dumb question about HST

[phantom309]

Hi TYM/Branson gurus.

A friend of mine is making some progress convincing me to give HST a try on next tractor. No doubt HST is a LOT better at the back and forth, but in some applications, it is not quite as good (for example: large, open field mowing).

I'm having trouble doing the math to see if a large gain seen very seldom is worth a tiny loss on my bread and butter task.

One question: I've read that HST tractors lose more HP to the PTO than gear drive. Why is that? Is the PTO driven by pump or by gears? I would have guessed that even on HST tractors, the PTO was still gear driven. No?

 

[mjonesnh]

Hi TYM/Branson gurus.

A friend of mine is making some progress convincing me to give HST a try on next tractor. No doubt HST is a LOT better at the back and forth, but in some applications, it is not quite as good (for example: large, open field mowing).

I'm having trouble doing the math to see if a large gain seen very seldom is worth a tiny loss on my bread and butter task.

One question: I've read that HST tractors lose more HP to the PTO than gear drive. Why is that? Is the PTO driven by pump or by gears? I would have guessed that even on HST tractors, the PTO was still gear driven. No?

Cannot comment on TYM but have a New Holland. The PTO on my TC34DA is gear driven with a clutch to engage and disengage. Engine HP is rated 35HP with 28.9 at PTO. Have seen some HST models with larger HP loss to PTO.

 

[Torvy]

All brands that have HST and Gear versions have less HP at the PTO on the HST. Some of the HP is taken up operating the transmission (how I understand it).

The mowing 'problem' is overstated. You can set cruise on an HST for long mowing stretches.

The only things that really matter are for ground engagement or something where you are close to the HP minimum for the PTO attachment. I solved that by spending an extra $1500 for the turbo version.

I was initially going to get gear drive, but after test driving them both, the HST was just too good to pass up. In my case the price for HST or gear was the same. Some brands it costs more.

 

[JJT]

My 40 hp HST will keep up with my neighbors 60 hp geared tractor, and we both run 6' mowers. If I get into heavy stuff or need to pull a a hill I don't have to shift, he loses lots of time shifting gears.

 

[dodge man]

I had never run a gear tractor until a few months ago. It wasn’t bad to run at all. I think for most homeowners an hst is better, myself included but there is nothing wrong with a gear tractor either.

 

[oldnslo]

HST loses power due to charge pump being 100% power loss and heat generation along with a little more splash frictional loss.

Main use where HST is potentially less desirable is steady full draw bar pull like plowing a field.

Doing PTO work doubt you will even notice the difference

 

[LouNY]

My 40 hp HST will keep up with my neighbors 60 hp geared tractor, and we both run 6' mowers. If I get into heavy stuff or need to pull a a hill I don't have to shift, he loses lots of time shifting gears.

Interesting, I would have expected the gear unit do do much better.

 

[4570Man]

I’d put my money on the HST for winning at mowing the vast majority of the time. The HST doesn’t actually loose much power unless the transmission is working hard. Driving across a field isn’t working the transmission very hard. The HST can travel at exactly the speed the mowing conditions allow. That’s less of a difference if you had 12 or 16 gears but the cheaper tractors that just have maybe 8 gears are always going the wrong speed. The HST is also easier to slow down for a rough spot or a turn and then speed back up again. Most HSTs also have a cruise control.

 

[Sawyer Rob]

Interesting, I would have expected the gear unit do do much better.

Lou, there are so many unknown variables in his test, it would be easy to sway it either way for the win.

I can get things done faster than my neighbor, even though his tractor is bigger with more pto HP, even doing the same jobs side by side, like mowing. Does that mean MY tractor is better for those jobs and has more power?

I'm sure you know the answer to that question.

SR

 

[Sawyer Rob]

Here's the main reasons I didn't buy a hystat last time around.

1. My gear drive cost me a LOT less than the same model with the whiner tranny.
2. I can't stand listening to the whine of those whiner trannys!
3. it cost a LOT less for maintenance on a gear drive, a LOT less!
4. gear drive puts out LESS heat and MORE pto HP
5. I like to throttle back and not have to listen to the engine spinning fast, even when pulling loads, I can regulate my speed just fine with the foot throttle pedal.
6. gear drive use LESS fuel, especially because I can keep the rpm down.

I could go on and on, but there's 6 really good reasons right there.

BTW, I prefer to get a tractor with creep gears too, in case you want to buy a stump grinder. (I MUCH prefer a gear drive for stump grinding too)

SR