Does HST Transmission Rob Horsepower??

[ptsg]

Probably because farms in Europe tend to be much smaller. When we visited in times past, it was common to see 10 acre farms. I bet youll see those features more and more on small tractors.
As the years go by in the US, so many Americans are fleeing the corruption of cities for lower taxed, simpler, less violent areas and go back to gardening & small time farming...

Exactly. Also, European manufacturers will offer stuff like compressed air and/or hydraulic brakes for trailers, along with ground speed sync'ed PTO also to power trailers, front diff locks, 3pt downforce ability, etc.

We do have some big farms as well. Mostly located towards the bottom half of Portugal. The upper half (North) of the country is very hilly, full of mountains and so on. The bottom half (South) is very very flat and nice for farms, so there is where the biggest farms are located.

I do know that they have two big JD 9620R with big scrappers attached to them, all fitted with laser stuff for grading. They mainly use these tractors to level big farms. Also, there are a lot of big Fendts, NH, Masseys, Valtra, JD, running down there.

We have huge tomato farms and when it's harvest time, the roads get packed with big tractors pulling fully loaded truck trailers using 5th wheel dolly's.

 

[Sno]

I spend quite a bit of time in close quarters, in soft ground, and on slippery hills. I’ve owned only gear drive and it seems my left and right foot are pretty well trained to act properly when things are difficult. I can certainly see advantages to an HST, but am concerned I just wouldn’t react properly when using one in difficult situations. I’m interested what others have found.

 

[MHarryE]

Here is an efficiency curve I had created by a hydrostatic system supplier when trying to resolve customer complaints that they needed to go faster than 4 mph (max speed at the max displacement of the propel motor) but the unit would not drive up slopes in high. This system introduced a variable control in the motor that varied the displacement depending on speed. What the graph really provides is the loss of efficiency of a hydro system throughout its range (this graph is at full system pressure 420 bar (about 6,100 psi). This is just the hydro system - following the motor there are gear reductions (just like in a hydro tractor) of which we figure 3% loss per gear set. In this cast it goes to a 40:1 gear reduction through a bevel gear and planetary so 6% additional loss due to the gears. In this case, the 107 HP engine will be putting about 77 HP to the ground not considering other parasitics (power steering, cooling fan, alternator). On the other hand, this machine (pneumatic tired roller for compacting asphalt) needs extremely smooth starts and stops to prevent ripping up hot asphalt and gears just don't cut it. The compromise is to sacrifice efficiency for performance. First prototype went to a crew that did have a mechanical transmission. They had converted the foot clutch to a hand clutch for the operator who had wore out his knee on the frequent shifts. It had a shuttle transmission but starts and stops were to abrupt so the operator needed to de-clutch at each end of a one minute pass. My Kubota L6060 would be similar to the green and blue curves - 2 motor displacements with no stepless shift.

 

[MiserableOldFart]

Tractor PTO is mechanical/gear all the way through.

Engine power transfer to the PTO will be the same whether tractor has a gear transmission or an HST transmission as PTO does not interface with the wheel transmission.


Engine power transferred to tractor wheels will be higher with a gear transmission.

HST is easier to use and speed choice infinite but it is pump/hydraulically driven, which is less efficient transferring energy than mechanical/gear drive.

Only a few tractor brands offer an HST transmission on tractors generating more than 60 engine horsepower. Over 60 engine horsepower most new tractors are available only with gear + shuttle shift.

HST and Gear/Shuttle are equally reliable.

HST and Gear/Shuttle are more reliable than traditional Gear/Clutch .

VIDEO:

Neal Messick, Messick's Tractor, ( five stores in Pennsylvania )
relates that Messick's sales are 90% HST in tractors of 60 horsepower or less.

All the data I have ever seen show Hydro versions of the same tractor having less PTO hp than gear. I would submit that it's likely that if that small amount of power is important to you, you probably should be looking for a more powerful tractor to begin with, but Hydro machines usually show lower PTO hp.

 

[ArlyA]

Same with UTV's that come with Hydro transmissions.

 

[Williy]

You could write a book on all the comments about which is better
a gear or hydro. The hydor's are being made more efficent and I
IMHO don't believe there is that much of a loss of power between
the two trannys. Just purchase what you like and be done with it.
Remember wanting what you have not wanting what you haven't
IS HAPPINESS!!!!
Maybe you young guys like shifting the gears as us old fogies like
the hyrto's as our knees and clutches don't get along so good.
Also for the price of the fuel it costs for the difference don't matter
cause we don't have a 1000 acres to work! So have fun with
what you have

willy

 

[npalen]

Which is better, a tractor with or without power steering? The tractor with power steering is going to have less power to the PTO. (or is it)

Edit: I ask this as a sort of rhetorical question as it somewhat parallels the issue of loss of PTO horsepower with HST verses GST.

 

[LD1]

Which is better, a tractor with or without power steering? The tractor with power steering is going to have less power to the PTO. (or is it)

Edit: I ask this as a sort of rhetorical question as it somewhat parallels the issue of loss of PTO horsepower with HST verses GST.

Or what about loading tires and adding a cab. Thats extra dead weight thats gonna rob power when going up hills?

 

[npalen]

Or what about loading tires and adding a cab. Thats extra dead weight thats gonna rob power when going up hills?

Yes, the point is that adding hydrostatic steering uses horsepower as the pump is running all the time but the benefit outweighs the cost. The difference in PTO horsepower rating on a hydrostat tractor is a somewhat confusing issue as many have alluded to in the above posts.

 

[Egon]

All the data I have ever seen show Hydro versions of the same tractor having less PTO hp than gear. I would submit that it's likely that if that small amount of power is important to you, you probably should be looking for a more powerful tractor to begin with, but Hydro machines usually show lower PTO hp.

The hst tractor will maintain engine rpm’s but slow down. The geared tractor will lose rpm, produce less HP to the PTO as well as slowing down.

These factors are incorporated into the electronic engine/transmission control.