In the Sears and Husqvarna tractors, any tractor listed as an automatic use hydrostats, some pedal operated, some lever operated.

In MTD-built tractors, particularly those in the MTD-built Yardman, Troybilt or Toro brand names, MTD regularly uses a variable pully system formerly known as vari-drive. The speed at the tractor rear wheels is controlled with a foot pedal that varies the size of one of the two pulleys in the belt drive setup.

Varidrive setups are widely seen as technically less sophisticated than a hydrostat filled with engine oil, but MTD has used this system for ages. Their 6- and 7-speed shift-on-the-fly transmissions used in low priced Yard Machine and Bolens models is essentially a lever-operated vari-drive with notches for each "gear".

FWIW a hydrostatic is not a "true" automotive automatic transmission either, tho both have "fluid." To further complicate matters many new cars now have CVTs(continuously variable transmissions) which are the automotive version of the pedal varidrive system MTD uses on theit Troybilt and Toro models.

Then why are some of the sears listed as automatic and hydro and the auto listed units do not mention anything about hydro on the spec page? Is it just a marketing point so all their tractors don't appear to be the same?

"An automatic transmission (commonly abbreviated as "AT") is an automobile gearbox that can change gear ratios automatically as the vehicle moves, thus freeing the driver from having to shift gears manually (similar but larger devices are also used for railroad locomotives)." Wikipedia

"A hydraulic or hydrostatic drive system or hydraulic power transmission is a drive- or transmission system that makes use of a hydraulic fluid under pressure to drive machinery." Wikipedia

So if one tractor had hydro operated witha a lever on the fender and another had auto on the fender would an operator of the tractor notice much difference? For both of them; you just push lever forward to go right?

You can have an auto that is gear driven or one that is fluid driven (hydro). If you are using the tractor for it's intended purpose, both should do fine.

To my knowledge all Craftsman are fluid driven. A belt runs from the engine to the pump on the transmission, the lever or pedal operates a valve to let fluid go in either direction. The more you open it the faster it goes. I think you are right in saying whatever they want to call it is for marketing. Some people will understand when a salesman calls it an automatic, but would be confused if he called it a hydro

"lever or pedal operates a valve to let fluid go in either direction. The more you open it the faster it goes. "

Actually I think you will find that the lever or pedal operates mechanism that changes the angle of a swash plate which then causes a series of pistons around it to take longer or shorter strokes.

Walt Conner

cwenisch,
the relevant thing is what kind of tasks do you plan for your tractor. Sears uses the terms hydro and auto interchangeably but they are talking about the same thing. Basically you push on the pedal and the harder you push, the faster it goes. Auto's, hydrostats are better for just mowing or for your snow blowing as long as you don't have steep grades and as long as you don't plan to do a lot of plowing or using ground engaging attachments like harrows for your garden. Manual is better for the heavy stuff but of course you have to select your gear. I don't have any problem with the manual but most people like the "auto" because it's easier to control the exact speed. One other thing I should mention is that with an auto they will often tell you that it never has to be serviced. This is not true. First and formost you have to keep the tranny clean so that it cools effectively and doesn't cook the oil. Second it's a good idea to change the oil once in a while.

The information above on the differences in the names is correct. I know that does not help in choosing the best lawn tractor but if I could offer another point to consider? The most important part of these systems which I had to learn the hard way is: How the transmission is connected to the handle or pedal used to control it. I have a 3 year old Craftsman T2500. This uses rod and linkage to operate the valve from the pedals to the rear of the tractor (transmission). The engineering on this is horrible. There is not enough angle to the connecting rods to move the valve smoothly. The pedals constantly jam as the rods try to push directly inline with each other.

I would double check how the pedals are engaging the transmission prior to purchase. If belts are used instead of direct linkage this would be preferable. My old Craftsman tractor used the lever for speed and direction. I loved it although it took a day or two to get used to it.

I hope this helps?

Me, too. I have never seen a control that used belts connecting the control handle or foot pedal to the control valves. My 28 Wheel Horse uses a rod to connect the foot pedal to the hydrostatic transaxle. It has never been any kind of problem.

I wonder if HU above is referring to a continuously variable system that uses variable pulleys and belts to transmit power? Or maybe his individual mower has a problem with the control linkage?

I'm curious. tom

I'm sure it is my model with the issue. I have not seen many others complaining of the same issue. On mine, it uses a rocker pedal (fwd-rev) on the same pedal. The issue is attempting to move the pedal in the opposite direction causes the push rods to align with the fulcrum of the valve connection which locks up the pedal until you are able to move it back and forth several times in order to jossel it off center.

.

Thanks for the clarification. I bet you have something bent or a lever that has rotated on the shaft to a point it can't function properly. Maybe a pin that has sheared. I can't see a manufacturer designing something like bad geometry into a control linkage. I bet something is broken, bent, twisted, or loose.

tom