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

   / How does an HST compare in pulling power with the same tractor and a gear trans? #1  

sixdogs

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I just watched a video that compared results from two tractors. One with an HST; the other an 8 speed gear transmission. The results were a surprise in that the gear transmission seriously out-pulled the HST transmission in a tillage example. I could see the gear trans a little better but it seriously out-pulled the HST. The test was slightly flawed because of HST range selection issues so I'll ask here...

Has anyone had the chance to work the same--or similar-- tractor with an HST and then later a gear transmission and can offer a comparison of traction and pulling power? How does an HST compare with a gear trans in the same tractor? This would be in a tillage situation like pulling a disc harrow or cultivators on dry ground. Any thoughts on this?
 
   / How does an HST compare in pulling power with the same tractor and a gear trans? #2  

Jstpssng

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You're going to start up an age-long debate! Pulling power of an HST has never been a selling point. Ease of use for a lot of other applications is what makes them popular.

Or in my case, the geared tractor I wanted didn't have live PTO and I bought the used tractor available so that I could get some work done.
 
   / How does an HST compare in pulling power with the same tractor and a gear trans? #3  

K5lwq

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I would think with similar weight, traction and low range they would perform equally well. That said I have always preferred geared tractors. I have seen some of those videos and I believe they are not done very well.
 
   / How does an HST compare in pulling power with the same tractor and a gear trans? #5  

Jstpssng

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Naw...not the same horsepower delivered to the wheel on a hydrostatic. 10-15% of a hydrostatic’s power goes into making that whining noise.
:stirthepot:

Is that better? And you're probably 100% correct. ;)
 
   / How does an HST compare in pulling power with the same tractor and a gear trans? #6  

rademamj1

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HST transmissions have increasing inefficiencies the larger the HP ratings. Thus, almost all tractors 75Hp and higher are sold as geared tractors. They are the work horses of the Agriculture industry and their dominate field work is pulling. As horsepower increases, so does tractor weight.
 
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   / How does an HST compare in pulling power with the same tractor and a gear trans? #7  

4570Man

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If the goal was pulling a disk across a field hands down gears. But if you’ve bought a compact tractor to do that you’ve already screwed up. If the test was pulling a log out of the woods or pulling a vehicle out of the ditch the results will be close to identical. There’s gear lovers that won’t ever admit it but HST is better for practically every compact tractor task.
 
   / How does an HST compare in pulling power with the same tractor and a gear trans? #8  

buck12

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I have owned gear and HST. No idea how much HST costs at the wheels but for many the convenience of HST is worth the loss of power. I happen to me one those who will gladly give up a little HP for the convenience.
 
   / How does an HST compare in pulling power with the same tractor and a gear trans? #9  

k0ua

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Hm.. I always thought the deciding factor that determined how much drawbar pull a tractor had was the type of tires and whether they were correct for the pulling job at hand to "hook up" to the surface they were suitable for AND the weight on those tires.

With the more weight on those tires determining if the tires would lose traction with the surface and spin or would deliver all available torque the engine would provide. Of course factoring into this is the tractor in the proper gear for the attempted pull, and hopefully some moron did not put a hydrostatic transmission in too high of a gear range so that the hydro relief valve did not open and thus prevent the maximum power to be delivered to the hydraulic motor. Of course the same could be said if the moron put the gear tractor in too high of a gear and stalled the engine. But again the biggest determining factor is tractor weight, with heavier tractors "outpulling" lighter tractors each and every time as long as their gearing is such to not stall the engines or open the relieve valve and as long as their tires "hook up"

These types of questions have only one answer: "it depends" It is kinda like asking which pickup pulls harder, Chevy, Ford, or Dodge. Well it depends. And it depends on dozens of factors.

Let me ask you a question: What difference in "pulling power" (and first we would have to define what that means to you) would the fact that a hydrostatic transmission loses about 15 percent of the energy going into the hydraulic pump from the engine and between the output shaft of the hydraulic motor IF the hydrostat equipped tractor can and does spin its tires when pulling against an immovable object. So if the gear transmission tractor spins it tires too, what does that tell you? It tells me that more drawbar pull could have been achieved if both tractors had the correct tires fitted for the job and both tractors had sufficient weight added so that the tires would not spin up to the point that the engines stopped or the relief valve opened. But when someone comes along and makes a misleading video to "stir the pot" and stir up FUD what can we say?

Now I suppose It might be possible to cause a hydro transmission tractor to open the relief valve in Low range, I have never seen it and I have owned 3 hydro tractors. Mine have always spun the tires even with loaded tires and a heavy ballast on the 3pth. Of course I have usually had R4 tires too. Perhaps If the test was in soil and I had R1 tires, perhaps the tires would not have spun and perhaps the relief valve would have opened.
 
   / How does an HST compare in pulling power with the same tractor and a gear trans? #10  

ptsg

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If the goal was pulling a disk across a field hands down gears. But if you致e bought a compact tractor to do that you致e already screwed up. If the test was pulling a log out of the woods or pulling a vehicle out of the ditch the results will be close to identical. There痴 gear lovers that won稚 ever admit it but HST is better for practically every compact tractor task.

Except in countries where tractors with 50HP and lower are used to make a living on farming, logging or even land clearing, but this may also be the reason on why HST tractors have to be special ordered on this side of the pond.

Another point to consider is that tractors are drove on the road a lot and won't have to fully stop and change ranges on a slight hill. Just a simple gear downshift on the move and you're good to go.

Kioti DK5010 pulling some sticks for reference:

107936787_2717602271810325_1726853769495266960_n.jpg 106923650_2709561835947702_7148501979511862537_n.jpg
 
 
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