Bent bucket cyl on model 48 backhoe

[ptsg]

Looking good. Those bushings are cool. First time I've seen those.

 

[Quebecguy]

Thanks for sharing the info on the bushings. Those might come in handy someday!

 

[jthibodeau89]

Great info on the bushings. They should work just fine. How does the width of the tube on the cylinder base compare to the gap between the the mounting plates on the dipper? The clearance should be on the order of 1mm in order to keep the pin in shear and minimize bending moment.

 

[Quebecguy]

How does the width of the tube on the cylinder base compare to the gap between the the mounting plates on the dipper? The clearance should be on the order of 1mm in order to keep the pin in shear and minimize bending moment.

On mine a 1/8" drill bit fits into the gap (or free play) easily. On the rod end a 3/32" drill bit fits in the gap. I don't know how many hours are on it - perhaps a couple of hundred but the backhoe has been working well since I bought it new in 2006.

 

[DanMc77]

Great info on the bushings. They should work just fine. How does the width of the tube on the cylinder base compare to the gap between the the mounting plates on the dipper? The clearance should be on the order of 1mm in order to keep the pin in shear and minimize bending moment.

At this point I don't have an exact measurement of the gap in the dipper. I haven't pulled the old cylinder body out yet, mostly because I wanted to keep the hoses connected until I'm ready to put the new cylinder in. Your comment of a tight tolerance is a helpful insight, so I'll have to be prepared with some shim washers to tighten it up if needed. Additionally, there could be some error in the alignment of the rod end tube that we had to weld on. I'm inclined to run the machine a little while, then pull the rod pin out and examine the wear patterns. It may be good if there's a little slop at the top, so I can adjust the angle of the cylinder a little, if there are uneven marks left in the pin.

 

[jthibodeau89]

Dan, shims won't help for shear. The gap betweem the solid metal of the mount and the cyl cross tube or rod cross tube is what determines bending vs shear.. If the total gap is over 1/8" (1.5mm/side), you may want to consider flanged bushings to close the gap on the base end. The rod end should be fine since you reused the rod cross tube.

 

[DanMc77]

jthibodeau89: Oh, now I see what you are referring to. I thought you were referring to a potential mis-alignment if the cylinder is skewed at an angle. We will see how it fits and go from there.​

 

[DanMc77]

New pin is done. Rather than drill a hole through the pin, weakening it, I'm using heavy snap rings to keep it in place. Plus, I have no way of knowing exactly where the retainer bolt is, since the machine is in NH. Pin is 4140 annealed. All of the pins that I have dealt with in this machine have been soft. There's 7 1/4+" between the snap rings. The bushings should arrive tomorrow.

 

[DanMc77]

Final status on this project.

I am in love with these spring shims. I ordered several of these of various lengths and ended up using the two longer sizes and cutting them down to length --> 2.13". The shims were tapped into the dipper bores, and then the new cylinder could be installed with the new 1 1/4" upper pin. The cylinder cross tube fit perfectly in the dipper with no adjustments to anything other than the shims.

Once it was installed, I noticed that there was a pretty significant gap on the rod end, as seen in one of the pics. The normal assembly has shim washers under the bolts for the retaining pins, and that helps to reduce this gap, but they are not enough to close this up. A couple shim washers were added to take up this space, so dirt has a little more difficulty getting in there.

Everything works perfectly again. Thanks to everybody that contributed their comments for this project!!!

 

[al20hp]

I just had the same thing happen to my bucket. Bent the dam rod!

I was reading your post .I think I am interested in going in the same direction. One quick question. Instead of putting bushings on the one end, why didn’t you replace that end of the new cylinder with the end from the original JD cylinder ?

Also, do you remember how much of the rod you had to cut off?

Thanks
Al

If I use the first one, the loader cylinder, that has 1 1/4" pins. Couldn't I use a 1 1/4" pin, then machine bushings to fit into the 1 1/2" bores in the dipper?

I've been happy with Magister. Mostly, I like their selection, and the prices are great too.