goeduck
Super Member
This ^ sums it up well.
Traction Hydrostatic trasmissions and braking. (Hills)
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CalG
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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.
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
Member
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.
"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.
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k0ua
Epic Contributor
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.
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
Member
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
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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
Veteran Member
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
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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.
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
Epic Contributor
Agreed. I think the technical term for that is "broken". Or maybe "messed up" :laughing:
OP
rsl360
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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
RSL360