Go Bottomb2910 hyd noise in high gear
 | ampebob
Join Date: Oct 2004 Posts: 16 piedmont ohio 
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2004-11-11 100199
Thanks for all the previous ideas posted on plowing snow! I ordered chains for the rear.
When in High gear,on a flat paved road or going down hill at about 3/4 throttle, I frequently get kind of a scream or ringing from what sounds like the front axle housing. Any ideas on what might be the cause? Do any of you know if the noise is a problem.
Bob Brown
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Add Photob2910 hyd noise in high gear
 | AV8R
Join Date: Oct 2003 Posts: 882 North Central Wisconsin 
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2004-11-11 100204
Is the 4wd engaged? There will be some gear noise from the slight mismatch of rotation when moving quickly.
If not, check for play in the front drive shaft support bearings (in axle and trans). It may have some play there. ....
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Add Photob2910 hyd noise in high gear
 | beagle
Join Date: Jan 2004 Posts: 1333 Michigan 
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2004-11-11 100208
My 7800 has the sam drivetrain and I don't recognize the noise you are descibing, so I would be a little concerned. How many hours do you have on the machine? Have you checked the front axle fluid level? The noise you descibe sure does sound like bearing noise, but are you sure it isn't the hydro whine. I certainly have more hydro whine in high gear than in either of the other two ranges, which is normal. ....
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Add Photob2910 hyd noise in high gear
| ampebob
Join Date: Oct 2004 Posts: 16 piedmont ohio
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2004-11-11 100215
Well I never run 4 wheel in high gear. The front housing is filled with UDT/ my dealer. Let me explain some more. When on flat paved road the noise begins after the machine (in high gear)reaches speed (rpm~2200). If I reduce speed, slow down say to 1000rpm the noise stops. If I stop and put the machine in mid range and run the same (2200rpm) no noise. If I go down a steep slope in high `1500 rpm the noise is back.
Could it be hydraulic cavitation? This could be hazardous to the pump system. ....
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Add Photob2910 hyd noise in high gear
| ampebob
Join Date: Oct 2004 Posts: 16 piedmont ohio
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2004-11-11 100216
Sorry forgot--320 vey easy hours. This has occurred from the day I purchased the unit.
What is the nature of hydraulic whine? ....
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Add Photob2910 hyd noise in high gear
 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York 
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2004-11-11 100218
I doubt that it is a hydraulic noise but gear noise. Can you isolate it from side to side or center? Do you have the ability to raise the tractor on jack stands on all four and run it in four wheel drive to get the noise? You have bevel gears on both sides of the tractor and a set of gears in the center. One set or the others are not quite machined right to cause this noise. You can run it in four wheel drive for this test as there would be no ground contact with the ground and tires to cause wrapping. If you could do that then the dealer will know exsactly where to go to solve the problem and you will know where they need to fix because of your work in isolating the problem. ....
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Add Photob2910 hyd noise in high gear
| beagle
Join Date: Jan 2004 Posts: 1333 Michigan
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2004-11-11 100219
Make sure you check the hydraulic fluid level and the hydrostat filter. You want to be sure the hydrostat charge pump isn't starving for fluid.
The whine is from the hydrostatic transmission which is a seperate closed circuit system form the rest of the tractor hydraulics. When you operate in a situation where the drive motor works against the drive pump, down hills for example, or in high range, where back pressure increases against the pump, the pump will start "complaining". There is also a pressure relief valve in the hydrostat that will protect the system if the pressure builds beyond the relief setting. You could be hearing some pressure relief.
The normal whine of a hydrostat is just the machine doing what it does, create fluid pressure and turn in into rotational enengy. There are losses in the system, some of which is vibrational, or the whining.
I've now shared the best expanation anyone has given me to the same question. ....
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Add Photob2910 hyd noise in high gear
| beagle
Join Date: Jan 2004 Posts: 1333 Michigan
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2004-11-11 100220
By the way, "squeeling" is almost always a pressure releif valve doing it's thing. If it squeels during normal use, you may have a relief valve setting in the hydrostat that needs adjustment. ....
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Add Photob2910 hyd noise in high gear
 | Billy
Join Date: Oct 1999 Posts: 975 Southeast Oklahoma
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2004-11-11 100222
Bob, could this sound be a more distinctive (higher pitch) whine when in high range? I know you said high gear but making sure you didn't mean high range.
All tractors I've been around make more of a whine when in high range. The faster you go, the more whine.
If it's still a screaming or ringing and coming from the front, it's not gear whine. ....
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Add Photob2910 hyd noise in high gear
| ampebob
Join Date: Oct 2004 Posts: 16 piedmont ohio
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2004-11-12 100256
Yes the noise only occurs in high range. It does not always happen and may start while just running along. Seems like it could be hydraulic/pressure valve related. The tranny is full.
Bob ....
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Add Photob2910 hyd noise in high gear
| beagle
Join Date: Jan 2004 Posts: 1333 Michigan
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2004-11-12 100261
With over 300 hrs. on the tractor, have you noticed any difference since the tractor was new, or has it always sounded this way. When I went from my first gear tractor to a hydrostat, I was a little bothered by the whining. That was a two range hydro with louder whining in high range. It also squalked, which was a pressure compensator doinf it's thing. Now with the 7800, I have noticeable hydrostat whine it high range, especcialy at higher speeds, towing something, or on grades.
If you have noticed a difference and the whine is getting worse, it could be an indication of a problem.
Try to isolate where the whine originates, front axle, trans., etc. If it's definitely from the front axle, you may have a bearing or gear alignment problem. If you can isolate to the hydro. transmission, is it a whine that is progressively getting louder? If so, you could have a restriction somewhere in the hydrostatic drive loop. Also, what hydraulic fluid are you using? Different hydro fluids could also lead to performance problems in the trans. Stick with the Super UDT if you haven't already.
Hope this somehow helps. ....
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Add Photob2910 hyd noise in high gear
| ampebob
Join Date: Oct 2004 Posts: 16 piedmont ohio
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2004-11-12 100265
Well the noise has always been there. I did change hydraulic oil at 50 and 200 hours (and filters). Went with industrial oil per my dealer. This weekend I will be changing out the fluid with super UDT.
Another question--My dealer suggests UDT for the front axle case--Any opinions?? ....
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Add Photob2910 hyd noise in high gear
 | DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada
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2004-11-12 100267
At some point you will have to conclude that the factory engineers know what they are doing.
I believe the owners manual has the correct recommendations in it, and I would follow it.
I suspect you will see/hear a difference with the Super UDT. Keep us posted on what you find out. ....
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Add Photob2910 hyd noise in high gear
| beagle
Join Date: Jan 2004 Posts: 1333 Michigan
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2004-11-12 100268
The manual recommends super UDT for the front axle case. The give an option for 80 or 90 wght, but I would stick with the Super UDT. ....
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Add Photob2910 hyd noise in high gear
| beagle
Join Date: Jan 2004 Posts: 1333 Michigan
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2004-11-12 100270
I would bet that using Super UDT will make a difference in the performance of your hydrostat. There are differences in the viscosities of hydraulic oils that can make a significant difference in your hydro pump performance. Let us know if that quiets your whining. ....
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Add Photob2910 hyd noise in high gear
| texbaylea
Join Date: Feb 2004 Posts: 51 Brazos County, Texas
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2004-11-13 100296
A comment: Every 4wd piece of equipment that I have dealt with tell you not to operate in 4wd on dry payment or hard surfaces. The front - rear ratios are never perfect due to tire inflation and wear differences plus turns. The torque variations put extra loads on bearings and gears.
Vernon
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Add Photob2910 hyd noise in high gear
| Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2004-11-15 100350
I like the UDT in the axles as long as it will hold it without seepage. I recommend changing to the 80-90 when there is a seepage problem without the time to pull the spindles apart to clean the seals to stop the weeping. ....
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