Hydrostatic Transmission help

[fireman649]

I just purchased a B7100 HST 4x4 diesel tractor. It only moved in low gear, but not enough power to climb a trailer. I just changed the filters on both sides of the transmission and the spin on filter on the top. I replaced the fluid with kubota udt, it still does not move in high gear, you can hear it trying to go, and fell it trying, but it won't. It does move better now in low gear, but still not a whole lot of power. The front hydraulics for the bucket work perfectly, the bucket moves in all directions without any jerking, and the pto and 3 point all work correctly. Any help would be greatly appreciated. Is there a bleeder valve to bleed air out after filling? I jacked up the rear and ran it, and all seems fine, but put it on the ground in high and it won't move. Thanks in advance. Also, the filters on the sides were quite dirty.

 

[hwp]

Hello Firemen649 and welcome to TBN. It would be helpful to most TBNers for you to fill in your bio so that we have a better idea of where you fit into the grander scheme of things. I don't know how familiar you are with hydrostatic transmissions but this is one area where less equals more - by that I mean that less pedal equals more torque and vice-versa. So if you want the most torque but not much speed then just ease the pedal down a bit. If you want high speed and low torque, put the pedal to the metal. Most Kubota reference manuals have good descriptions and diagrams of how hydrostatic transmissions work. My F2400 will not climb major hills in high range but will go almost anywhere in low range. Is this the kind of problem you ar having or is it something more specific? /forums/images/graemlins/smile.gif

 

[B2400]

Even in high range your 7100 should easily climb up on a trailer. I have a steep draw in my backyard that was mowed in high and tractor barely slowed for it.
Your bucket and three point hydraulics are semi independent of the hydro. The main hydraulic pump only supplys flow for the charge pump on the hydro which in turn provides the oil for the multi piston pumps for the drive and driven side of the hydro. It sounds as though you may have a relief valve for the hydro unit stuck. Does it act the same in forward and reverse? Might be time to have a Kub mechanic give it a little diagnostic time( Yeah, I know, EXPENSIVE but the best way to get to the heart of the problem if nothing simple fixes it!)

 

[JimMorrissey]

I'd say take it to a dealer for a look, and the sooner the better from the sounds of it. You could be doing more damage by trying to run it in a high gear.

You did what you can easily do by changing the filters and hydro oil. Now it's time for somebody who knows what they're doing to have a look.

 

[chucko]

parking break on? Don't laugh I have done it

 

[btolle]

</font><font color="blue" class="small">( parking break on? Don't laugh I have done it )</font>

I have done it MANY times! If I don't have it set hard I can drive with it on but am really short on power. Did it on my B7100 and still doing it on the B7510.

Wonder if he drove it before he bought it? If he did and it pulled OK then it is most likely the parking brake.

Bill Tolle

 

[OrangeGuy]

How much free travel on your clutch pedal? Should be 3/4 to 1 1/4". If tight, you may have to adjust. Your clutch may be slipping.

OrangeGuy

 

[fireman649]

That's what I strted to think last night, about the clutch maybe slipping, have to work tomorrow, so I'll check it on Friday. The parking brake is not set. I understand about how the hst works and about the pedal, but thats not the problem. In high gear, it does not move at all, it tries, but nothing. In low gear, it moves fine on level ground, but going up a little hill or digging into a pile it stops as soon a sit hits any resistance. Thanks for the replies.

 

[tractorman]

If there is someone that can help you for a minute, engage the PTO and make your tractor bog down, if your tractor stops moving and your pto stops as well then your problem is the clutch. That is the most likely scenario. Good Luck, Tractorman

 

[pcwayne]

You might want to check for a partial clogged exhaust. It's one of the most difficult problems to diagnose since everything runs fine on level ground till you hit a resistance like a hill or a load. Then the power level drops 10 fold. Easiest way I've discovered is to partially disconnect the exhaust manifold so exhaust gases are unrestricted and then road test (may be a little loud). If it climbs the trailer then viola! Most common cause is a baffle within the exhaust system has broken off and is restricting the flow of exhaust. Sometimes the inner layer of the laminated exhaust pipe separates and folds. Don't operate unit with a separated exhaust over a prolong period or you may develop other serious problems, such as a warpped exhaust valve. It's for testing only and should be sealed back after the road test.

 

[_RaT_]

I've forgotten now if you mentioned if the engine loads up when you test the two ranges. If it is loading up, I would say it is not the clutch. The clutch on a hydrostatic really doesn't wear out unless the previous operator used it improperly which would be kind of tough to do. The brakes don't wear out either.

 

[chucko]

Could something have wedged in somewhere under the tractor and hung the break up or bent a break rod or something?

 

[ramon49]

Sure it's not a L3130????

 

[_RaT_]

Ramon. SELL, SELL, SELL... You'll never get a better value for it then right now. Keep the hoe and get a L5030 and you will only be less then satisfied with it's power.

 

[ramon49]

Check the fuel flow - filter or change it. Restricted fuel flow when you call for more power! Watch the bowl empty and this is your problem.. My 2 cents! Been collecting soda bottles to save for my new 5030 !!!!

 

[_RaT_]

Are they still .03 cents refund? That was my passion back in the 60's. I'd save up all year and then we would go to Stinson Beach for 2 weeks of pure heaven. The coke bottles got me candy at the local grocery store. Back then, Cracker Jacks were a dime, everything else was a nickel. Life was good!

 

[fireman649]

I've already changed the fuel filter for it's normal service. The tractor does not have a power issue, the trans is reaching too high of pressure and dumping fluid back into the reserve tank from what I understand. When this happens, the motor does not bog down.

 

[_RaT_]

That's what I recall you mentioning or the way I understood it anyway. Plenty of engine, just simply a HST issue in my judgement. If it was the clutch slipping so badly, surely you would at least smell it.

 

[fireman649]

Well, I got it back from the shop the other day, $2,600 later and it runs great. The hydro pump went bad, wasn't producing near the pressure it should have. Also got the clutch replaced while they had it split, it was getting low. I didn't expect this little machine to have so much power, I'm impressed. Thanks to everyone that posted there ideas and information.

Steve

 

[grandad]

Fireman, do you have any idea how many hours are on your 7100 or what it was used for in it's previous life? There have been endless debates here on TBN about the longevity of the HST transmissions. You are the first one I've read who actually had yours go bad and ponied up to replace it.