Traction Hydrostatic trasmissions and braking. (Hills)

[rsl360]

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

I've never driven a machine with a HST, but as I understand it, when you have the foot pedal in "neutral", the machine should be somewhat locked, correct? I realize that there might be some leakage, and thus creapage, but the machine should be resistant to rolling, right? I would expect it not to just roll freely downhill.

I have a friend who has a Terramite T5C, and he says that his Terramite simple rolls down hills. (his yard is basically flat, so it does not matter. There is just one small drop of a couple of feet at the end of the driveway, which is where it rolls.) He says that driving it in my yard would be terrifying. Is this normal, or is his machine somewhat broken? It works fine for him, but I agree, it would not work in my yard. Is this normal for Terramites?

RSL360

 

[prof fate]

all the hydro's i've had will not move in 'neutral' or when off. all have some override, most have parking brakes (maybe all..can't recall..don't use it if they do).

I have a Kioti CK3510HST coming today - the test drive at the dealer they don't use the parking brake either...foot off pedals (one each for F, R)and it sits still.

I'll be able to let you know about 15 minutes after they deliver it (today i'm told...promised..today!!) as I too want to know.

 

[747driver]

My CK 27 will roll if left on a incline and the pedal in neutral. I either set the brake or put the bucket or box blade down. I don't believe the hydro system has a brake system built in to stop it from rolling.

 

[rgr33]

Same here, stays put on flat ground, rolls slowly on a hill. Best to get used to using the parking brake, especially if working near the machine.

 

[davrow]

Neutral is neutral, not park. It is resistant to rolling because it has to force the pump to work, but it is by no means safe to leave on a hill without other means to keep it stopped. As 747driver says, putting the bucket down is one way. And yes, I always use my brakes, even on level ground, to make sure my tractor doesn't run me over when I walk around it (engine running).

 

[Deere Dude]

Same here, stays put on flat ground, rolls slowly on a hill. Best to get used to using the parking brake, especially if working near the machine.

Good advice. Even in neutral my two will roll slowly down a grade. I need to remember that from time to time because I will park the tractor and can have my feet in front of the rear wheels. Could be a disaster.

I have a steepish hill where I just take my foot off the gas and the engine and transmission braking will allow the tractor to move 2-3 mph down the hill.

 

[rsl360]

Neutral is neutral, not park. It is resistant to rolling because it has to force the pump to work, but it is by no means safe to leave on a hill without other means to keep it stopped. As 747driver says, putting the bucket down is one way. And yes, I always use my brakes, even on level ground, to make sure my tractor doesn't run me over when I walk around it (engine running).

Thanks, that's pretty much what I thought. The Terramite only has a parking brake, which does not look like something you would use control your speed when going down a hill. (correct me if I'm wrong.) But no "brakes' per-say. So to go down a hill, you just drive slowly and the transmission restrains the tractor, yes? Neutral is not so much "neutral", as it is a speed of zero?

Anyway, it sound like my friends Terramite is not right, his just zooms down a hill like it's freewheeling. Do the Terramites have a transport or relief valve, that could be set wrong or broken? I suppose the hydraulic clearances could just be really sloppy. Since he does not have any hills to speak of, he does not run into the issue of not being able to get up them. Basically, the tractor works well for what he needs to do. If it lacks drive torque, he might never notice.

RSL360

 

[DoubleO]

I've got a T5 (1984 ish) and a T9. The center position of the pedal is zero speed. It does stop on the hills, but both will creep. Only the T9 has a parking brake. They didn't install them on the old T5's.

 

[k0ua]

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.

 

[davrow]

So to go down a hill, you just drive slowly and the transmission restrains the tractor, yes? Neutral is not so much "neutral", as it is a speed of zero?

We may be in agreement... but, neutral really is neutral. The transmission is not engaged to the wheels. It will roll easily.

When in gear, centering a treadle pedal is 'zero speed'. The transmission is attached to the wheels, but the hydro isn't pushing fluid (swash plate is flat) so the tractor doesn't move under its own power.

Never go down a hill in neutral, your tractor will run away from you.

As you said. to go down hill leave it in gear and accelerate to a comfortable and controllable speed. Centering the treadle pedal will stop the tractor... but it won't hold it.

 

[goeduck]

Neutral is neutral, not park. It is resistant to rolling because it has to force the pump to work, but it is by no means safe to leave on a hill without other means to keep it stopped. As 747driver says, putting the bucket down is one way. And yes, I always use my brakes, even on level ground, to make sure my tractor doesn't run me over when I walk around it (engine running).

This ^ sums it up well.

 

[CalG]

Let us get this STRAIGHT!

If you are in the operator's station with your foot on the hydro pedal, Forward is forward, and reverse is just a foot movement away.
That is, when under operator control there is NO free wheeling or coasting of any kind.

When standing, with the engine running and the hydrostatic transmission engaged (not the same thing with clutched hydro drives)
Any tractor will "creep" depending on the hydro control bias.

With a hydro drive and the engine off, Gravity wins! There is a certain amount of resistance to begin any movement, But setting the brake is the first step to halting a run away.

 

[DoubleO]

No, if your foot is off the pedal, the tractor stops. But it can and probably will creep down the hill.

"Never go down a hill in neutral, your tractor will run away from you." Not true. It can internally leak hydraulically and eventually might freewheel. I've never had this happen. I did park the T5 on a hill, motor off, one outrigger was down but not lifting the machine. The next morning the machine had moved about 10 feet.

The older Terramites had a blue plastic coupling between the motor and the hydraulic pump. They wear out over time. I had always feared that it would strip while under load and then it might go into a freewheel situation.

 

[k0ua]

Lets define a couple of things. A hydro transmission setup in these "normal" tractors consist of the hydro unit, which is a pump and a hydraulic motor which is then coupled to either a 2 or 3 speed standard old gear transmission, which is coupled to the wheels thru a final reduction drive. SOOO. lets be clear what we are calling "neutral". They hydro pump has a swash plate inside whose angle can be varied. When the swash plate is flat and the slippers and pistons are just rotating and not pumping either way then the "pedal" is said to be "in neutral" This is NOT the same as the gear transmission being in neutral. With the swash plate flat and no input from either pedal the hydro unit will still oppose being rotated so it will brake. BUT if you throw the gear transmission that is after the hydro unit in neutral, then there will be no braking and the tractor would freewheel down any hill.

So lets not confuse "neutral pedal" with the following gear transmission being in neutral.

Many people don't even understand that there is a simple 2 or 3 speed gear transmission after the hydro unit, because it is often called the "range selector" but it is nothing more than a simple non synchronized gear transmission.

 

[DoubleO]

Terramites have the hydro transmission and that connects to a hydro motor on the rear end. There is no multispeed transmission inbetween. That is why they go so slow.

 

[Gary Fowler]

I sure wouldn't buy or operate any motorized vehicle that didn't have brakes. Like one post said, if the plastic coupling strips, there is not even a bit of hydraulic braking to be had and if no brakes, you better hope you have some kind of FEL, blade, disc harrow or something that can be lowered to the ground to stop you.

 

[davrow]

Terramites have the hydro transmission and that connects to a hydro motor on the rear end. There is no multispeed transmission inbetween. That is why they go so slow.

I was beginning to wonder if this might be the cause of confusion. My "shifter" has 5 positions: Low, neutral, medium, neutral, high. Centering the treadle pedal, as James clarifies, is not neutral on our tractors... it is "centering the pedal".

If Terramites truly have no neutral little of what I have said is relevant.

 

[MossRoad]

The terramite is very similar to my Power Trac in that both don't have a transmission at all. They both have a variable volume pump that provides forward and reverse hydraulic flow and pressure to drive motors.

In the case of the terramite, there's one drive motor connected to the shaft of a differential, whereas the Power Tracs have 4 wheel motors, no shafts, and no differentials.

Since there's no transmission and just a pump, there's no "neutral" like you conventional HST guys are thinking.

There's just a center position where the swash plate is not pushing fluid in either direction, but still holding pressure in the system. When you center your directional controls, the machine should come to a stop on flat ground. On steep hills, it should still stop, but will probably creep downhill with the weight of the machine. Never trust the machine to hold itself on the hill. Always set the parking brake and lower any implements.

If someone has a terramite that rolls downhill at a fast pace when the directional control is centered, there's something wrong with the machine.

 

[k0ua]

The terramite is very similar to my Power Trac in that both don't have a transmission at all. They both have a variable volume pump that provides forward and reverse hydraulic flow and pressure to drive motors.

In the case of the terramite, there's one drive motor connected to the shaft of a differential, whereas the Power Tracs have 4 wheel motors, no shafts, and no differentials.

Since there's no transmission and just a pump, there's no "neutral" like you conventional HST guys are thinking.

There's just a center position where the swash plate is not pushing fluid in either direction, but still holding pressure in the system. When you center your directional controls, the machine should come to a stop on flat ground. On steep hills, it should still stop, but will probably creep downhill with the weight of the machine. Never trust the machine to hold itself on the hill. Always set the parking brake and lower any implements.

If someone has a terramite that rolls downhill at a fast pace when the directional control is centered, there's something wrong with the machine.

If someone has a terramite that rolls downhill at a fast pace when the directional control is centered, there's something wrong with the machine.

Agreed. I think the technical term for that is "broken". Or maybe "messed up" :laughing:

 

[rsl360]

OK, thanks to many this all makes sense now. I think one way to look at it is to remember that the pedal on a HST is a speed control, and zero is a speed. "When in the middle, go zero mph.".

RSL360