Why no hydrostatic transmissions on larger tractors?

[5030]

I guess I should've said "someone with dealer support near me". Fendt certainly makes some incredible stuff but ive never even seen one in person locally.

There is a Fendt dealer in Ionia, Michigan on M66, just south of town if you want to see them.... Got a sign out front 'Big wallets Only'...lol (just kidding).

 

[Bob Rooks]

It's an evolutionary process. Remember when you couldn't buy a car with an automatic transmission? Now you can't buy a car without one. Even tractor shuttle clutch "reversers" are a fairly recent development in the tractor chronology. Popularity/demand is fueled by price-point, convenience, ease of use, reliability, and demographic. It's only a matter of time before HST tractors of any horsepower will be the norm. Cite the Liebherr PR776 dozer. However, this progress is being somewhat overshadowed by the advancement of e-tractors. This all is assuming we don't blow ourselves up first.

 

[WranglerX]

 

[barts]

Note that diesel locomotives started out with geared and hydraulic transmissions; they're all diesel-electric now as are really large earth moving equipment, ferry boats, etc. Technology changes over time and trade-offs vary w/ different sizes and uses. Cargo ships use direct drive, because they operate at a designed speed most of the time. Ferries here in the Pacific Northwest do a lot of docking, and are double-ended; diesel electric drives are a natural. Tractors see very different uses, from frequent forward-reverse w/ a FEL or snow blade to plowing at a steady speed to mowing, pulling trailers, etc. Note that higher hp tractors are typically used at more constant speeds, and the efficiency penalties become really significant for little practical gain.

 

[Sawyer Rob]

Meanwhile, my Payloader has 13,000 hours on its "unreliable" hydraulic transmission. It is on its second D466, arguably the most reliable mid-size, straight-six diesel produced.

As soon as they "figure out" how to put THAT Payloader hydraulic transmission in a tinkertoy tractor, they will have figured out how to "up" the reliability.

SR

 

[JWR]

Late comment, different perspective: It depends on the size, power and applications intended for the tractor as many have said. Narrowing to the smaller tractors, well under 100hp, there are several things to consider -- how many ranges for the HST?

One scenario: In the small 20 some hp machines 2 range is common. You dare not start down a steep river bank expecting to back up at a crucial point (in 4WD where you have plenty of traction) in high range because it will sit there and hum rather than get you back up the bank and the #$%^ brakes are worthless (removing your ability to shift to low range). Yes I mean BX2200 and similar.

Another scenario: 25 to 45hp or so, 3 ranges. The 3 ranges make a huge difference and can be tolerated, even sometimes an advantage, esp. if doing a lot of loader work. I can see many machines in this size/hp being attractive as hydros.

Another: 50 to 90hp or so -- If I go in and out of steep gullies and 50% grades wanting to hold the tractor, ease it down, etc. while bush hogging (or operating a boom cutter in less steep spots) I do not want any part of a hydrostatic machine. Gears mean definite contact. Hydro means maybe. Not for me.

It does not totally apply across the board, but I've seen an automatic tranny motor home get stuck in mud and with the accelerator floored it sits there and hums. I've seen small 4wd lawn machines put me in danger trying to get back up a creek bank -- sits there and hums. With a stick you can at least spin tires and cause them to turn when you need to.

If I ever replace my 81HP 4wd utility tractor I guarantee you it will not be with something that might "sit there and hum."

 

[jdmeth]

I opine that the larger power, the more difficult it is to get the engine out through an HST to the wheels. I had a 14HP JD650, manual transmission. It had lots of umpf (for a small tractor), you could certainty stall it pushing or pulling too hard. I replaced it with a 25HP JD1025R. It does not have the [mini] brute force that the JD650 did. When you work it too hard, it makes really unpleasant noises which the engine turns and the wheels don't - so I stop doing that. But the 650 would either have moved the load, spun the wheels, or stalled. So I opine that the tractor manufacturers know this, and don't build bigger tractors which won't pull a heavy load well.

I have a JD 1023E which is basically the same as the 1025R. In low range the wheels will spin, if you have a hard pull or are trying to load the FEL bucket slip it into low range.

 

[GB540]

International tried it in the 1970's, and they weren't the answer for the reasons others mentioned: loud, ran hot, and didn't pull well under load.

Now, had IH took a different route, they had the ingredients for what we now call IVT. Hindsight 20/20.

 

[npalen]

International tried it in the 1970's, and they weren't the answer for the reasons others mentioned: loud, ran hot, and didn't pull well under load.

Now, had IH took a different route, they had the ingredients for what we now call IVT. Hindsight 20/20.

But they make excellent FEL tractors, right?

 

[npalen]

I'm hearing the Payloaders referred to hydraulic drive but were they not actually torque converter drive? I suppose they would be hydraulic in the true sense of the word but not hydraulic as we normally think of it.