dumb question about HST

[skid mark]

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

 

[CloverKnollFarms]

HST is great for mowing. Infinite speed selection. They all have cruise control now, so I set my speed, set the cruise, and take my foot off the pedal.

 

[Torvy]

Dad used to tell a joke about cruise control. I'll butcher it...

Nack during the war, an Aussie pilot and an American pilot were on R&R in Japan. They decide to go for a drive up Mt. Fuji. American starts driving and the Aussie asks him about the cruise control. "It's like auto-pilot for the car", says the Yank. A few hours later, they switch drivers. The Aussie decides to give it a go. He sets the cruise, leans back and goes to sleep.

(No real pilots were harmed in the writing of this joke. No offense toward Aussies, Yanks, or pilots should be inferred.)

 

[jyoutz]

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.

A great feature of HST machines is that ground speed can be varied while maintaining pto/engine rpm. A gear tractor must be shifted to do the same.

 

[K5lwq]

This debate never gets old.

I am in the gear camp. I never have found myself changing gears a lot or wishing for more gear options.

But one time I was out of town working a lot and knew when I got home the grass would be 2ft tall. But as I pulled into the driveway everything was mowed nicely. My dad decided to come mow for me.

He said the next tractor I get needs to be a HST. I asked him why and he said low 3rd is too slow and high 1st is too fast. I said I never had that problem but I use low 4th. He said that he didn’t realize my Kioti had 8 gears.

 

[skid mark]

Thanks for the many informative replies.

Good to read that HST tractors do in fact use gears to drive PTO.

The lower PTO rating for HST not being due to how the PTO is driven, but instead is the result of the increased overhead of HST makes sense, but I hadn't thought of that.

Of course there are some high HP stationary PTO implements that are run with range selector in 'N' (and foot off of HST pedals). I guess that in that case, HP would be the same between gear and HST.

 

[skid mark]

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

Thanks for your reply SR.

Your last comment about creep gears and stump grinding caught my eye. I've been wondering about that very thing.

I have two geared tractors (both 8-speeds), and although I've never used a PTO powered stump grinder, I would guess that low range, low gear in my tractors isn't quite enough of a creep to run a "pull behind" stump grinder (without a lot of clutch work).

I do plan to purchase a stump grinder with next tractor purchase and the "pull behind" would save me a few $$$ over the "hydraulic swing" if it would work.

If I go with another geared tractor, I'm leaning towards TYM/Branson 5520R (16 speed!) or 5835 (12 speed).

Wondering if either of those tractors can move slowly enough in low gear to use the "pull behind" stump grinder?

 

[DC61]

I have a TYM T654. 24 forward and 24 reverse gears. In creep it will run at 1/4 mile an hour at 540 pto speed/RPM. I don't have a stump grinder but I think it would handle on no problem. The only time I ever run in creep is when hooking up to implements. It's a clutch tractor mostly used for plowing, discing and pulling a bat wing shredder.

 

[Mtsoxfan]

One feature my new Kioti has is a linked pedal. Just like driving a car, when you press forward pedal, the RPM respond in kind. I can unlink when using the PTO to keep RPM at proper speed.

 

[CloverKnollFarms]

My Branson has a linked pedal too. It cannot be disconnected, but you can set the hand throttle at whatever minimum RPM you want, so that when you let off the pedal, it sustains it. So I'll set it at whatever I want as a minimum, and override it with the pedal if need be

 

[LouNY]

Thanks for the many informative replies.

Good to read that HST tractors do in fact use gears to drive PTO.

The lower PTO rating for HST not being due to how the PTO is driven, but instead is the result of the increased overhead of HST makes sense, but I hadn't thought of that.

Of course there are some high HP stationary PTO implements that are run with range selector in 'N' (and foot off of HST pedals). I guess that in that case, HP would be the same between gear and HST.

Nope you still have the power loss as the hydrostatic pump and motor is still spinning.