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Discussion Starter #1
Hi,

I am a recent owner of a new Craftsman 22 hp hydro static Lawn tractor. Nice machine, no complaints! I really like the infinite speed settings with the tranny and as such, i am varying the speed from medium to very slow around the fences, shrubs and even sharp 90 degree bends. I do this so i dont run into anything and also i am able to get a closer cut. I don't tow anything, or attach any implements whatsoever, its just for cutting grass ( 1.9 acres)

By doing this constant 'feathering' of the speed, am i shortening the life span of this tranny? Sorry i am unsure of the model of tranny, but probably its the lightest one they put in it.

thanks,

Grass_man
 

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I asked a similar question several months ago, although my concern was constant switching between forward and reverse, like during snow removal. The answers I got seemed to indicate that the hydro doesn't care how fast or which direction, as long as it's not overworked and overheated. Probably a Tufftorq K46 in your LT, fine for mowing, and even light towing, unless you have steep hills and/or extreme heat. You should be just fine. The only other tip I can offer is keep the cooling fins on top of the hydro clear of grass and other debris. Welcome to the forum!
 

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I agree with ggsteve. You won't hurt it by going slow. I second about keeping the cooling fins on the hydro clean, since heat is a real enemy. Does yours have a fan on the tranny? If so, the engine speed has a lot to do with cooling of the tranny. When mowing, the engine should be run at max RPM's so the engine and the tranny get sufficient cooling. (There are some who disagree, though.) I run my hydro (Tufftorq K66) pretty hard, and after 150 hours, not a hint of trouble. If I'm towing a light load a short distance, I will run the engine about half speed, but when mowing or towing uphill, it's full RPM's, with a short idle period before shutting the engine down.
 

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Agreed, keep the RPMs up. Varying the speed on the hydro is fine and so too is changing direction as long as you do it gradually and not in jerky motions.

90% of my driving is with one hand on the steering wheel and the other on the travel lever. I plugged the neutral detent to ease shifting from reverse to forward.
 

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run teh engine full throttle and set your speed by moving teh hydro pedal as much as required. the hydro is still pumping the exact same volume of fluid whether sitting still or going wide open. the difference is is how much is going thru the bypass portion and how much is going thru the rest of it.
 

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I have used my MTD's hydrostat often the same way,"full speed ahead" for the open areas,and I yank back on the lever to slow it down as I approach obstacles..I run the engine at full speed,which on my Kohler is only about 2500 rpms by the sound of it..I feel it keeps the tranny cooler by spinning the fan on it faster,and also keeps the pump pressure in it higher,allowing for better pulling power..I have heard low pressure can damage a hydro just as mich as excessively high pressure can,not sure how true that is..

About the olny things that seem to kill hydros are a lot of heavy overloads or hill climbing,and going from full speed forward to reverse at full throttle could snap an axle shaft or do internal damage..most of the ones I have seen that are "dead" simply slip under a hill climb situation or wont propel the tractor at all in either direction..
I think if they had a "low range" on a hydro it would live a lot longer and allow it to pull heavier loads without damage myself,but few folks would be willing to drive something that "slow" that only goes 2-3 mph..I know one guy who swapped 8" rims and tires onto his hydro tractor in place of 12" tires,and it lowered the gearing enough to cut top speed in half roughly,(and ground clearance!)--but man,with loaded tires with wheel weights and chains,that thing could PUSH some snow!..
 

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the hydro is still pumping the exact same volume of fluid whether sitting still or going wide open...
I cannot speak to all brands and models but at least on my Hydro-Gear, that is not the case. Borrowing from their service manual:
Output of the oil flow is
controlled by the direction and amount that the
variable swashplate is angled. As the pump
pistons compress they force the oil to flow
through one of two passageways (forward or
reverse) in the center section to the motor
cylinder block and motor shaft. Since the motor
has a fixed displacement angle it is forced to
turn with the flow of oil. As the angle of the
pump swashplate is increased the amount of oil
being pumped will increase and cause a higher
speed output of the motor. Reversing the angle
of the swashplate will reverse the direction of
oil flow.
 

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Discussion Starter #9
Hi,

I was able to find the model number of the tractor under the seat it reads:
944.609220. the model on the side of the hood says yts4000 (canadian nomenclature) 22 hp twin, 42 inch deck.

Is there a site that can tell me the make and model of the tranny from the craftsman model number above?

I am curious about the reputation of this tranny, it works great on level ground, but in one portion of my lawn where it slopes up to the house (10 degree) ,i can really notice it slowing down. I only have to go up this incline maybe five times during a grass cutting, but its annoying.
 

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Hi,

I was able to find the model number of the tractor under the seat it reads:
944.609220. the model on the side of the hood says yts4000 (canadian nomenclature) 22 hp twin, 42 inch deck.

Is there a site that can tell me the make and model of the tranny from the craftsman model number above?

I am curious about the reputation of this tranny, it works great on level ground, but in one portion of my lawn where it slopes up to the house (10 degree) ,i can really notice it slowing down. I only have to go up this incline maybe five times during a grass cutting, but its annoying.
Good luck with that model number, I went through the same problem with my DYT4000 model 944.605921, they just don't show up on American sites. I finally called Sears Canada and ordered an owner's manual for $12, which is a rip off when you can get all the American models online for free. But it is a good manual with all the parts lists etc.
 

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LL,

Where the heck is the swash plate? I need to look at my exploded diagram again because I must be missing where it is. I know what a swash plate is! :)

I am still confused by how my hydro-gear works. I've studied the exploded diagram and I am just not getting it.. I guess I really need to take it apart to understand, and I'm not going to do that :)
 

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I cannot speak to all brands and models but at least on my Hydro-Gear, that is not the case. Borrowing from their service manual:
Yup. What you put in your post is right on. This is how ALL hydrostatic drives function. They are basically a variable displacement pump manifolded to a fixed displacement hydraulic motor. A swash plate pump is just a circle of little pistons in a radial layout that rotate like a Gatling gun and are actuated as they rub against a plate that tilts from it's center (like an automotive a/c compressor). The more it tilts, the more stroke half the pistons have and the more oil is pumped. Tilt full the other way and oil flows in the other direction for reverse. The HyDrive system on my little Case tractor is the exact opposite. This is a fixed displacment pump piped to a fixed displacement motor. Speed and direction are all done by valving. Hydraulically, a hydrostatic drive is more efficient since no swash plate tilt means no oil is being pumped = no (or little) wasted energy.

Joel
 

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Now I get it!
 
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