HST Transmission

[yooperdave]

What are some of the bigger tractors which offer a HST style transmission?

It seems once you cross the line from a compact, you loose the HST option.

Thanks

Yooper Dave

 

[ZJ_HR]

Real tractors with stepless transmission starts at approx 100HP engine range.

FENDT Vario is pioneer in this technology, some years ago.
Now you can find that some other producers make stepless tranny, like Steyr CVT and JD IVT.
This system is more sophisticated than simple HST compacts, but results are similar.

Bigger combines had real hydrostatic drive long time before tractors.

ZJ

 

[slowrev]

I am not sure how many of the tractors mentioned have real hydrostatic trannys. CVT is not necessarially hydrostatic. It is often 2 variable diameter pulleys and a belt or somesuch in the middle. I have an old New Idea combine with a CVT tranny and it has NO hydraulics in the tranny, just variable pulleys.
I believe the main reason that large tractors don't have Hydro's is that they will not hold up as well under the really heavy loads, cost more to repair, loose more power, and generate a lot of heat. Remember an automatic transmission is not a Hydrostatic.

 

[jinman]

I don't know of any utility tractors over 50 hp that have hydrostatic, but I believe large loader backhoes like the New Holland LB75, Case 580s, and John Deere 310s have hydrostatic transmissions. All the ones I've rented (Case and NH) certainly seemed to be fluid drive and I think it was more than just a torque converter. I'm not an expert, but that was just my impression.

EDIT: Well it looks like I was wrong... again /forums/images/graemlins/blush.gif. New Holland's site says 4F/4R Power Reversing/Torque Converter for the LB75B.

 

[ZJ_HR]

Slowrew,

CVT on Steyr means Cotinous Variable Transmission, and it IS partially hydrostatic, similar to Vario, how is described url=http://www.fendt.com/seiten/Technik/getriebe_en.htm]here[/url] . This CVT only share name with belt variator, which one you described on your combine. BTW, on combine you have, is 2 or 3F+1R speed gearbox, and variator with V belt have just 1:3 or 1:5 ratio, when real Vario, or CVT or IVT have continuous speed from 0 to 50 km/h in both directions.

Your HST compact toys /forums/images/graemlins/grin.gif, sorry tractors /forums/images/graemlins/wink.gif, can't pull plough at full power whole day like CVT or geared tractors, and they are designed to be more practic for loader use (or am I wrong?).

Way of use on backhoes and small HST tractors are intermitent use, not continuous load like on farm tractors.

ZJ

 

[yooperdave]

I am looking for either the largest CUT or a 50 pto full size ag tractor. It is looking like a powerreverser option is in order for loader work.

Yooper Dave

 

[kensfarm]

I've pulled a 2 bottom plow for a couple of hours.. but not all day.. the TC35D handled it fine.. no heat problems.

If they made a "Big" Boomer in a 65-85 pto range w/ HST.. I'd be looking at that tractor for my next purchase.

 

[cowboydoc]

If go up to the JD 6?20 series you can get IVT transmission in the 80-100 plus "utility tractors". This isn't a hydrostat transmission but it works pretty much the same way. You don't have the forward and reverse like a hydro but you can infinitely control the speed. You can get the power reverser with this that will let you reverse with a simple flip of a lever.

I completely agree with you ZJ. The hydrostats are not designed to be used as a real ag tractor. Most of the owners of a cut are not going to be doing real farming with one anyway. Primarily they are for mowing, loader work, some backhoes, blade work, etc. Things that don't require alot of torque and bottom end power. That's not to say that hst won't plow occassionally but it's certainly not going to hold up like a gear tractor would.

Same reason you see hst in the backhoes and big loaders for construction equipment. They don't have a constant big load on the transmission like you would farming. It's stop and go, back and forth, and never really any constant load. Same with a bulldozer. You can have an hst in one because you are going to get the back and forth there as well. This gives the transmission a break and let's it cool down. That doesn't happen with a farm tractor that is hooked to a planter, ripper, disc, plow, etc. all day.

 

[equipman]

yooperdave
In the Kubota M series (utility tractors), there are now available hydraulic shuttle transmissions which allow for clutchless forward/ reverse shifting. Available on the M5700HD (52hp PTO) up to the M9000HD (80hp PTO). Hope this helps.
Lewis

 

[Old_Hickory]

What would be the 1st thing to go in a hydro ? What is the weak spot ? Would it be a heat related failure,or would it be stress related,fatigue etc ???