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Hydrostatic Transmission - Towing Damage?


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#1 FilledTires OFFLINE  

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Posted February 01, 2015 - 09:42 AM

Hi There,

 

The Transmission in question is: Eaton 11 Hydro Transmission mated to Peerless 2500 Transaxle in Ford LGT 145.

 

The Question:

 

I recently got stuck in snow and ice when moving snowbanks with my Front End Loader. I went to tow it out with my car and accidently left it in High Gear. When I towed it, I heard two clicks of the gears, then ran back to move the lever into neutral to tow out of the ice pit I was stuck in.

 

Could this have caused damage to the Transmission or Transaxle?

 

Was the click I heard the gears in the transaxles moving the output shaft on the hydraulic pump?

 

This leads to another question about Hydrostatic Theory.

 

When the swash plate on the Transmission is in neutral (tractor not moving) is the oil pressure exerting onto the transmission output shaft, so it doesn't move? Or can the output shaft move feely at this point?

 

I was using the tractor again later on and I noticed when I let my foot off the pedals, when on a slight slope, the tractor rolled backwards. Is this suppose to happen or is the transmission suppose to hold pressure on the gears, preventing the wheels from rolling?

 

Thanks!

 



#2 Copperhead300 OFFLINE  

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Posted February 01, 2015 - 09:51 AM

More than likely when you pulled it out the tires slid on the ice as they have a lot of resistance to roll when the relief is not pulled and the front end loader acted as a counter balance removing additional weight from the drive tires.   Plus if you did not tow it a long distance, it will also not be damaged.

#3 tater195 ONLINE  

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Posted February 01, 2015 - 10:35 AM

Gts will exhibit some strange symptoms when moving snow. Let it thaw out good before you get too scared about breaking it. If you didnt tow it a half a mile at 30 mph, you should be fine

#4 FilledTires OFFLINE  

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Posted February 01, 2015 - 11:42 AM

I am sure his paranoid type post happens often! Thanks for putting my mind at ease.

 

I am still curious about the wheels rolling when in gear.

 

I just pulled my tractor up onto my trailer to test. When I stop half way up the ramp, the tractor begins to roll back slowly all the way down the ramp.

 

Isn't the fluid trapped between the Charge Pump and Motor suppose to "hydraulically lock" the wheels?



#5 tater195 ONLINE  

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Posted February 01, 2015 - 12:08 PM

Linkages could be packed with ice and creeping in reverse. What does it do if you back up the ramps?

#6 glgrumpy OFFLINE  

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Posted February 01, 2015 - 12:47 PM

Years ago when buying my first tractor, went to Deere dealer, a freind.  Told him also looking at IH and Case.  He says hydros, speed-up going downhill and need more lever push when going up, and reccommended the gear tractor. I bought the gear. I know Case's have Hill Holder feature, not standard, and I have had IH that did just those things when using it on my hills. I now have a PK hydro and it is not always in stop mode in N and seems to creep one way or other, unless I play with drive lever. I know most brands have a release button, rod, or ?? to make it towable. Have only had to use one on Wheelhorses, never other brands. I've never pulled long or fast on any of mine, and no problems so far. I've never heard, where is the release on these models? MTD 990 gas a lever to just put between the ranges and it works, same on yours?



#7 KennyP ONLINE  

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Posted February 01, 2015 - 01:30 PM

Years ago when buying my first tractor, went to Deere dealer, a freind.  Told him also looking at IH and Case.  He says hydros, speed-up going downhill and need more lever push when going up, and reccommended the gear tractor. I bought the gear. I know Case's have Hill Holder feature, not standard, and I have had IH that did just those things when using it on my hills. I now have a PK hydro and it is not always in stop mode in N and seems to creep one way or other, unless I play with drive lever. I know most brands have a release button, rod, or ?? to make it towable. Have only had to use one on Wheelhorses, never other brands. I've never pulled long or fast on any of mine, and no problems so far. I've never heard, where is the release on these models? MTD 990 gas a lever to just put between the ranges and it works, same on yours?

On these, there is N between Hi/Lo.


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#8 Sawdust ONLINE  

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Posted February 01, 2015 - 02:32 PM

The best way I have adjusted the lever is with the rear wheels off the ground. If your lever is adjusted right your rear wheels should not move, they may want to creep slightly but if adjusted properly you should be able to hold BOTH wheels from turning. My guess in neutral yours will creep in reverse to the point you can't hold them...normally a minor adjustment will solve this.
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#9 superaben OFFLINE  

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Posted February 01, 2015 - 05:07 PM

I agree with those saying that the linkage is not 100% right.  Its fairly common.  Jim is right, too, the only way to adjust right and know that it is right is to get the wheels of the ground.

 

Hydros still can freewheel.  No hydraulic motor is fluid tight, and it can still free wheel with enough pressure on it, although it is having to act as a pump and push the fluid back through the holding pressure of the pump.  If the engine is at idle it can freewheel a lot easier than if it is running at high RPM.

 

Ben W.


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#10 FilledTires OFFLINE  

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Posted February 01, 2015 - 06:10 PM

Thanks. The linkage is adjusted, wheels aren't creeping. When wheels are off the ground they don't move when hydro level is in neutral.

I just wanted to verify a certain amount of free wheel was normal when in gear and pump running.

Thanks Ben for verifying that. It was my understanding that when the swash plate in the transmission is vertical, there is fluid between the swash plate and the motor. That fluid I thought would essentially lock the output shaft in place. It appears maybe in a perfect scenario that would happen but in the case of these 40 year old transmissions maybe more internal leakage happens in this area?


Edited by FilledTires, February 01, 2015 - 06:15 PM.

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#11 tater195 ONLINE  

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Posted February 01, 2015 - 06:57 PM

Sometimes the bypass valve will stick. Does it seem to push good under a heavy load?

#12 FilledTires OFFLINE  

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Posted February 01, 2015 - 09:24 PM

Sometimes the bypass valve will stick. Does it seem to push good under a heavy load?

Oh yea she has lots of push in her. Perhaps the cold is making the bypass a little stiff? It has been in the teens to below zero temps for the past several weeks.


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#13 superaben OFFLINE  

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Posted February 01, 2015 - 10:26 PM

Oh yea she has lots of push in her. Perhaps the cold is making the bypass a little stiff? It has been in the teens to below zero temps for the past several weeks.

 

Cold is another factor.  Expect the tractor to handle in a strange way until the fluid warms up to full temperature. 

 

Ben W.


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#14 TUDOR OFFLINE  

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Posted February 04, 2015 - 03:35 AM

Thanks. The linkage is adjusted, wheels aren't creeping. When wheels are off the ground they don't move when hydro level is in neutral.

I just wanted to verify a certain amount of free wheel was normal when in gear and pump running.

Thanks Ben for verifying that. It was my understanding that when the swash plate in the transmission is vertical, there is fluid between the swash plate and the motor. That fluid I thought would essentially lock the output shaft in place. It appears maybe in a perfect scenario that would happen but in the case of these 40 year old transmissions maybe more internal leakage happens in this area?

As superaben has stated, there is a certain amount of internal leakage in any hydraulic pump or motor, otherwise it would be seized solid. Parked on a slope the pressure will be such that the fluid will be forced out through the normal clearances and by the time the rear wheels have turned less than 1/4 turn, the tractor will freewheel.

 

The difference between a 40 year old hydro and one that is brand new is only in how fast that leakage occurs not in whether or not it will occur.

 

I doubt that there is damage to either the Eaton or the Peerless towing it a short distance at low speed on snow. As has been stated, the tires will slide before serious damage can happen. The hydro can spin the wheels with little effort, and the same goes for power going the opposite direction, there is little pressure built to cause damage to the hydro.

 

There is a slim possibility that the clicks you heard were the cast iron pinion yolks in the final drive cracking. I've run mine for years with those yolks cracked, but I do change them out, if such is the case, on those rare occasions when I have the final drive disassembled.


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