Hydrostatic Transmission help

   / Hydrostatic Transmission help #1  

fireman649

Member
Joined
Feb 22, 2005
Messages
32
Location
Port St. Lucie, Florida
Tractor
Kubota B7100HST Diesel 4x4
I just purchased a kubota B7100 hst 4x4 diesel. I t only moves in low gear but not powerful enough to climb a trailer. I just changed both filters on the side of the trans and the one on the top, refilled with kubota udt fluid, and it still doesn't move in high and does do a little better in low, but not much. Do you have to bleed out air after refill, if so, where at? Any help would be appreciated, thanks.
 
   / Hydrostatic Transmission help #3  
You didn't say if this was your first hst tractor or not. If it is, when you push the pedal down it is like going to a higher gear. If you let it up some, it is like down gearing. It is not an accelerator pedal. Sorry if you knew this already, there has been several that didn't in the past.
 
   / Hydrostatic Transmission help #4  
Fireman,

When you change the fluid and filters, you should let the tractor idle for about 15 minutes before you try to move the tractor. I can't remember what the manual for my B7100 says, but I think that it is about 15 minutes. This purges the air from the system. Once you have done that, check the fluid level and top off as necessar.

Best of Luck. the little B7100 is a tough little tractor.
 
   / Hydrostatic Transmission help #5  
Fireman,

Holzster's point about the fuel filter is a good one.

What is the engine doing when you are having trouble moving? Do you lose any RPMs?

I had a problem with my fuel filter where sometimes the tractor would have power and other times it would lose power so bad I had to stop and let the engine pick up RPM again (HST Kubota B2910). It turned out to be the fuel filter being clogged up.

The key seemed in my case to be lack of fuel, which led to lack of power, causing a drop of engine RPM and loss of ability to move/do work.

If your engine is running strong and the tractor is not moving, it's probably not a fuel supply issue.

Are you able to coast the tractor on a slope? Chucko's comment [edit: Now where did I see that comment??? Must be another similar thread around... /forums/images/graemlins/confused.gif /forums/images/graemlins/blush.gif] about the brake is interesting. You probably don't have the brake set, but did the tractor sit a long time before you bought it? I don't know if brakes can freeze like clutches can over time...just a thought...
 
   / Hydrostatic Transmission help
  • Thread Starter
#6  
I just changed the fuel filter as I was changing the hydro fluid. Ther brake is not set. I understand how a hst works, but the problem is it does not move at all in high gear, it acts like it's trying, but won't move. In low gear, it will move fine on level ground, but if you try to go up a hill or dig into a pile , as soon as it hits resistance it just stops were it is.
 
   / Hydrostatic Transmission help #7  
It is likely air in the fuel system. Some one familiar with your model can tell you how to bled it.
 
   / Hydrostatic Transmission help #8  
I'd suspect the relief valve for the hydro is bad. I don't have a clue where it is on that tractor. Good Luck,
 
   / Hydrostatic Transmission help #9  
Go to Tractor Smart and see about downloading the parts manual, it's free, you may need their assitance. It can help identify any part(s) you might need and you can order them there. Ask for some advice as well, they are great!
 
   / Hydrostatic Transmission help #10  
Was it working before you changed the oil and filters? How many hours are on the tractor? did you buy from a dealer?Check the HST linkage, Then check the pressures on the HST.
 
 
Top