755 PTO Clutch

[unimog_jason]

Hello Everyone,

I recently picked up a 755 and everything looks to be pretty decent with it, needs a little TLC here and there but over all I'm happy with my purchase.

One thing that has me a little concerned is the PTO clutch, it's a little tricky to get it engaged sometimes. The symptoms are:

- Slide the lever to the top and you hear the engine lug down a little, but the snow blower doesn't turn.

- Slide the lever to the top and wait a moment and the PTO engages smoothly and I'm able to blow snow without a problem.

- Sometimes I get the PTO spinning but as soon as I take my hand off the lever the PTO stops.

The last symptom started after I lubed up all the linkages, the previous owner didn't seem to be too concerned with preventive maintenance so I'm guessing the lube loosened things up a little too much.

While I was inspecting the tractor I noticed that someone wrapped wire around the PTO lever and the arm with the magnet on it. My hope is that there is something wrong with the lever mechanism or the linkage to the transmission needs adjusting and not something else like a clutch pack rebuild.

I have a service manual on order but me concern is that if the lever or linkage is out of adjustment I might only be half engaging the clutch pack and that can't be good.

If anyone has any insights into what could be happening here please let me know.

Thanks,

Jason

 

[unimog_jason]

Just a follow up to the initial post. I went to the JD parts site and found the picture for the lever and linkage and attached it to the post.

Parts 2 and 8 have wire wrapped around them so that when you push the lever up it pulls the second lever with it. I assume part 7 is an electro magnet and part 4 is either a piece of steel or a regular magnet.

Right now there doesn't seem to be any attraction between part 4 and 7 so I assume the electro magnet isn't working. I am going to guess this is the PTO safety switch and when you get off the seat the circuit is broken and the electro magnet disengages and the PTO stops.

I figure the wire that wrapped around 2 and 8 was the previous owners attempt at by passing the safety feature.

What I'll do in the morning is use a screw driver to push lever 8 up and see if the PTO engages every time or if it still acts the same. If things work better I'll try to figure out why the electro magnet isn't getting power.

Jason

 

[unimog_jason]

To close this off in case someone has a similar issue in the future, the entire problem appears to be messed up electrics.

I removed the magnet and put a nylon rip tie in it's place and now I can engage the PTO every time without a problem.

I bench tested the magnet after cleaning up the spade terminals and it now generates enough force that I can't separate the two pieces when I apply power.

I should be able to put everything back to the way it was when it roll out of the factory with a little more cleaning.

Jason

 

[jd110]

Jason, you have a pretty good understanding of how this works. It is tied into the seat switch circuit, but it also has a timer module in the circuit also. There is a delay built in so if you bounce up off the seat momentarily, it wont shut off the pto unless you are off the seat for maybe 3 seconds. I have seen quite a few "bypassed" like you are seeing. Just make sure the wiring to the seat switch, control module and electromagnet is good, and it should work fine. The most frequent problem seems to be the seat switch. The timer module is very reliable.