ARPS Backhoe swing chain repair

[Brad_Blazer]

I was digging out a little tree and managed to break the swing chain on my backhoe. Where the chain pins to the boom, the 9/16 link pin had a bushing on it to fit the hole in the boom which was about 0.82". The pin and bushing were hard but the hole in the boom is not. The bushed diameter should be enough to spread the load. The problem is that the bushing is not very thick and the pin was able to flex enough to crack the bushing. The hole then deformed and the pin cracked in two. I ordered a heavy duty repair link from McMaster along with some 9/16 and 7/8" W1 drill rod material. My first thought was to bore the hole out to 7/8" and make a bushing out of the larger drill rod. I was still worried about how the original bushing cracked so I decided instead to make a 1-piece fat pin by just turning down the ends of the 7/8" material. I left a radius at the base of the neck to hopefully prevent cracking. I made the new pins and then hardened them by heating to orange with the weed burner torch and quenching in water. Then I tempered them by re-heating to about 500F measured by my IR thermometer and let them slowly cool in air. I did the file test and they seemed to get nice and hard.



In these 3 pics you can see how the pins fit and how the chain attaches. This was actually earlier this summer. This past weekend I put the backhoe on for a small job and of course the other side broke so I got to repeat the repair. So far so good. The 1-piece fat pins should be much more rigid than the standard bushed pins and I'm hoping for no more problems. I never did use the new link I ordered. The 12" piece of 7/8" drill rod and the 36" piece of 9/16" drill rod were about $10/each.

 

[Treemonkey1000]

Nice work! That is a honking big chain

 

[Farmerford]

Nice work!

How did you bore the hole out to 7/8" with the piece still on the machine?

 

[Brad_Blazer]

Thanks for the comments guys!

Nice work!

How did you bore the hole out to 7/8" with the piece still on the machine?

Good question.
I rigged this up - sorry about the blurry pic. I made an aluminum guide plug for the far end and used an annular cutter with a spring-loaded guide pin that engaged the guide plug. Then I clamped the whole thing to the backhoe and turned the cutter with a wrench.



On the second one I just turned the pin down to fit

 

[mostly_gas]

Nice work :thumbsup: Drill rod is O-1 tool steel if I recall correctly. You can use an oil quench and reduce the chance of cracking while hardening.

 

[dfkrug]

I made an aluminum guide plug for the far end and used an annular cutter with a spring-loaded guide pin that engaged the guide plug. Then I clamped the whole thing to the backhoe and turned the cutter with a wrench.

Very innovative, Brad. Don't you love those annular cutters? I will have
to try something like you did next time I run into that kind of situation.

 

[Brad_Blazer]

Nice work :thumbsup: Drill rod is O-1 tool steel if I recall correctly. You can use an oil quench and reduce the chance of cracking while hardening.

McMaster sells drill rod in many grades of steel. I just bought the W-1 because water is easy and clean. They have pretty fine diameter increments which is nice if you need custom pins or whatever.
McMaster-Carr

It's funny I snagged the annular cutters out of a dumpster and they are still sharp! The guide pin is a 1/4" transfer punch from a cheap Harbor Freight set.

 

[Taylortractornut]

Brad I wished I d have caught this post a bit sooner I have some extra links the next sized ARPS under mine. Ive still got to do something with mine a man that bought it from me and put it on a too small of a tractor hnnaway and bent the swinging seat mounts. He brought it back and gave it to me.

 

[Brad_Blazer]

My fault - I posted it after the fact. I actually ended up not even using the link I ordered.

Did that bent cylinder on yours get replaced? All you need is a sturdy machine to mount that thing on. I guess it's hard to find motivation when you already have a backhoe. How about a forwarding trailer or barge?

 

[Taylortractornut]

I had gotten some largers cylinders at an auctuon and the man that bought it said he bought it for them after he brought it back. Seems he tried to back down a hill without enough weight o nthe front end and too small of a tractor. He also robbed the radius arm off of the bucket. I have the old one to make a new pattern from. Im going to find some better matched cylinders. I want a forwarding trailer. It woul be better suited to raise the boom pivot higher to make an above grade machine. I thought about making a bypass grapple with a dangle head and selling it the sale but I may make a forwarder trailer maybe make it to bolt to the frame of a walking beam trailer for loading logs and stone.

I did see an old IHC industrial backhoe mounted between pontoons on a slide system to make a small dredger for lakes. If I had an extra 2 ton bob truck like a trailer tote I d put in on back as a high speed backhoe for light jobs.