Does HST Transmission Rob Horsepower??

[clan scott]

-I heard from guys at work that the new tractors with HST transmissions rob the PTO of HP? What is the difference between HST and Shuttle Shift? Would like to buy a tractor to bush hog about 20+ years of brush overgrowth on 70 acres. I'm a fan of the FORD 10 series tractors but the new tractors seem inviting.

 

[lens12]

HST does require power. It uses a hydraulic pump to run a hydraulic motor. The shuttle shift usually uses gears with hydraulic clutches to engage & disengage gears which doesn't use as much power.

 

[jaydee325]

This discussion is really getting old.

Just determine how much PTO horsepower you need and buy a tractor, gear or hydrostatic with that much PTO horsepower.

 

[K5lwq]

For mowing I would prefer gear transmission. HST does not "rob" HP but uses HP just like any other thing on the tractor would. So yes there is less HP available for the mower.

 

[old and tired]

Agree with everyone else so far.... Just like the mower that is "robbing" HP, too... ALSO, this is NOT new... all HST (old and new) uses a certain amount of HP just like a 5 foot mower uses less HP than a 6 footer.

 

[jeff9366]

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.

 

[jeff9366]

Would like to buy a tractor to bush hog about 20+ years of brush overgrowth on 70 acres.

You will probably need a $10,000 to $12,000 Brown (brand) Tree Cutter weighing over one ton to cut trees twenty years old.

To power a 72" Brown Tree Cutter you will need a 80 to 100 engine horsepower, 4-WD tractor.

LINK: Brown Manufacturing Corporation - Brown Manufacturing Corp | 800.633.8909





March 2012:
clan scott

"I'm looking for feed back regarding the appropriate HP tractor I should have.

I will be purchasing a 76 acre old farm parcel and will be in the market for a tractor very soon. The land is grown over now for at least 9 years." (March 2012)

 

[ruffdog]

Will the OP be mowing a very open area or will it be trails or have many obstacles? Open field mowing go shuttle but if you have to maneuver around stuff, go HST.

 

[MossRoad]

This discussion is really getting old.

Just determine how much PTO horsepower you need and buy a tractor, gear or hydrostatic with that much PTO horsepower.

This is what most reasonable folks on TBN have been saying for 2 decades.

An HST does not "ROB" power. It uses power.

Yes, a gear tractor with a 30HP engine will deliver more power to the wheels than an HST tractor with a 30HP engine, due to efficiency losses in the transmission of power from the engine to the fluid and back to the rear end.

However, if you get an HST tractor that's spec'd to provide 30PTO HP, it will supply the same 30PTO HP that a geared tractor spec'd to provide 30PTO HP will. In order to do that, the HST tractor will probably have a few more engine HP to drive it at the same time the PTO is in operation.

It's really not that big of a concern on small tractors. Just get one that's rated to do the jobs you want to do and be happy.

 

[TractorGuy]

YES! Would I trade it for more PTO horsepower? Nope.