HST trans question

[2LMAKER]

Hello
I am starting to look at buying my first CUT. I am leaning towards HST trans but one question has come to mind. Does HST multiply the engine torque like a manual does? Even in automotive auto trans the torque converter does some multiplying.
Is this even important in a little tractor?
Thanks
Rob

 

[oldnslo]

Simple answer is yes. lower the ground speed the greater the torque to the drive wheels. Most models of CUT's also have two or three manual gear ranges you can select.

 

[WM75Guy]

My NH HST has a low/high speed range selector lever and a low/high speed button, also known as Turtle and Rabbit. The two in combination give you your choice of 4 different speed ranges. The pedals control the speed within the range selected, the more you push the pedal, the faster you go. Nothing in the operator's manual talks about the power available in each range, but is seems to be like a 4 wheel drive vehicle, low range Turtle has more power than high range Rabbit when digging with the FEL.

Probably more important than torque is the weight of the tractor. You can easily run out of traction before you run out of power. You sit there with the wheels spinning going nowhere. Loaded tires and a ballast box on the 3PH can help with this.

MY CVT transmission is a little different, it has three speed ranges, each a percentage of max speed. Low 0-30%, medium 0-60%, and high 0-100%. The more pedal the faster you go in that range. By selecting a lower range you get better pedal response. I usually run in low range which is 0-5 mph.

 

[Grandad4]

As noted, Rob, real tractors (not riding lawn mowers) are all about torque, weight, traction, pulling power and working power for attachments. A little sub-CUT may have the same "horsepower" as a single Sears lawnmower, but, in a pull-off, it would drag a herd of lawnmowers backwards. A compact tractor has all kinds of "low end torque" because of the gear reduction in the drivetrain. After all, it is specifically designed to do its work at slow speeds over uneven terrain.

It really doesn't matter whether it's a hydrostatic or a gear drive transmission; both put a lot of gear reduction between the rpm's of the engine and the drive wheels, and both have at least 2 ranges, sometimes 3.

 

[CompactTractorFan]

in a pull-off, it would drag a herd of lawnmowers backwards.

I never knew they traveled in "herds". :laughing:

 

[Damifino]

Well sure they do

 

[Grandad4]

I never knew they traveled in "herds". :laughing:

I suppose it depends on the brand; I was thinking of green at the time, but others might be in flocks, packs, litters, schools or who knows! :thumbsup:

 

[jenkinsph]

Granddad,

Had an issue with my X749 last week not starting and had to drag it backwards with my 4520. This was on a well packed gravel driveway and the 4520 is weighted with a total weight of about 5500lbs. The tractor would spin the tires pulling the lawnmower in two wheel drive, had to use 4x4 to drag the mower backwards. I was a little suprized about that.

 

[kday64]

I suppose it depends on the brand; I was thinking of green at the time, but others might be in flocks, packs, litters, schools or who knows! :thumbsup:

They could also move in prides or dazzles!

 

[Grandad4]

Granddad,

Had an issue with my X749 last week not starting and had to drag it backwards with my 4520. This was on a well packed gravel driveway and the 4520 is weighted with a total weight of about 5500lbs. The tractor would spin the tires pulling the lawnmower in two wheel drive, had to use 4x4 to drag the mower backwards. I was a little suprized about that.

At almost 3/4 of a ton, diesel engine, hydraulics, pto, etc., the X749 wasn't exactly what I had in mind! That's one really nice mower, though. So close to a sub-CUT, I'm not sure it shouldn't be called that.

I've also found reverse traction isn't quite the same as forward, whether in 2wd or 4wd.