2009 Bobcat E60

[Welder Dave]

We're the original pins left to turn in the lugs? Seems stupid if they were but wouldn't be too hard to modify. Would be a lot less than expander pins.

 

[materthegreater]

The only rotational movement is between the pin and bushing. The expander pins eliminate wear from the pins moving slightly in the slip fit clearance of the lugs.

 

[Welder Dave]

A lot of pins have an ear welded on and a bolt to hold the pin in and prevent it from turning. I know someone with a farm loader on their tractor that the pins just have a circlip or hair pin on each end of the pin. They don't grease it enough but even if the did the pin is free to rotate. The holes in the stationary lugs are badly worn because of such a terrible design. I've seen pins held stationary badly grooved and worn out in the section where something turns on them but like new on the ends in the stationary lugs. The lugs had no wear either. I think proper pin retention, thick enough mounting ears and proper greasing should last for thousands of hours and the life of the machine in a lot of cases. The torque arm on the rotary cylinder of my backhoe uses a type of expander pins. I think just to keep everything as solid as possible. Nothing turns. The torque arm is about a 2" thick square solid steel bar with holes in each end. I think the holes are about 1 1/4". The mounting lugs have the holes tapered to fit tapered end caps of the pin. The end caps are also tapered on the inside to fit the end taper of the pins. When both sides of the pins are tightened everything is wedged solid. It took a while to figure out how to get the pins out. You have to remove the nuts on each end and take the end caps off in order to get the pin out.

 

[materthegreater]

Most of these had a retaining sleeve with through bolt. There's still a small amount of movement that can happen and after 5000 hours lugs get worn. The stationary lugs do not have a provision for greasing since they aren't a rotating joint. Wear is just what happens when you have slip fit clearances. Expander pins eliminate the need to have the lugs welded and bored, and provide a completely tight fit. At some point I'm going to do the cylinder pin joints also. Especially the arm cylinder, it sees the most load cycles of all. Just the 4 expander pins that I installed last year made a big difference in how tight the machine is.

 

[Welder Dave]

What did the expander pins cost? Nord Lock is good stuff but a little pricey. I bought 40 1" Nord Lock washers for my grader wheel adapters and they cost $250. The 5/8" were much more reasonable.

 

[materthegreater]

Less than it would have cost to have them all welded and bored. And the end result is tighter.

 

[Welder Dave]

Too much to post?

 

[materthegreater]

More like too much to remember off the top of my head.

 

[materthegreater]

I think the the 90mm ones were $8-900 each, and the smaller ones were somewhere around $4-500. But that was quite a while ago so I could be off by a hundred or so.

 

[Welder Dave]

Pretty pricey for most people but I guess if they eliminate wear are worth considering.

 

[materthegreater]

Well this cylinder is a bit different than others I've done.






Hoping to finish it up this afternoon.

 

[Welder Dave]

Looks like someone beat on the piston in the last pic.

 

[Swetz]

Most of the cylinders that I have rebuilt for electric utility work (diggers and bucket trucks) had nuts. It seems that most backhoes have bolts. Not sure how much it matters, mut I have seen more than one nut with a set screw in it. Most of the nuts I have seen were regular hex elastic stop nuts that we replaced upon rebuild.

 

[materthegreater]

Looks like someone beat on the piston in the last pic.

There's a dent at the very base end of the barrel from it's days as a rental machine before I got it. What you are seeing is a slight deformation from being retracted to the dent. I filed and polished the deformation so it doesn't affect the new seals. In all the years I've had this machine, I've not encountered a situation where the boom goes low enough for the piston to get to the dent, so I'm confident it won't cause any issues.

 

[materthegreater]

Most of the cylinders that I have rebuilt for electric utility work (diggers and bucket trucks) had nuts. It seems that most backhoes have bolts. Not sure how much it matters, mut I have seen more than one nut with a set screw in it. Most of the nuts I have seen were regular hex elastic stop nuts that we replaced upon rebuild.

Most others I've done have had a bolt or just a nylock nut. I've never seen one before where the piston threaded onto the rod. This is the first cushioned cylinder I've had apart also. Neat to see how that works.

 

[materthegreater]

I got the arm cylinder apart last night. This one is cushioned on both ends of the stroke. The piston was loose on the rod and the lock nut was loose also, with the set screw being the only thing keeping it from coming all the way off. I find it odd that the service manual doesn't give a torque spec for the piston or the lock nut.

 

[Swetz]

The piston was loose on the rod and the lock nut was loose also, with the set screw being the only thing keeping it from coming all the way off

I am thinking thread locker.

 

[materthegreater]

I torqued the pistons to 300+ and the lock nuts to two grunts with the pipe wrench. There was no evidence of thread locker on them originally so I didn't think that was a good idea. It's just odd how silent the service manual is about tightening.

 

[materthegreater]

I wish dental insurance would cover this...





I should at least get dentist assistant wage for this.

 

[Welder Dave]

Electric shock treatment?