There has been quite a bit of discussion about manual vs hydro transmissions for plowing, snow blowing, hill climbing and pulling a load.
Let's start with the obvious.
First,a lawn tractor, is for mowing. It is not primarily designed to haul, plow or blow snow. It does it's primary purpose well and it may or may not do secondary tasks as well. (A snow blower blows snow very well but it does a poor job of cutting grass.)
Secondly, a tractor with a hydro transmission will make mowing a lawn with a lot of landscaping a breeze and will mow large open fields just as easy as any other tractor transmission. A tractor with a manual transmission will make mowing large open fields a breeze but make mowing a lawn with a lot of landscaping a tedious pain.
Thirdly, a hydro trnsmission is less efficient than a manual transmission. (there is a loss of engine torque because of the automatic transmission. Not a massive amount, but certainly a measurable amount.)
I bought a tractor with the hydro trnasmission primarily because of its convenience in mowing. I had concerns in its reliability and after researching it, I was satisfied that it was as reliable, if not more reliable, than a standard transmission. I also plan to plow snow with it. After reading that people were having problems with it going up hills and for snow removal, I decided to do more research (should have done this before my purchase, but I didn't)
So I have done a lot, and I mean a LOT of research.
The first thing I realized is that I need to re-learn my understanding of making the tractor go. It's contrary to my natural instincts. With a car, when I push the pedal down, the engine turns faster and puts out more hp and torgue to the transmission which makes the car go faster. With a tractor the engine is to be run at its fastest optimum speed already.
The blades and deck are designed to work best at this maximum engine speed. Lower the speed of the engine and the cut is poor. (Consider how well an axe would do if you tried to push it through a tree rather than swinging it to make a cut.)
Consequently the trnsmission is designed to operate at maximum engine speed. So speed of the tractor is controlled by the transmission. With a manual tranny, if you start out in first gear with maximum torgue going to the wheels and if the load is too great, and the wheels don't have enough traction, the wheels spin. If the wheels have traction and the load is too great, the engine stalls. Either way, the load is too much for the machine and the task cannot be done. Shifting from first gear to fourth gear wont help. Such is the reality of physics.
From the numerous sources I have read, the hydro will put out almost as much torque to the wheels as a manual tranny will.
A hydro trnasmission consitsts of two units, a pump and a motor. Because the engine is running at maximum speed and the hydro pump is direct belt drive off of the engine, the pump is always operating at maximum. In nuetral, no fluid enters the motor, it flows through a bypass valve and returns to a reservoir to be rcycled though the pump. When the pedal or lever is moved, a valve is opened to allow fluid from the pump to enter the tranny motor. The further you push the pedal down or move the lever forward the more fluid is alowed to pass into the tranny motor. The more fluid into the tranny motor, the faster you go. For instance, one gallon of fluid per second to the motor makes the tractor move slowly and four gallons per second makes the tractor move faster. But, whether it's one gallon or four, the preasure created by the pump is the same, so the torque/power to the wheels is the same because the pump is always producing at its maximum. If the hydro wont handle the load at a small depression of the pedal or movement of the lever, it's not going to handle the load at a greater depression of the pedal or movement of the lever any more than a manual tranny will handle a load better in fourth gear than it handles it in first gear. Apparently,the difference is, instead of stalling the engine as happens with a manual, the hydro will send fluid to a bypass. The problem is when you are trying to send more fluid though the motor and there is too much load, the fluid will heat up, making the tranny heat up, which causes wear and eventual failure.
If the tractor with a hydro wont handle the load at slow speed, increasing the speed will only cause the tranny to fail. Likewise, if a manual wont handle the load in first gear, it wont do it in fourth gear. The difference is with the manual you'll ruin a belt and with the hydro you'll ruin the tranny---either way the job wont get done. So, use some common sense and save yourself some expense and frustration by knowing your machines' limitations.
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