How does an HST compare in pulling power with the same tractor and a gear trans?

[Industrial Toys]

Why would the geared model out pull the hydros and day of the week? Were they hydro or torque converter transmissions? In a sense it's like asking if the same truck can pull more in gear or auto transmission versions.

 

[4570Man]

Why would the geared model out pull the hydros and day of the week? Were they hydro or torque converter transmissions? In a sense it's like asking if the same truck can pull more in gear or auto transmission versions.

They’ll pull a load faster but the max drawbar pull is about the same.

 

[Industrial Toys]

Is a hydro model heavier on the rear wheels?

 

[CobyRupert]

From some people who know more than me:
“A discrete-gear transmission will typically have an efficiency of 95% or greater, meaning that 95% of the input energy is delivered to the load (wheels). A hydrostatic transmission has an efficiency of around 80%. Some well designed units will have an efficiency slightly above 85%, but none can approach the efficiency of a discrete-gear transmission. A designer always poses the question: Does the gain in vehicle productivity offset the loss in efficiency and resultant higher fuel cost?”

Hydrostatic Transmissions Advantages | Hydraulic Pump

 

[Industrial Toys]

I guess as tractors for field work get bigger quickly, those losses become unacceptable. Also the extra heat. And noise?

 

[3gunr]

I used a 33 HP NH and LS that are virtually the same.

I tested both in a mid range gear that put them at equal speed. The HST would bog down and stop when working up steep hills. The gear didn't even notice the hill and could almost idle up it.

They are both have the same max pull force in low range as they are traction limited, even on flat concrete.

HST will do the same work, just slower than gear.

I still bought HST since I don't have enough hands and feet to: steer, shift, brake, clutch, operate loader, change throttle while navigating my constantly changing terrain.

I have mowed tall grass and brush up a steep hill with a 6 ft cutter behind a 32 pto hp hst mahindra without the slightest bog.In fact i have dug tons of dirt out of a tall bank and never came close to it bogging way down.

 

[Industrial Toys]

FWIW, I guess a lot of Dozers now have hydrostat transmissions. That kind of says something about how good they are at managing power. Despite ineficiencies.

 

[rademamj1]

Not trying to change the subject, but I just had a long discussion about this thread with a neighbor, and he brought up the subject that skid steer HST systems are powerful and smooth well into the 95HP range. Something I not familiar with. But I cannot find a single specification on any Skid Steer HST transmissions.

 

[K5lwq]

I don't think a skid steer has a transmission like a HST tractor. They use a pump that drives individual motors to drive the wheels. Similar to a zero turn mower. This gives the flexibility to have one motor going one direction while the other motor goes the other direction.

I do think this thread is a lot more informative than what I thought it would be. Good conversations.

 

[Industrial Toys]

You are correct. Just a pump and the operator controls the flow of oil (manually or by electronic means) to the hydraulic motors, one on each side.