I bought a Hopto 500 about 4 years ago to play around with on my farm. It ran pretty well for the few things I wanted to do with it. This past week I got it out to clear some trees out of an old fence line. It was working fine for about ten minutes and then the undercarriage drive system stopped working correctly. For those unfamiliar with the drive of the Hopto, it has a single lever that controls the undercarriage. You push it forward to go forward and pull back to go backwards. Mounted on the lever are two air valves. When you purge the right valve the right track is not supposed to move and vice versa. When I went to run it a few days ago both tracks seemed to move no matter if I had purged the valves or not. I used the boom to lift up either track from the ground. After doing some testing I discovered that the air valves were still working in that only the track that was supposed to move would run when I lifted it up off the ground. The only thing that I could think of is that there is supposed to be some sort of brake to hold the track from moving that is on the side with the purged air valve. I am at a complete loss and don't know what to start looking for. Any help would be appreciated.
I may have some info on that undercarriage, but the info is in Ohio, I am in Finland.......if you can wait until first week of September.....
As I recall from working on one thirty years or so ago, the air can works a dog clutch, when trying to turn while travelling, it's best to flip the air valve, then stop and change direction for just a bit to release pressure on the dog clutch and it will pop out (the machine we were working on had set for years, everything was sticky) and I believe there was a spring loaded brake that came on under there somewhere. These not only require fiddly adjusting but were also prone to oil soaking so they tended to slip. Of course I may be hallucinating too, as I said it's been decades. I do remember though that if you were travelling and flipped one valve or the other it would continue merrily until you reversed course for a second to get slack enough for that track to disengage. Sometimes when it was cold out, it took more than one try? Oh, I think they were two speed also? Slow and glacial? May be wrong about that too.... Spent two weeks repairing the tracks as even then they were unobtanium.
Lantraxco Your memory is correct. I dropped the pans under the drive gears and everything was just like you said. The brake pads seemed loose and they were covered in hydraulic oil. I took the pin out of bottom brake pad and cleaned it the best I could. Reattached and tightened up clearance. I also tightened the springs on front of undercarriage that I believe create the tension for the brakes. Got everything back together and I can turn again. Thanks for the advice. Ps. You are correct about it being awfully slow. Not sure abouto it having two speeds. Haven't found anything that would change speeds but now that you mention it I will look for that possibility
Good to hear that you got it going and even better that you reported back on what it was. Somewhere down the road that now written knowledge will help someone else. Post a few pictures when you can. You might need three posts first so you are close. Lantraxco, Your memory is great. To remember the details that long ago means the job was either a real pleasure or a real pain. LOL
I thought I had some pictures on my phone of the old girl but I don't. Will have to take some this week while in use. Should have taken a couple while I had the pans off. Pretty cool system actually
OIH, like you I have always enjoyed old iron, and as a young man in my twenties just learning a trade it was a pleasure working on machines that even then were obsolete and "old tech" This Hopto was at the beginning of hydraulic excavators I think, one of the machines with hydraulic upper bolted onto an existing design crane lower. Had the flat crane style cast track pads and the drive as I recall was a single hydraulic motor ABOVE the swing bearing, mechanical shaft transmitting power to the lower unit. See? Must have made quite an impression on me, lol. jsp4bucks, that's great, I'm not at all sure on the two speed, might have it confused with another machine. I seem to recall a mechanical linkage that actually shifted a gear in the reduction that the hydraulic motor bolts into, or went down through the center shaft of the machine but again might be hallucinating? Do you have to dance like Fred Astaire to run that machine, one stick each for boom and stick, side to side foot pedals for bucket and swing? That's how I remember it.
You are dead on on all the controls. Three sticks between your legs and one set of pedals for each foot. Third stick is tracks with air switches. What I really need for it is a skinny bucket. Something like 15 inches or so. The only bucket I have is like a 42 in ditch dipping bucket. Makes it hard to work with. If you remember all this just from working on one thirty years ago you definetly have a great memory.
Can't remember what I had for lunch yesterday though! LOL... Sounds like the same machine it had a wide bucket on it too. Shouldn't be hard to adapt one from another machine, but I would think a two footer would be about as narrow as it would comfortably take due to the width of the stick?