Does HST Transmission Rob Horsepower??

[Egon]

With the ability of an HST to modulate ground speed at a set engine RMP it may get by with a smaller engine than a fixed gear transmission.

 

[jeff9366]

Gears are maybe less prone to 'go wrong' (as my thrifty relatives would say) versus the 'more complicated' HST. I have both.

If comparing Gear/Shuttle to HST reliability is about the same. Gear/Shuttle will yield better fuel economy, which is important to 'big ag".

In Gear/Clutch combination the traditional clutch, not the gears, is the weak point. And that is the reason few subcompact tractors are offered with a Gear/Clutch option.

Clutch rebuilds at my local Florida Kubota dealer are $1,200. Clutch rebuilds are probably $2,000 in New York or Western Washington. Clutch rebuilds are NOT warranty repairs.

Anyone buying a Gear/Clutch tractor for operation by employees is making a bad decision. The clutch will be abused and employees will run the FEL into immovable objects regularly.

 

[ptsg]

If comparing Gear/Shuttle to HST reliability is about the same. Gear/Shuttle will yield better fuel economy, which is important to 'big ag".

In Gear/Clutch combination the traditional clutch, not the gears, is the weak point. And that is the reason few subcompact tractors are offered with a Gear/Clutch option.

Clutch rebuilds at my local Florida Kubota dealer are $1,200. Clutch rebuilds are probably $2,000 in New York or Western Washington. Clutch rebuilds are NOT warranty repairs.

Anyone buying a Gear/Clutch tractor for operation by employees is making a bad decision. The clutch will be abused and employees will run the FEL into immovable objects regularly.

Seriously, how do you come up with this stuff?? I just can't get it.

"In Gear/Clutch combination the traditional clutch, not the gears, is the weak point. And that is the reason few subcompact tractors are offered with a Gear/Clutch option." - No, this is not the reason why SCUTs are offered mainly with HST. The reason is most likely due to the fact that most SCUT and CUTs owners, use their tractors to mow the lawn and/or move snow around, plus all that some can drive is automatic transmissions and can't handle a clutch at all. Definitely not because the clutch is the weakest link. The operator yes, can make a clutch look like the weakest link.

On this side of the pond, it's very common hear clutches lasting over 4 or 5k hours, easily. Some a lot more, but then again, probably 95%+ of the vehicles are manual transmission. So it's not a big deal at all to use a clutch, even on loader tractors.

Also, tractors from 15HP and up are using hard on farming for a living by most people who owns tractors. Tasks like plowing a field, disking, using rippers, etc. Pretty much tasks that would make an hydrostatic transmission cry.

 

[ArlyA]

15hp and up for the agricultural business?? I'm guessing the farms in Europe, might be a tad smaller than those in north America. Most of my family are in the AG business.

 

[ptsg]

15hp and up for the agricultural business?? I'm guessing the farms in Europe, might be a tad smaller than those in north America. Most of my family are in the AG business.

A small tractor can fit places where a big one can't. If you don't believe, go search a little bit about farming in Europe.

Also, small tractors can farm too. Very common for people that sell at the local market to have a small 15 to 30 tractor that can easily fit inside a small greenhouse or small plots.

 

[ArlyA]

A small tractor can fit places where a big one can't. If you don't believe, go search a little bit about farming in Europe.

Also, small tractors can farm too. Very common for people that sell at the local market to have a small 15 to 30 tractor that can easily fit inside a small greenhouse or small plots.

Of course I know the farms there tend to be smaller. I am not disparaging European farming at all, they have different geology, soils, history, what they grow and everything else make it different, not necessarily bad or good. Here is a video of harvesting winter wheat very near where my family operate there farms. Its very different than there, not better or poorer. Would anyone care to guess the HP of the tractor towing the grain cart has??

 

[old and tired]

Would anyone care to guess the HP of the tractor towing the grain cart has??

335 HP....

 

[Hay Dude]

Drawbar Horsepower is different between gear & HST
Make sure when you buy a tractor, whether its HST, gear, powershift, IVT, CVT; toss the manufacturers specs aside and find independent tests, like Nebraska tests/Tractor Data tests or even ask the dealer to do a dyno test if he has one.
For example, my MX-270 is factory rated to make 235 PTO HP and 270 engine HP.
Tractor data tests show 271 PTO HP. My own dyno test was 270, which leads me to believe the 8.3L Cummins is making over 300HP.

Some tractors will test lower than claimed, some higher.

 

[wolc123]

Compared to gear drive, a hydro drive transmission converts a higher percentage of an engine's hp to heat. That heat energy is not useful to get work done. If you are looking to get the most work done, per gallon of fuel, then a gear drive is the best option.

So the answer to the op question is YES, a hydro robs hp because it converts more of it into a useless form (heat), than does a gear drive.

That said, I am willing to be robbed a little bit for smaller jobs because my time is worth more to me than a few gallons of fuel. I much prefer mowing my 1 acre lawn with my 15 hydro tractor than my 15 hp gear tractor. I only use that gear tractor in times of frequent rains, when the grass grows too thick and overpowers my 15 hp hydro. At those times, the hydro bogs down and I can get the job done faster with the gear.

For big jobs, like open field mowing, I would not dream of using a hydro transmission.

 

[Hay Dude]

The price you pay for convenience