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Discussion Starter #1
OK,I have GTH27V52LS and I think it's a good machine.Yea,couple dislikes with it,especially the brake rattle,but have a question to anyone that's had the vari-belt drive.

This is my first tractor with a hydrostatic drive that uses oil to propel it.I guess the more (gas) you give it opens up a valve to let more oil thru so it'll go faster.
Going up a hill or putting a load it whines.
Also if on flat ground and have cruise set and then go uphill it slows down so I have to mash it more to go faster.

With a vari-belt drive I would think the speed would stay the same.
Does it?

What are the pros and cons of using each one?
 

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I've had nothing but bad experiences in the long-run with belt & variator pulley drive systems. My latest was on a cheapy, later model MTD rider with the MTD "Transmatic". The center (sliding) sheave on the variator pulley seizes up and you loose all but one ground speed. Minimal belt stretch also causes the same issue. I could never keep it in adjustment. Prior to that my family had a ~1970 JD 110 that was gear drive, but for what ever reason JD added a variator lever to more finely adjust ground speed if you wanted to. We learned to leave that lever full forward and not touch it. Inevitably, someone not familiar would use it and you'd have problems with that darn variable pulley. In short, go gear, hydrostatic or hydraulic (like on Case/Ingersoll) if you want long term reliability.

Joel
 

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A tractor with a hydro should always be run wide open throttle. The hydro will vary the speed by changing the angle on a swash plate which pumps more fluid, not with a valve.

If the hydro makes noise and slows on hills, it probably needs to be purged. It could also be tired oil and might benefit from an oil change.
 

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Discussion Starter #4
A tractor with a hydro should always be run wide open throttle. The hydro will vary the speed by changing the angle on a swash plate which pumps more fluid, not with a valve.

If the hydro makes noise and slows on hills, it probably needs to be purged. It could also be tired oil and might benefit from an oil change.
Just got it June 18th,if I'm mowing grass I have it full throttle,but if I'm just riding around the yard I may drop it to 1/2.
I have notice a louder whining at 1/2 throttle than at full but still pulling my aerator it still whines at full throttle.

Will it hurt it driving it at 1/2 throttle?
 

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The pump in the hydro needs full pressure to work properly,and you'll only get that,at full RPM..run the engine at 3000+ rpm and the hydro will work better and last longer..wont be as whiney either..
 

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The pump on a hydro will develop full pressure at any engine speed, but it will only develop full oil flow at full speed. The louder whine is the transmission working at closer to max pressure because it doesn't have sufficient oil flow to transmit the horsepower to do that part of the job.

Throttle up!

Bob :rauch10:
 

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Actually, the pump doesn't make pressure. That comes from the resistance to oil flow from the actuator (cylinder or motor) doing work. The pump just moves the oil at whatever pressure is required up to the relief valve setting, and even then it still moves the oil over the relief and makes lots of heat in the process.

Throttle up when you are working it and for hills. For just cruising around on the flat with the kids, part throttle is adequate.

Bob :rauch10:
 

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Still could need to be purged.
If he's been using it since June, it's purged. That's a one minute job of back and forth with the hydro. If any air has gotten into the system since then, there should be a puddle of oil on the ground where it's parked, unless it's low on oil in the first place. Then it won't run worth a darn.

Bob :rauch10:
 

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Discussion Starter #11
If he's been using it since June, it's purged. That's a one minute job of back and forth with the hydro. If any air has gotten into the system since then, there should be a puddle of oil on the ground where it's parked, unless it's low on oil in the first place. Then it won't run worth a darn.

Bob :rauch10:
When you say there would be oil on the ground,where would it leak from if it's a sealed unit?

I drove it around a little yesterday at full throttle and it seems to do good. My house has a basement and when I go from the back yard to the front up the little hill at full throttle it doesn't seem to slow down at all.
 

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That's the thing. If air can get in then oil can get out. As long as the intake for the pump is flooded, air can't get into the system unless there is a route from outside the 'sealed' unit. If there is such a route, it will show up as a leak. Depending on what part of the system contains that route, the leak may be large. Even a leak in the inlet side of the pump section will show as a damp spot on the case and the transmission will be very jerky.

Don't worry about it, air in the system is not the problem. Learning what throttle settings to use for different tasks takes time and experimentation. All hydros whine or growl to some extent, no matter where the throttle is set. They just get louder when you work them harder. Then it's time to either throttle up or ease off on the drive control, or both.

On the lighter hydros, more throttle is easier on the unit. I run my Husqvarna at 3/4 to full throttle except when parking it. My MF1655 runs at half throttle most of the time, even when working it pretty hard, but it has twice the tranny that my Husq has. Something like the difference between a pickup truck and a Peterbuilt.

Bob :rauch10:
 

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Every manual I have seen on hydro machines says to always operate at 3/4 to full throttle, I believe this is for cooling reasons.
 

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