HST vs. Gear

Dargo · Jan 9, 2006

( Hi,
I have a lot of hydro experience and now i've a shuttle shift transmission in my tractor. I love this for all kinds of work, even finish mowing work. After a time it will become very easy to drive with it, You don't realize it when you are shifting!!)

Yup, I thought the exact same with the shuttle until I tried the hydro. You are where I was about 3 years ago on this particular thought.

( A hydro in a larger tractor isn't a dream believe me you will lose a lot of power and torque only with the hydro.
A hydro is a good chose in little lawn mowers.
It depends of your work but when it is in first case mowing, you can consider to buy a hydro but don't go over the 30 hp limit.)

No disrespect, but this makes no sense. If you really think you lose so much power, why would you endorse a hydro for the tractors that can lease afford to lose any power; the smaller hp tractors? If your theory would be true, it would only make sense for you to endorse hydro transmissions in higher hp tractors, where a little power loss would not matter. You rather contradict yourself here.

( A manual tranny will be stronger as a hydro so after a time a hydro will cost more money. )

Really? And you found your research on this where? Everything I've read and experienced does not show this. I still like gear tractors, and really like shuttle shift tractors. So, I see no problems with people liking those tractors or buying those tractors. However, none of your arguements against hydro tractors are compelling in the least.

jinman · Jan 9, 2006

One of these days, some bright enterprising engineer is going to figure out a way to to give you gears and HST in the same tractor. Just think... with the flip of a lever you could go between gear drive and HST. /forums/images/graemlins/cool.gif

I know I'd pay at least a couple thousand extra just to have that feature, maybe more. /forums/images/graemlins/grin.gif

In the meantime, I'll love my HST when doing work on steep slopes or dirtwork with the FEL/Boxblade. When I'm in low/low and the transmission is stalled with the wheels sitting there while the engine revs, I'll just mutter some expletive about the pressure relief valves on the HST and keep wishing for that dual drive compact tractor of my dreams. /forums/images/graemlins/smile.gif

JerryG · Jan 9, 2006

One of these days, some bright enterprising engineer is going to figure out a way to to give you gears and HST in the same tractor. 
Actually that is just about what the CVT is in the MF, AGCO and what ever it is that JD calls theirs.

Large tractors don't have hydros because they are not fuel efficient. That is the reason that large tractors are power shifts or CVTs. To much fuel is converted to heat in hydros.

brewdog · Jan 9, 2006

I like Hydro, but I'd sure like to test drive an Ehydro and see what that is all about. I hate clutch problems too. Give me a new Hydro any day over shifting gears. Just my 2 cents.

wolc123 · Jan 9, 2006

I thought NHeuro had some valid points. I have owned many gear tractors and only one hydro (1972 12 hp cub cadet). That little hydro lawn mower sure was great but I can't imagine having one in my larger tractors which see a lot of field work. Most larger tractors are used with ground engaging equipment. Because this is a CUT forum, a good percentage of users have mowing as thier primary usage. Without question the hydro is superior at this task and probably loader work as well. If you want to see just how tough your 30 hp hydro CUT is, hook it to a 2-bottom 14" plow. My guess is that in hard ground it would take less than 100 hours to burn up the transmission. My 1951 gear 8n logged over 4000 hours on that job. Technically the power loss is a bigger deal on a smaller tractor. Let's get practical, hydro is more suited to small and gear to larger tractors for the reasons I have mentioned.

tposts · Jan 9, 2006

( That is the reason that large tractors are power shifts or CVTs. To much fuel is converted to heat in hydros. )
How come large dozers run hydro's ??? /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif

Dargo · Jan 9, 2006

( If you want to see just how tough your 30 hp hydro CUT is, hook it to a 2-bottom 14" plow. My guess is that in hard ground it would take less than 100 hours to burn up the transmission.)

Sorry, your "guess" is flat wrong. It's silly. Besides, my hydro tractor is 50 hp, not 30. I just happen to have a 2 bottom 16" Ferguson plow. What do you say, let's hook up your nice '51 tractor next to mine on a 110 degree day and plow away until one drops. I'll even spot you a few hp, I'll keep my A/C on. You up to it? I've done plenty more than that with hydro tractors. It's nice to know that your 1951 model worked fine for you. I simply opt for a more modern tractor with more hp; and a hydro. As you say, let's get practical, statistics simply show that you are wrong. Sorry.

As I said before, it would be a matter of personal choice. There is nothing wrong with gear, shuttle, or hydro tractors. Your assumptions are simply false about the lack of durability of hydro tractors. Do some searches. I think you can read steady for the next several years verifying that fact. In the mean while, I'll keep on verifying that fact on my tractor.

Soundguy · Jan 9, 2006

( Your assumptions are simply false about the lack of durability of hydro tractors. )

I'd wager to say that the hst tranny will plow fine.. but will not be as efficient getting hp to earth than a gear tranny.. but then.. I think that's been covered.

As for ultimate longevity? I'd have to say the jury is still out in my book on that. Untill I see some 50 year old hydros that run as good as many o fthe 50 year old gear trannies I have.. ( many with no leaks even.. ) then I'll reserve judgement. A few examples of the early non gear trans I've seen seem to work well.. but tend to be money pits for parts and service.. that experience is based on ford SOS trannies, and some older IH models... I know many gues adding progressively thicker oils to their ih trannies to get them to pull.. hoping to get another season out of them before they hand over 2x to 3x of the tractors worth in tranny rebuild.. vs buying a new tractor ( same on the fords by the way... not just picking on the ih... I'm a ford guy, and I really feel the ford SOS was the adam&eve of the POS auto style trannies... /forums/images/graemlins/grin.gif )

At least with a gear tranny.. if the seals catastrophically fail.. you just get a bad leak... the gears will still turn, without lube, if you just have to get it that last mile down the road.
I have to think that if an HST tranny suffered catastrophic seal failures... that it might just set there waiting for the roll-back truck /forums/images/graemlins/wink.gif and given that there are more 'soft' parts in an hst vs gear.. that makes me think that there are more chances for those failures.. etc...statistically. That is.. compairing a tranny with 2 seals vs one with 10 seals... Statistically I expect a higher percentage of failure ont he 2 seal job.. I.E. 50% or 100%.. but expect more seal failures innumber on the unit with more seals.. This includes orings, gaskets, etc... not just standard lip/cup seals.. etc..

Here's a question.. anyone know if a tractor with an HST tranny can be moved via starter in the same way that a gear tractor can? I'e' defeat the starter lockout, and energize the starter with clutch out and tractor in gear (very very very easy to do.. ) Will an HST function that way.. or will there be insuficient pump speed/pressure to get some motive force going? Reason i ask, is I have used that method, and have seent hat method used a couple times on gear tractors. one to load a non-starting tractor onto a trailer via battery/ starter and drivetrain. and another to move a tractor out of the middle of an intersection after stalling.....

Soundguy

YanmarFever · Jan 10, 2006

# 1 A hydro has to be reveed up all the time to work. therefore you use more fuel.

#2 A hydro is always at high rpm. therefore you use more engine life faster than at an idle.

Give me a Yanmar power shift any day over a gear or hydro !
They are bullet proof.

Just my .02, now go ahead & blast my opinions /forums/images/graemlins/smirk.gif

Ernie

jinman · Jan 10, 2006

( ...now go ahead & blast my opinions )

Now, how could I pass up such an invitation? /forums/images/graemlins/wink.gif /forums/images/graemlins/laugh.gif

( # 1 A hydro has to be reveed up all the time to work. therefore you use more fuel. )

I think that's an assumption. I don't believe any of us have done side-by-side comparisons between gear and HST trannies on the same model/size tractor. I'll grant you that it seems probable, but I'm not sure. What if I said I could get more loader work done quicker with a hydro? Could I say that fuel per yard of dirt moved would be the best measure? I'm just not sure how we measure productivity, but I have several RPMs that I use for different jobs. I seem to be able to work my tractor hard and use about 1/2 tank of fuel per day (6-1/2 gallons). I'm happy with that fuel consumption rate on a 45 hp tractor.

( #2 A hydro is always at high rpm. therefore you use more engine life faster than at an idle. )

Okay, Ernie...you said this.
How much work do you get done with your tractor at idle? If my tractor lasts forever, I want it to do more than just idle. /forums/images/graemlins/shocked.gif /forums/images/graemlins/smirk.gif

Okay, I'll quit being a wiseazz. /forums/images/graemlins/wink.gif I think there is a good chance that running at too low an rpm may be harder on an engine than running at higher rpm. I vary my engine speed between 1600 and 2600 rpm, depending on the job and what the work is. When I'm digging and filling my bucket with 1/2 yard of dirt, I'm likely to be at 2600 rpm. When I'm hauling a round bale, I'm closer to 1600. I just don't think the rpm issue is valid in the great Hydro vs. Gear debate. /forums/images/graemlins/smile.gif

Isn't your Yanmar power shift a gear transmission? Does it shift up and down in gears automatically or does it go between forward and reverse with the powershift? I think it's probably a very nice system, I just don't understand why you say it's not a gear or a hydro. /forums/images/graemlins/confused.gif

Some people say Ford's SOS transmission was not a gear transmission, but that is incorrect. The Select-O-Speed tranny was a gear transmission just like an automatic transmission on a car is a gear transmission. A car has a torque converter that makes it seem like fluid drive, but the planetary gears in the transmission are really just gears. Selection of those gears with servos and clutches is done automatically. On the Ford SOS transmission there was/is no torque converter. To shift, you use a lever that engages bands using hydraulic pressure, but the drivetrain is definitely gears. The SOS transmission is thus like an automatic transmission that has to be shifted manually and has no torque converter. There is no hydraulic motor being driven by a pump.