Does Hydrostatic Drive work on hills?

Get the gearshift, she'll learn to like doing wheelies. There is no upshifting like a car, you put it in a gear and take your foot off the brake, that's it. Gear 1 is granny, 1 mph; Gear 6 will bring the front wheels off the ground usually. If you get up the driveway with the hydro, it's only going to freewheel back down. They are made for level or rolling yards, not slopes.

I think you would be better off with the garden tractor version. they have a larger hydrostatic transmission that works with a higher internal oil pressure to be able to pull heavier loads (which would consist of you, the tractors weight, the weight of the snow equipment and any wheel weights you might have)

Failure of the hydro is disconcerting. Evidently the fluid is so thick (from the cold?) that the hydro's pumps aren't producing sufficient preasure. Do you allow the transmission to warm up before use? Have you tried purging the transmission?

I have found that resistance from hills or ground engaging equipment causes the hyraulic oil to overheat & greatly diminishes the pulling power. Belt drives are more user friendly than they use to be.

Firsttractor said…

Failure of the hydro is disconcerting. Evidently the fluid is so thick (from the cold?) that the hydro's pumps aren't producing sufficient preasure. Do you allow the transmission to warm up before use? Have you tried purging the transmission?

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Actually the tractor did worse the longer it ran.  Trying to get up the drive I shut it off and let it sit on the hill for an hour a couple of time, then I could get maybe another 100 feet.  I ended up having my wife drive and I pushed.  I had purged the transmission several times, but it still would not go up the hill.

The spec at hydro-gear says the output torque for the LT series is 160 lb-ft which through a 20" tire would give a forward pull of under 200 lbs.

The garden tractor series is a bit better, with up to 260 lb-ft of torque continous but with 24 inch tires still only gives 260 lbs of pull. The GT series can have 510 lb-ft intermittent, which would give 510 lbs of pull - but not for long.

According to my calculations, even the GT series transmission will transmit less than 3 hp to the ground. (1800 rpm input / 30.6:1 reduction = 59 rpm * 260 lb-ft / 5252 = 2.91 hp).  Why have a 26 hp engine.

I went with a garden tractor but the 6 speed gear drive.  I want to spin the wheels or stall the engine.

Maybe you shouldve thought about this before you moved to a hill

Rebuild your house some where nicer

Thanks for the follow-up. I had less than a year of engineering and that was 40 years ago, so I'll defer to you on the calculations. Your choice of the manual transmission appears to be the best route to take. Buy a couple of back up drive belts.

Now I'm really concerned about being able to snow plow with my hydro- time will tell I guess.

One follow up question. Did you own the tractor early enough in the year to use it for mowing? If so, did the trany show any signs of this failure on hills etc.?

I went with a garden tractor but the 6 speed gear drive.  I want to spin the wheels or stall the engine.

There used to be a dual range 6-speed Peerless by Tecumseh that was a beast.

I don't know what to tell you. I was concerned after reading your post, but the only thing that stops my 24hp hydro in stacking large piles of snow is the wheels spinning and thats with my 200lbs+, wheel weights and chains and a TON of snow. I'd say size for size, it moves as much snow as the city plow which I've seen spin its wheels when it reaches its limit.

only  time my 26 hp hyrdo let me down was when i was trying to pull a truck with no wheels across my yard. the tractor has ag tires so after they dug a hole they got too much traction and the hydro didnt provide enough torque.  but who tries pulling a truck with no wheels across a yard???

According to my calculations, even the GT series transmission will transmit less than 3 hp to the ground. (1800 rpm input / 30.6:1 reduction = 59 rpm * 260 lb-ft / 5252 = 2.91 hp).  Why have a 26 hp engine?

If you do your math some more, you'll discover that 3 to 5 HP is more than sufficient to propel the tractor's own weight plus your's and a typical pulled load within the speed range of the machine up to the design grade limits.  The bulk of the shaft HP on any lawn or garden tractor is needed to operate the mowing deck particularly those designed to accept mulching blades.

When selecting a lawn or garden tractor, you need to pay particular attention to the size and style of mower deck and determine if it is appropriate for the frame size of the machine.  Don't make the mistake of under-powering the machine or putting too large a deck on a machine to save a few bucks.  You will end up paying for it in other ways like aggravation, poor mowing jobs, taking much longer to get a decent job done and more frequent repairs.  

Another thing to keep in mind is to pick out a machine that uses three smaller blades rather than two larger ones.  Again, they cost a bit more but do a much better job and require less maintenance.  Two-blade decks require that the blades be synchronized by using cogged belts or slightly offset from one another to create blade overlap. (You don't want to be sitting on a machine when a cogged belt slips and the two blades hit one another!)  Three-blade decks typically have the center blade positioned slightly forward of the outside blades which enables sufficient cut-overlap without using cogged belts.

Depending on the frame, manufacturer, weight of machine and traction, a hydrostatic transmission should be able to straight climb a 30%to 40% grade (with GT's hitting the higher value).  If it doesn't, then it is either a poor quality machine or there is in fact a problem with the drivetrain.  I use a Husquavarna 26 HP GT with AG tires and sleeve hitch that is otherwise stock.  I use it with a grading box that will in fact hang the machine up a lot when working an area with a lot of roots but when it does, the wheels will spin and dig a hole.  I also have a lot of drainage swales around my property that are quite deep/steep that the machine climbs in and out of quite easily with the slope being at least 50%.

Most Husquavarna and Sears tractors are made by Electrolux in Georgia.

If I remember correctly, the PYT9000 uses a Tuff-Torq K46 transmission.  It may be a K55.  In any case, the K46 is a light duty transmission that is rated at 117 lb. ft. of continuous duty with a peak intermittent capability of around 400 lb. ft.  This does not have any relation, in the way you describe, to the weight it will push.  If that were the case, it would be unable to move its own 600 lb. self.  What that rating does mean is this.  if you were able to put a wrench or bar one foot long on the axle, it would have a maximum force of 400 lbs. one foot from the axle.  that is more than enough to cause the wheels to spin even on bare tar.  Keeping in mind that placing a continuous torque load of more than 115 lb. ft. will cause overheating and possible damage if done so regularly.  So to climb the hill at your house should be childs play.  You may have a defective transmission.  Does it make a unusually loud "whining" noise while trying to climb the hill?  To troubleshoot, I would first replace the belt running from the engine to the transmission.  It may be stretched or glazed causing slippage when a high load demand is placed on the transmission.  A tip; For best performance from a hydrostatic transmission, always run the engine at full throttle to ensure maximum pressure within the hydraulic motor.  I would next ensure that the transmission is full of fluid.  There is a bolt plug on the right side of the transmission about one third of the way from the bottom going towards top.  Remove that plug and the oil should be at that level, you should be able to stick your pinky finger in the hole and the oil needs to be up to or very close to the hole.  If it is low, go to a parts store and get a quart of 10w-30 and a transmission filling tube that screws onto the top of the oil bottle so you can squeeze the oil in until it begins to run out of the hole.  if these steps fail, your transmission will need to be serviced by a professional.

Hi kbowley,

To begin, a tractor with snow blower, 75 pounds of sand in the rear weight, two 30 pound wheel weights and a 200 pound operator is more like 1100 pounds.  Tractor 600, snow blower 200, operator 200, weights 135.

On a 10 degree grade, the 1100 pounds will resolve into sin 10 X 1100 = 191 pounds parallel to the grade and cos 10 X 1100 = 1083 perpendicular to the grade.

You need more than 191 pounds of force to move the tractor up the hill with zero rolling friction.  In other words if you tried to pull the rig up the hill with a rope, you would have to pull the rope with more than 191 pounds of force to move the rig.

If you have 117 lb ft of torque on the 20" rear wheels you have 117 * 12 / 10 = 140.4 pounds of continuous force from the rear wheels.

Trying to drive the tractor up a long 10 degree grade would appear to overload it - and indeed it did.

I have exchanged the tractor for a gear drive garden tractor but have been fortunate that the rig is more of a snow repeller that a snow mover. It hasn't snowed since the replacement arrived.

I have a YTS4000.  I havent had the chance to tear up the yard yet but plan to... I read at mytractorforum.com of a similar problem that was solved by "purging" the transmission.  The process is in my owners manual something like go ahead 5 ft let it sit a second or two then back up 5 feet or so and so on and so forth a few times.(I'm paraphrasing so just know thats not the actual direction but close)  This may help with yours or maybe not.

i suggest buying one with a shaft drive. i have a cub cadet with a 42" snowthrower. my driveway is uphill at 20 degree grade and it works great. even in 12" of snow.