't testify to this exactly, as I have always hit the brakes. I never wanted my tractor down is some ravine. If you go down this hill in 2WD the tires will start to slip on the gravel surface and can totally lose traction with the road surface. Of course this has nothing to do with Hydrostat, as a gear tractor will do the same thing as engine braking will cause this just the same as the "braking" applied by the hydro. So to answer you question, as soon as you come off of the "go pedal". A hydro should slow you down, some will slow you down really fast. But they will all creep downhill without pedal input.

X2. My tractor doesn't really creep much unless it's a steep hill and then I use the parking brake. On moderate hill it will not creep. But I'll drop the FEL or rear implement to act as a brake ( and relieve energy. A god habit to get into.)

And it's terrifying when you're going down a hill and it's not in 4wd, and the rear wheels just skid. Only happened to me once; now my tractor is almost always in 4wd. and I never need the brakes.

 

[Buggs67]

I thought one thing we figured out here was that hydrostatic transmissions don't have neutral. Seems like you can look at them like a speed control, (and zero is a speed, which they will attempt to meet), or just look at it for what it is, an infinitely variable transmission system that cannot be taken out of gear. Of course, it's true that some hydrostatic transmissions have a gearbox connected to them. And it's common to call the whole assembly between the engine the rear axle a transmission. But this is really a hydrostatic transmission plus a gear box. And while virtually all gear boxes have neutral, a HST does not.

What are the takeaways here?
-If you have a tractor that has a HST, and no brakes, always keep the drive train in top shape. Failure of a coupling, or a hose, could have you sailing down a hill.
-Terramites have a parking brake, keep it working. Although it might not be the best way to stop a runaway, it's better than nothing.
-If you do have a gearbox somewhere in your drivetrain, don't disconnect your your drive train on a hill. (Neutral)

FWIW; my tractor HAS a parking brake as well as brakes. And my tractor has a high and low range with neutral in the middle as well as a clutch with a ctch to leave in in the depressed position.

If Terrimites don't have these features maybe he should be considering a better SCUT or CUT.

 

[Buggs67]

I'm looking to getting a Terramite. My yard has a couple of moderately steep hills.

I rented one once for two days. It was a competent little tractor. Do they still make them or are you looking at a used one?

 

[rsl360]

I rented one once for two days. It was a competent little tractor. Do they still make them or are you looking at a used one?

They do still make them, but I'm looking for a used one.

I've had the fun of sliding down hill on a riding mower with the wheels slipping, but that that mower did not have limited slip. So one wheel would lock and the other would roll. I think with limited slip I'd be ok even with 2WD. Given that I have lots of trees, I do think that the four post rollover protection is a good idea, so I'm considering it a must have.

The lack of a high range does make the Terramite slow. I suppose that having a neutral might save a bit of fuel, since the hydrostatic drive is always "engaged", even when digging. But I suppose you get what you pay for. And it's pretty simple.

 

[MossRoad]

Even though the drive pump is engaged when not moving, it's not pushing any fluid in either direction, so it's not drawing much load at all at that point, compared to the pump that is running that is supplying the hydraulics for the loader, backhoe, steering, etc.....

 

[mogman770]

ok I have a few questions. how about when you start your terramite and sometimes it jerks you 2 feet forward and shuts off? i have a very steep driveway and the things scares the sh-t out of me cause sometimes it jerks forward and starts running away? anything I should look at? hst tranny

 

[MossRoad]

Put it up on blocks and start it. The wheels should not turn in either direction without operator input. If they do move, there's probably an adjustment for the directional pedal(s) and it will have to be adjusted to the neutral position for NO creep when centered. If that procedure doesn't work, then there's something else wrong, like stuck linkages or pump internals.

 

[mogman770]

I will try the thanks for the help Mossroad..

 

[rsl360]

ok I have a few questions. how about when you start your terramite and sometimes it jerks you 2 feet forward and shuts off? i have a very steep driveway and the things scares the sh-t out of me cause sometimes it jerks forward and starts running away? anything I should look at? hst tranny

Just sometimes? Sounds like your drive pedal is sticking. As Mossroad said, might be an adjustment, but if it's only doing it some of the time, sounds more like something is sticking. The directional pedal should always return to the same location, even when it's not running. If you don't feel like you can find the "center" reliably, then that's likely your issue. Also, (and I just have to ask), are you doing something like "giving it a little gas" with the pedal? It's not a throttle, others have been fooled by this, though not quite this way.