replace a 5 inch cylinder with a 4 inch on log loader

[quietrangr]

I have a bad jib cylinder on a Serco 4000 log loader, leaks down and fusses going up. But there is a big price jump between 4 inch and 5 inch cylinders at Surplus Center. I've never had bigger than a 4 inch on other loaders, (these are for the smaller loaders on forwarders), so am looking into dropping down a size. It's a 17 foot boom. What do you think?

 

[Rustyiron]

Is re-packing your 5" out of the question? It should save you a good bit of money if you can.

 

[Arc weld]

Look into to repairing your existing cylinder first. It's likely a way better cylinder than one from Surplus center. It might just need new seals and/or honing. A 5" bore cylinder has over 17,600 lbs.(8.8 tons) more force at 2500 PSI. That's a big difference!

 

[quietrangr]

You guys are right on both counts as to quality and force, but the cylinder is likely about 25 years old and I suspect problems with the hard parts. Had one rebuilt once, and it lasted a year, then had to buy a new one anyway. Also, would the 4 inch be faster?

 

[Arc weld]

1991 isn't that old for a cylinder. Take your cylinder apart and there's a good chance the seals can be matched up and it can rebuilt. Your machine was designed for a 5" cylinder, why change that? Of course a 4" would be faster but again, why not take the one you have apart and see what you have.

 

[farm boy00]

Don't know what the insides of a cylinder look like but I would say screw it and tear it apart and see what can be done. To me it's always a learning experience and if you can patch it up for a few years you might have more money later on for the proper cylinder

 

[Arc weld]

Cylinders can last decades and decades. Proper seals and assembly, if there's no other damage or abuse abuse the cylinder will be good as new.

 

[muddstopper]

I agree with rebuild before replace. I have seen seal packs for large cyl for as little as $60. Not saying thats what yours would cost, but certainly worth checking into. Unless the shaft is bent, theres a very good possibility that a few piston seals and the shaft seal are all you need. also, going from a 5in cyl to a 4in is going to cause a 20% reduction in lift capacity. Unless you never pick up any where near the current lift capacity, you might not be able to pick up what you need to when you need to. we have run rebuilt cyls at work for years, I have some 6in ones that where rebuilt back in 1989 that see tons of work every day with nary a leak, yet, knock on wood:banghead:

 

[quietrangr]

OK, you guys convinced me. I'll check into rebuilding. Thanks a lot to all of you.

 

[muddstopper]

Not knowing your cyl design I'll give one warning about building it yourself. If the pin end of your shaft is welded on, you will have to take the piston off the other end to replace the shaft seal. Now I have seen a few where the nut would come off with a lot of grunting and I have seen some that needsed heat to break them loose. If those nuts use plastic inside for locking, be very careful with the heat. You melt the plastic out and you will have to replace the nut. I had a kumatsu loader that leaked a stream around the shaft. I think the rebuilt kit back then was around $30 or so. I had a long bar thru the pin hole on the opposite end of the shaft to keep it from turning, and a 24" cresent on the nut, followed up with a long piece of pipe. Try as I might, that nut wouldnt come off. Put the heat to it to get it off. Ended up having to replace the nut and Kumatsu charged me $60 for just the nut.