Does HST Transmission Rob Horsepower??

[RancherGuy]

I have to respectfully disagree with many of the HST comments here. It seems that those who quote the advantages have not experienced the disadvantages, or perhaps they have seen or ridden on someone else's, or they think that HST on a lawnmower is the same as on a tractor.

Do HST consume more power than geared? Absolutely. So a bigger engine is required to get the same work done.

What impact does HST have on PTO power? Depends. If you are the manufacturer, you will do a PTO test with the tractor sitting still in neutral - whether HST or geared. If you are going to be traveling, the transmission will take some of that power - a lot if the transmission is stressed.

Why is HST so popular? Because people drive automatics, and probably have a HST lawnmower. So they understand the concept of no shifting. They can also instantly change speed or direction with only one foot.

Here is what has not been said here. HST is noisy. I had an L3800 HST and found that if I had to push the transmission to 50% or more, there was a lot of noise. But to get the heavy beast to move I found myself pushing the pedal to 80-100% all the time. The screaming drove me crazy. I spent $200 just to replace the transmission oil with what I was told would abate the noise. That money was for the fluid - not labor. There was very little improvement. I sold that tractor with 100 hours.

At the same time I had a 2002 Kubota L3710 GST. I still have it and love it. Really do. The GST transmission is a dream. If I am to buy another Kubota, I would see if GST is available. If not then definitely geared. Dead last would be HST. That's my opinion, YMMV.

 

[ptsg]

Great post Rancher with nice points and common sense. I agree 100%.

 

[bcp]

Your land and work makes a difference. For hilly land, utility work, or loader work, I want HST. For flat land or mainly field work, I like gear.

Bruce

 

[LittleBill21]

I was going to make my own post, but this thread is close enough. I already knew i wanted a HST, but after using the tractor now for several hours, i think anyone in a small tractor not, mowing acre's for miles, would be absolutely nuts to buy a gear model. i move my tractor sometimes inches at a time, if i had to use a clutch the entire time, it would sit in the barn, HST on a small tractor is prolly 80% more efficient over gear. and no my HST doesn't whine, that seems to be a Kubota thing.

 

[piper184]

All drive trains consume power. Some more than others. For me I don't think fuel efficiency is much of an issue unless I was farming thousands of acres.
In my case it all comes down to reliability and repair-ability. Gear boxes are easy to fix. HST, not so much. I have more time than $$ so it is gearbox all the way. Learned to drive a stick shift and tractors with poor brakes on hills so shifting and footwork is not a big deal. Did run a shuttle shift a couple of times and find that a handy feature for loader work. More up front $$ so I make due without it. I can hear my neighbor's HST approaching way before I hear the engine. My riding lawnmower has a trans axle. Don't much like it but my wife does.
Now if I could just buy a new pickup with a real V8 and without that #@%$$^ automatic tranny.

 

[s219]

I had an L3800 HST and found that if I had to push the transmission to 50% or more, there was a lot of noise. But to get the heavy beast to move I found myself pushing the pedal to 80-100% all the time. The screaming drove me crazy.

That is about the opposite of what you want to do. It was like shifting into high gear. You should have modulated the treadle to a low setting (20-30%) and throttled up instead. No wonder it made so much noise for you! When an HST whines it's a good sign you're doing something wrong.

I also have an economy L model and this is one of the noisier HSTs Kubota sells, but there is a difference between normal noise and intense whining/screaming.

 

[3gunr]

My hst only whines when at low rpm and barely moving forward or backward , Otherwise it is not bad at all. I do wear ear protection when mowing or tilling for long periods.

 

[ArlyA]

Gear box trannys loose a pretty small percent of HP, like in the 1 or 2% area.

Constant Velocity Transmission (CVT) come in next with a tad more loss, like in the 3 or 4% but I'd say that still reasonably good.

HST loose quite a bit more HP but how much, depends on where the transmission is being operating at. That is if you're trying to go fast, then its loses are rather high. There losses vary from something over 5% to 15. This is why slower machines tend to use HST systems since they don't need to go high speeds anyway.

 

[Stan B]

My hst only whines when at low rpm and barely moving forward or backward , Otherwise it is not bad at all.

Yeah, ditto. Or when cold.

 

[Bearcat81]

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.

I agree. And, gears are maybe less prone to 'go wrong' (as my thrifty relatives would say) versus the 'more complicated' HST. I have both. Plowing and 'bush-hogging' seem easier for me in a gear. My wife prefers the HST...