Almost all implements that have gearboxes have some sort of protection in case something goes wrong. It can be a slip clutch that uses a series of clutch plates and friction to drive the implement, and if an obstruction occurs it "slips" to avoid major damage. A lot of implements just have a little shear pin or shear bolt that is the weak link in the chain. If you hit something you shouldn't, or if there's a catastrophic failure, they're designed to break, thus protecting a more expensive component. That all happened as it should recently on my post hole digger.
I was digging holes for some corner posts and I hit something about two feet below the surface that caught the tip of the auger and didn't move. I'm pretty sure it was a large rock, maybe part of the bedrock. The shear pin gave up its life for the cause when it broke, but it protected the gearbox and the tractor.
I've been pretty fortunate in never having to replace this pin. Where I live there are large amounts of rocks below the soil, but they usually pop right out of the hole when the auger hits them. So, when I started to disassemble the yoke I wasn't completely sure what I'd find.
I first tried to drive the old pin out without removing the yoke that covered it. For that to happen, everything would have to line up perfectly and I knew that was going to be difficult. So, I needed to take the yoke off to expose the shaft that came out of the gearbox. Usually there's a snap ring on the shaft that has to be removed to get the yoke off, this machine didn't have that. There was a little stub bolt with no head, with threads its entire length. I reasoned that the end of it fit into a groove on the shaft to keep the PTO from popping off when the shear pin broke. That's exactly what I found. I located a nut that fit the little stub bolt to use to jam to it, tightened the two together and removed the little stub bolt and the yoke came right off. It wasn't quite as easy as I made it look in the video but I'm not a fast mechanic and I didn't figure you wanted to watch me searching for tools and dropping stuff and not being able to locate it in the barn floor.
I had planned to just slap a low grade bolt in the slot and move forward, but the machine was designed so they could sell you parts for it, and I get that. Had the shear pin been $40 I would have gone to plan B, but it was $3.40 and I can live with that, so I got an extra one to keep in the tractor tool box. It went back together without a hitch and now I can use my post hole digger again.
All total, this little project took eight months. The first day I tried to take everything apart in five minutes and when I couldn't figure it out I gave up. I spent 7 months and 26 days thinking about it and putting it off. Then one day I had to dig a hole by hand and at 3 o'clock that afternoon I had the camera rigged up and was fixing it, determined it was going to happen. It took one day to go to the dealership and get the part and the following day to fix it. Repairs are something I tend to put off until I need the implement and so I get to do them when it's 30 degrees and sleeting with a howling wind. The first day I tried to fix it, it was in the 70's and sunny. You probably don't need to know that, but that's how I roll.
SUPPORT THE TRACTOR MIKE CHANNEL: / tractormike
Visit the Tractor Mike website: asktractormike.com/
Subscribe to RU-vid Channel: ru-vid.com...
Visit Facebook Page: / ask-tractor-mike-31211...
Buy Stuff I Use: www.amazon.com/shop/tractormike
14 дек 2016
