Kubota B7100 front pto jumps out of gear

[Bluelick]

Hi,
I am the new owner of a Kubota B7100 HST-E, two wheel drive hydrostatic, with a 60 inch MMM. Tractor is about a 1982, has 1180 showing on the clock but clock seems to not work.

Was mowing last night, only the second time I've used it, a field that has not been mowed this summer. Really more of a bush hog job than MMM, so I kept the deck high and went slow. However, the front pto driving the MMM kept jumping out of gear. I found I could drive with my left foot on the pto control lever and hold it in gear.

I did not have the same problem when mowing light grass on Saturday (the only other mowing I've done so far).

Questions:
1. Has anyone encountered this problem?
2. Is it possible that this is a normal sort of fail-safe just letting me know I'm pushing the pto too hard, or is it indicative of a mechanical problem?
3. If I rig a bungie or a wire to hold it in gear, will I be making things worse by continuing to use it this way?
4. If a repair is indicated, is there a source for the internal parts that would be involved?

Many thanks in advance for any help you can offer. I have a fair amount of mechanical experience, keeping my lawnmowers, chainsaws, mowers, outboards, cars and trucks running for several decades, but this is my first tractor and first diesel, so I really appreciate this site.

 

[Bluelick]

Follow up: I mowed some tonight on normal "lawn" and didn't have the mower pto jump out of gear. So, it does seem to be load related. If this was a Mercury outboard motor I'd know exactly what is causing this but tractors are new to me. Now how about somebody who knows these Kubotas inside out?

 

[banjodunn]

G'day i think you have just answered your own question prob too much load


Jon

 

[Bluelick]

Thanks for your reply, Jon. It certainly does seem to correlate with too much load, I guess what I'm wondering is if that is normal, or whether it indicates some internal wear that will be a problem.

If this was a Mercury outboard, something I'm more familiar with, this would be a symptom of wear on the clutch dog teeth from being eased into gear too slowly, and the tranny should not jump out of gear regardless of the load, and it will get progressively worse. But this ain't no outboard, so I'm hoping to learn from the more experienced folks here whether this is normal or not in the Kubota.

Also, I am wondering if holding it in gear under heavy load conditions is likely to cause other problems.

I appreciate this board and the help I've been getting here as a new tractor owner!

 

[charlz]

I don't think it is a 'gear' per se on the older b7100's. My impression was the front PTO drive is accomplished via an electric more maybe mechanical clutch. I believe the front PTO is actually straight off the crankshaft.

 

[Bluelick]

After getting tired of mowing with my foot on the PTO lever to keep it from jumping out of gear in high grass, I rigged up a wire loop that slips over the lever to hold it in gear (see pictures). Worked just fine mowing for a couple hours yesterday in very tall grass (second mowing this year on that field). I'd still be interested to hear if others have encountered this problem or if anyone has been inside of this and has a sense of how far into the tranny I'd have to go to replace whatever is causing this.

By the way, I should have identified this as being the "mid PTO" rather than the "front PTO." When I wrote the original post I was not aware of the other PTO on the front of the engine that does seem to run right off of the crankshaft. The mid PTO, which drives the MMM, is engaged and disengaged with the clutch pedal, which is mechanical, not electric.