Hydro Static Transmissions ??

Mark Page · Mar 3, 2012

Do all HST's work the same way? Does the engine speed change as you press the pedal. Or does it work like a geared machine where you set the throttle and go from there.
It would seem necessary for the engine to be able to keep up with transmission's demands or it would feeel real doggy.
My JD rider works from a constant engine speed, as you depresss the pedal it goes forward with no change in engine speed.

TripleR · Mar 3, 2012

The Kubota HST+ has an "auto throttle" you can set to increase engine speed as you press on the HST pedal, I don't know if other manufacturers have this or not.

http://www.messicks.com/Articles/KubotaHSTplus.aspx

k0ua · Mar 3, 2012

I am pretty sure the e-hydro John Deere also works that way too, but my L3400HST does not vary the engine speed. You must set the hand throttle (there is no foot throttle) to the expected load. While you can dog around at 1000 rpm (usefull when hooking up 3pt) when you are working you will want to be above 1500 for most jobs. The only annoyance is when you stop then the engine is still turning pretty fast and you have to chop the throttle by hand. With the grand L machines this is all automatic. and it will also adjust the swashplate to in essence give lower "gearing" when the load on the system changes. But with the simpler machines like mine is is all about you.

James K0UA

k0ua · Mar 3, 2012

Everything you wanted to know about HST+ but were afraid to ask

[ame=http://www.youtube.com/watch?v=hzO_-LCd838]Kubota HST-Plus Transmission - YouTube[/ame]

James K0UA

jenkinsph · Mar 3, 2012

The auto throttle is an option available for most Deere machines with ehydro. I find it to be a good option and use it all the time on my 4520.

GPintheMitten · Mar 3, 2012

Mark Page said:
Do all HST's work the same way? Does the engine speed change as you press the pedal. Or does it work like a geared machine where you set the throttle and go from there.
It would seem necessary for the engine to be able to keep up with transmission's demands or it would feeel real doggy.
My JD rider works from a constant engine speed, as you depresss the pedal it goes forward with no change in engine speed.

The "standard" HST works as you describe. You adjust the engine speed separately from the ground speed. That's one of the benefits to HST. You can go as slow as you want and keep the engine rpm's up as necessary to get the power to the pto.

32 chev · Mar 3, 2012

My MF 1531 will work either way

George2615 · Mar 3, 2012

My Mahindra has a manual hand lever to set engine RPM (no foot throttle). Speed is then variable using the HST pedal.

massy1635 · Mar 3, 2012

My Massey 1635 works both ways.

Brimstone10x · Mar 3, 2012

Im thinking Mark dosent know what a swash plate is , if he did he would already know how a hydro works.

k0ua · Mar 3, 2012

Brimstone10x said:
Im thinking Mark dosent know what a swash plate is , if he did he would already know how a hydro works.

Point taken

GPintheMitten · Mar 3, 2012

Brimstone10x said:
Im thinking Mark dosent know what a swash plate is , if he did he would already know how a hydro works.

I'm trying to figure out your point. The man asked a question to get an answer. Are you making fun of him? Maybe not, but it seems like it. By the way, I don't know what a swatch plate is either.

whistlepig · Mar 3, 2012

Mark Page said:
Do all HST's work the same way? Does the engine speed change as you press the pedal. Or does it work like a geared machine where you set the throttle and go from there.
It would seem necessary for the engine to be able to keep up with transmission's demands or it would feeel real doggy.
My JD rider works from a constant engine speed, as you depresss the pedal it goes forward with no change in engine speed.

I have an older HST. 2006 it is. Engine speed is constant and no auto throttle. I just feather the 'go" peddle on the HST. This works extremely well. I am kind of wondering what are the advantages of auto throttle myself.

k0ua · Mar 3, 2012

whistlepig said:
I have an older HST. 2006 it is. Engine speed is constant and no auto throttle. I just feather the 'go" peddle on the HST. This works extremely well. I am kind of wondering what are the advantages of auto throttle myself.

Whistlepig, you know how when you stop the tractor the first thing you do is chop the throttle to get rid of the noise and reduce fuel consumption? well the autothrottle does that for you. And when you step on the hydro pedal, it rev's up and you go.. I just keeps you from having to mess with the hand throttle.

James K0UA

k0ua · Mar 3, 2012

GPintheMitten said:
I'm trying to figure out your point. The man asked a question to get an answer. Are you making fun of him? Maybe not, but it seems like it. By the way, I don't know what a swatch plate is either.

Maybe this will help a little.. the swash plate is the movable tilting plate the pedal controls and the pistons are engaging.. For you helicopter mechanics you will be familiar with a similar swash plate to control the rotor. I do not have a great understanding of the subject either, but I have the general idea.

[ame=http://www.youtube.com/watch?v=BQy_rLrMmJQ]Hydraulics_How a hydraulic transmission piston pump works - YouTube[/ame]

James K0UA

arrow · Mar 3, 2012

k0ua said:
Everything you wanted to know about HST+ but were afraid to ask

Kubota HST-Plus Transmission - YouTube

James K0UA

Huh?. After seeing this video a better title for me would have been: "Everything you wanted to know about HST but were afraid to ask but once you knew, more afraid to own" So this is the kind of tractor digital savvy people like to buy. This would make me nuts.

Martian · Mar 3, 2012

The Kubota HST+ is really nice. Most advanced hydro on the market. I don't know if I'm sold on it, I'm one who likes a little simplicity, but I hear the features are great.

I can say, switching between gear and the 'basic' hydro trannies it makes you stop and think. When I got my first hydro tractor, the 3120 it was a big learning curve. On the gears, when you need more power you press the pedal and you have to depress the pedal on the hydro. I'm still a big fan of the hydros and gears though. Each have their respectful place in the market.

k0ua · Mar 3, 2012

arrow said:
Huh?. After seeing this video a better title for me would have been: "Everything you wanted to know about HST but were afraid to ask but once you knew, more afraid to own" So this is the kind of tractor digital savvy people like to buy. This would make me nuts.

Well that is why they make so many different models.. Mine is just a simple hydrostat. Just a pedal you rock forwards and backwards.. No electronics. But I sure would like to try some of those neat features of the HST+. I have never heard one discourging word about HST+.. I think most of the people that have them like them.. Yes I am digital (and IP too!) savvy..

James K0UA

MHarryE · Mar 3, 2012

Kubota's HST Plus isn't that much of an electronic gizmo. There is a mechanical link from the pedal to the injection pump so as you speed up it mechanically increases engine speed, but you can set the low engine speed with the regular engine speed lever (I avoid calling it a throttle because a diesel doesn't really have a throttle like a carburetor) so when you stop the engine speed doesn't drop too low. On mine if I don't set it to about 2000 rpm minimum when doing loader wrk the loader gets real sluggish when you stop to dump and the engine slows to low idle. The best feature for me is the 2 speed hydro motor that shifts automatically to a steeper swash plate angle when the engine pulls down. It is like an automatic shift down but it also gives the advantage of higher hydraulic efficiency at the steeper swashplate angle. In a tough pull mine will pull better in 2nd gear low range than in first gear high range. I have a graph of the motor and it really loses efficiency at flat swashplate angle high hydro pressure.

Don87 · Mar 4, 2012

arrow said:
Huh?. After seeing this video a better title for me would have been: "Everything you wanted to know about HST but were afraid to ask but once you knew, more afraid to own" So this is the kind of tractor digital savvy people like to buy. This would make me nuts.

You are here with us, comparing helicopters to kubota trannys..............maybe, just maybe............you is nuts:shocked::shocked::laughing::laughing:

But maybe ifn' you trade in that JD750 for the 'Bota............you can fly over and visit some folks

EDIT: This was too easy............I couldn't resist. Please forgive me.