I dropped my backhoe at a friend's place about 3 weeks ago, so he could use it to dig a trench-When I saw him about a week ago, I asked how it went, and if he was done with it-he said it had worked just fine, then hesitated and told me that it was having problems. I asked what kind of problems, and he said that the day after he finished the trench, he went to move the backhoe, and when he engaged the hydraulics, and started to lift the boom, it made a funny noise, didnâ€™t seem to work as well as it used to, and on further investigation, it was spitting bits of metal out of the area of the PTO and the chain drive for the hydraulic pump.
I wasn't too worried until he also told me that a mutual friend had looked at it, and couldnâ€™t figure out what the problem was. The guy who looked at the tractor can pretty much fix anything, without hardly thinking about it, so then I got worried...
I went over there today(and brought some come-alongs just in case) to see what was up, and if I could fix it or needed to bring it home for repairs.
Well, I took a close look at the situation, and discovered that the teeth on the PTO sprocket were all sheared off(that must have been the â€œspitting metalâ€ source). I also found that it still worked, sort of-we needed to use the come along to raise the main boom, with what little help the hydraulics could give as the sprocket spun inside the chain.
Anyway-I knew teh chain was on the loose side(it had no tensioner, and I suspect it had been lubricated rarely, if at all, before I got it-so I guess the sequence of events was as follows:
The chain was only very infrequently lubricated.
This caused it to stretch.
The stretched chain was causing undue wear on the sprocket teeth, especially near the tips as the stretching caused it to move in and out and rub on the teeth
Eventually, it got long enough, and the teeth got worn enough, that the chain occasionally skipped a tooth.
Then the tips started to get rounded over, and the inevitable happened.
I took it all apart today to figure out what parts I need to get to replace things, and while doing so, I finally got to take the sprocket off of the PTO shaft-when I tried in the past, using a puller, it would not budge. The sprocket was a homemade double-row #50-2 chain sprocket, with only one accessible setscrew, but another setscrew hole in the hub peeking out from under one of teh chainrings. It looked as if someone cobbled it together from some of the "weld-on" sprockets and hubs, but highly modified. I figured maybe there was another setscrew in that hole under the chainring, but after I put the thing in my hydraulic press, it pressed right off. No additional setscrew, just some rust holding it on.
Anyway, I found that the PTO shaft has a 1" diameter, with a groove for a 1/4" key. I can;lt see any evidence of how it was modified, but I guess it must have been welded up and turned to diameter on a lathe. Here's what it looks like:
I just thought some of you might be interested.