Difference between automatic and hydrostatic

cwenischSeptember 6, 2007

Can you explain to me what the difference between automatic and hydrostatic are? As I look at the Sears webpage some tractors are hydrostatic and some are just automatic.

Thank you for reporting this comment. Undo
davidld(central KY)

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.

    Bookmark   September 6, 2007 at 1:22PM
Thank you for reporting this comment. Undo

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?

    Bookmark   September 6, 2007 at 1:30PM
Thank you for reporting this comment. Undo

"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

    Bookmark   September 6, 2007 at 2:29PM
Thank you for reporting this comment. Undo

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?

    Bookmark   September 6, 2007 at 3:36PM
Thank you for reporting this comment. Undo

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.

    Bookmark   September 6, 2007 at 5:31PM
Thank you for reporting this comment. Undo

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

    Bookmark   September 6, 2007 at 9:10PM
Thank you for reporting this comment. Undo

"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

    Bookmark   September 6, 2007 at 9:58PM
Thank you for reporting this comment. Undo

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.

    Bookmark   September 7, 2007 at 12:42AM
Sign Up to comment
More Discussions
Kohler Engine Question
I bought a Kohler Lawn tractor engine. New. sv740-3024.Two...
Craftsman LT 1000
Craftsman rider LT 1000 917.271851 032502D005822 Engine:...
Craftsman 917.289244 - Starter will not turn the flywheel
I am working on a Craftsman 917.289244 with starting...
Hydrostatic Drive Problems??
Craftsman 20.5 HP Kohler Command V twin Under the seat...
Briggs & Stratton OHV Intek Hard Starting
I am another of the seemingly many people fighting...
Sponsored Products
Ananas Wall Sconce by FontanaArte
$373.00 | Lumens
Arcadia Chinkapin Random Brick Glass and Slate Tile
$19.99 | TileBar
Nautical Flag Throw Pillow Set
$49.99 | zulily
Spanish Olive Large Wooden Serving Tray
Classic Hostess
Canto Satin Nickel Three-Light Bath Fixture with Vanilla Matte Glass
$391.50 | Bellacor
Bocci | 28.37 Thirty-Seven Pendant Chandelier
DENY Designs Gabi Sea Leaves Outdoor Throw Pillow - 15845-OTHRP18
$49.00 | Hayneedle
Riverbank Saddle Bar Stool
Grandin Road
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™