Hydrostatic Transmission

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Hey, guys. My Craftsman mower has a Hydrostatic (it actually says Automatic Transmission on the fenders, but I'm sure that's a marketing thing) Drive tranny in it. I've ran it for 12 years, probably have over 1500 hours on the thing, and change the motor oil every 3 months, using Pennzoil HD30, but have never changed the trans gear oil. Should I? It still works just like when I bought it.

Dave
 
I Would Dave....maybe use a synthetic 10W-30 or Amsoil's 5W-30 Hydrostatic oil. I did and it works quieter and cooler. Get the pump from Amsoil and fill from the bottom up.

I sent a sample to Blackstone with 200 hrs on it with a Tuff Torque Q61 Trans. WIll let you know the resutls soom.
 
The problem is, 99% of your lower cost lawn tractor hydro drives will not have a drain plug. A drain plug is VERY rare, although, I have seem some heavier duty MTD and Sears units with spin-on filters, drain and fill plugs. Your typical Sears unit will have a top expansion tank or a breather vent you'll need to drain/fill from. FWIW, bottom filling (like a marine outdrive) is not going to keep air out of a hydrostatic drive. The swash plate piston pump will always pick up a blip of air upon restart and has to be running to purge it. No worries on that at all.

Joel
 
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If I knew all the info in this thread when I bought my tractor I would have made sure it's transmission had a spin on filter and was easy to fill and drain.

My Tuff Torque is easy to drain and fill but has in internal filter that requires cracking the case in half to change it.

So I only drain the oil every 200 hrs. The book says every 400 hrs or upon teardown and use Amsoil 5W-30 Hydrostatic Oil.
 
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Pete, with your drain/fill regimen, I wouldn't worry about the internal filter. The pump will probably wear out before that filter would come close to clogging. On the MTD and Sears/AYP units I've seen with a Hydro-Gear and spin-on filter, those babies were a good 10yrs old, or older. My FIL has a 10yr/old MTD Yard Man tractor with a 20hp horizontally opposed Kohler Magnum. It has a fender shift Hydro-Gear hydro drive with a spin on filter. It runs fine, but everything is sloppy on it. The deck hardware is such that he keeps chewing up the deck drive belt.

Joel
 
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I can't find a pic on it, but basically a hydrostatic drive is an axial piston pump and drive motor all in one. Check this link for swashplate here: http://en.wikipedia.org/wiki/Swash_plate I'm a green horn at this but, mashing the go pedal or motion lever on your hydrostatic drive machine tilts the swashplate pump such that the pistons pump the maximum amount of fluid to the drive motor = max speed. Pulling backwards tilts the plate the other way making the motor go backwards = reverse. Keep the lever or pedal in neutral mode causes no pumping. Some commercial machines use separate hydraulic pumps connected to hydraulic motors via hoses. Speed and direction are adjusted by levers and valving. Commercial zero turns are like this, as are Ingersoll garden tractor's Hy-drive system.

Joel
 
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Tuff Torque K61

500 hrs total.

Ran original 10W-30 oil for 300hrs..did not send in sample but changed to M-1 10W-30.

200 hrs later sent a sample to Blackstone. Wear was low compared to averages. No moisture or insoluables.

Easilly could have went 300-400 hrs as recommended by the manufacturer.

Oil did shear down a bit but not enough to hurt anything.

No evidence of any mechanical problems developing.

I think I will perhaps change @ 200 hrs from last drain and send in another sample.
 
Its not working right again on the M1 15W50. Which is alright, since just before this cropped up, we had a failure in the deck drive engagement and we couldnt get parts to fix it (or even find anyone willing to make the part). So the deck has been scrapped and the mower duties replaced with a new tractor. Still, I was hoping to use the tractor for other things..
Its not going completely neutral like on the RTS, but its making ALOT of noise and going slower than normal.. I dont think Ive yet found the correct viscosity.
 
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Onmo- It sounds like that pump is just plain worn out. Noise means it's either air bound or bypassing like mad. As far as I know there is no/few user serviceable parts on the sealed units, but an on the ball OPE shop, machine shop, hydraulics place, etc.. can pull them apart, skim warped pump head plates, sometimes replace fluid manifolds, PRVs, etc..

Pete, I dunno how to describe a hyrdostatic drive other than it's a variable displacement piston pump manifolded to a fixed displacement piston motor. The swash plate on the pump tilts (connected to your motion/forward/rev linkage)to change the amount and direction of the oil pumped to the motor. The motor usually spins a reduction gear which feeds the differential.

Joel
 
"Air bound"? Could it just be low on fluid? I should check that.... Thats unfortunate that the unit may be bad.
:/ Could it have been damaged when it when it went neutral on the RTS?
 
Heh. Guess I should have checked that first. It was about an inch below the top. I dont know how it got low, as I filled it to the top. It is seeping a little though at the gasket between the case halves.
 
Found out that Tuff Torque in JD's recommends HYGARD and Amsoils 5W-30 Hydrostatic Oil is listed as a HYGARD synthetic replacement.

Now even though a 10w-30 is recommmended in the manual the JDHYGARD appears to around a 20wt product.

Conclusion..Amsoil ATH may be the best choice for Tuff Torque Transmissions.

http://www.amsoil.com/storefront/ath.aspx

The right balance of detergency and anti-foaming agents.
 
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New here so please be paitient with an old guy. I have a four year old Cub Cadet LT1050. I see why it is painted yellow as it has been a lemon from the first season for us. Between bearings, bushings, tie rod ends, stator, and the hydrostatic tranny, I could have bought a much better unit. The hydro-tranny has been acting up since the second season where I lost reverse and forward was slowwwwww! Not to mention if a tire went in a small rut I had to get off and push it out. I removed it to change the oil and ended up installing a drain plug as there wasn't any nor an oil filter. Drained the oil and noticed the expansion bottle was dry with no trace of oil ever being in it. Well filled it up again and used a drill to spin the fan/pulley to purge the air. It seemed to work alright after though it felt weak still, but now reverse worked. Season three was the same thing but this time I did some mods to the tractor which allows me to drop the tranny in about 15 minutes or less. Once more it seemed ok until last week. Once more the tranny comes out and checked the oil level. It was a bit low and still no trace of oil in the bottle. This time I filled it up AND put oil in the bottle to about 1/4 full. Finally the question, should I go to a thicker oil such as gear oil while it's out? It's pretty hot and hummid in South Louisiana and if so, will it screw up what's left of the tranny? Being on a fixed income prevents me from getting another mower and I need to try using this one for at least 3 to 4 more years before I can swing getting another one. Oh yea, I cut about two acres each week.

Rick
 
Originally Posted By: Rickus
New here so please be paitient with an old guy. I have a four year old Cub Cadet LT1050. I see why it is painted yellow as it has been a lemon from the first season for us. Between bearings, bushings, tie rod ends, stator, and the hydrostatic tranny, I could have bought a much better unit. The hydro-tranny has been acting up since the second season where I lost reverse and forward was slowwwwww! Not to mention if a tire went in a small rut I had to get off and push it out. I removed it to change the oil and ended up installing a drain plug as there wasn't any nor an oil filter. Drained the oil and noticed the expansion bottle was dry with no trace of oil ever being in it. Well filled it up again and used a drill to spin the fan/pulley to purge the air. It seemed to work alright after though it felt weak still, but now reverse worked. Season three was the same thing but this time I did some mods to the tractor which allows me to drop the tranny in about 15 minutes or less. Once more it seemed ok until last week. Once more the tranny comes out and checked the oil level. It was a bit low and still no trace of oil in the bottle. This time I filled it up AND put oil in the bottle to about 1/4 full. Finally the question, should I go to a thicker oil such as gear oil while it's out? It's pretty hot and hummid in South Louisiana and if so, will it screw up what's left of the tranny? Being on a fixed income prevents me from getting another mower and I need to try using this one for at least 3 to 4 more years before I can swing getting another one. Oh yea, I cut about two acres each week.

Rick


Try some Mobil 1 15W-50 in the trans..you will be pleasantly surprised.
 
Yep, I second the 15 or 20w50 recommendation for the Hydrogear trans in that Cub 1050. How does the oil look when you change it? Cub 1K series also had an issue with a weak spring tensioner for the engine to transaxle belt. Your drive belt could be slipping under load. In regards to the slow reverse speed; if forward speed is fine, this is most likely a linkage adjustment issue. If there was a an issue with the hydrostatic drive itself, you'd loose ground speed for both F and R.

Joel
 
I just change the oil in my Cub 1050, I used Amsoil 20w50 Motorcycle oil. I figured it would hold up better to oil shear, being motorcycle oil. The tractor had 90 hours and the oil was slightly dis-colored. But I wanted to get a beter quality oil in in it.

Rickus, I am curious as to what you modified to be able to get the axle out easiler. They aren't bad to take out but re-insatlling them is a pain, on these tractors. they have alot of springs to re-attach. And getting the control rods in position, while installing it back in, sucks.
 
I'm thinkin Rickus used velcro! I don't know of anyway to make that job easier aside from install a drain and a fill tube for easy access to the expansion tank.

Joel
 
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