CAT Hydraulic Cylinder - reseal

[alrman]

Just a question for you guys who regularly work on CAT equipment.

I resealed some cyls on an old loader some time back & found difficulty doing the job & thought it was just 'old technology' or maybe the rods may have been changed.
I recently resealed a dipper cyl on a 432D & found same issue.

When you have resealed the gland & go to slide it back onto the rod, there is no lead / chamfer on the end of the rod to allow the wiper/dust seal to slide on the rod without any damage to the seal.

Is there a tool that slides on to the machined stud to guide / expand the seal onto the rod?
If not, how do you guys fit these glands to the rods?

I have resealed hundreds of cyls before - Case, Yanmar, Hitachi etc - only come across this on Cat. :beatsme

 

[jrtraderny]

The Cat's I've done have had a chamfer on the rod.
jr

 

[Per Eriksson]

There are tooling avaliable, it's just cones/collars so it's easy to make one yourself.

Or grind a chamfer as needed.

 

[Nige]

A lot of Cat rods by design can't have a chamfer on the end because the piston butts up to that corner. If there was a chamfer on the rod the piston would not have 100% support.

There are special tools for the job. They are called "Rod installers". The downside is that pretty much every rod needs a different part number of tool. I found that a single wrap of heavy electrical tape (with a smooth outer surface) round the end of the rod, then well lubed with hydraulic oil gets the wiper seal on OK.

 

[hotsaw]

Sometimes it helps to rotate the gland as you are starting the dirst seal.

How do you press seals back down to size on a swivel piston? They send a plastic strip along with te seal kit which I pressed with a big hose clamp but it still makes marks on the seal. Is there a tool to press them on right?
THanks

 

[willie59]

I've had a machinist turn a piece of round stock in a lathe the size of the rod, turn a good chamfer on one end, square edge on opposite end, the bore hole in the center the size of the bolt that hold the piston on the rod. Use bolt to secure to the end of the rod and you now have a tool that will slip the wiper and the rod seal over the squared end of the rod without damage.


hotsaw, I use an automotive type ring compressor to press piston seals that are stretched during installation back to size.

 

[alrman]

All these sugestions are great in a workshop situation - but, when doing a repair in the field & customer is watching, other workers waiting for machine to get going, there is no time to fabricate collars etc.
Some guys, well, they just don't like to see you pull out a grinder & put a bevel on his rod that was assembled by someone else without having to do the same...........

 

[jrtraderny]

Lots of times I'll work the wiper on the rod without the gland then install gland and then drive the wiper in with a brass drift. That way you can use a piece of feeler stock to keep the wiper from getting cut on the edge.
jr

 

[Jam]

Use a engine piston ring compressor if things are stubborn. They are cheap and work well with plenty of oil.

 

[HeavyMan]

I have a couple of pointers for to help you get the job done fast and without damaging the components of the cylinder. First, CAT rods are designed to have a small chamfer on them and I have ran into the same issue as everyone else. At the shop or out in the feild I use a 1/4 die grinder with a 80 to 120 grit flap wheel to remove the sharp edges on the exsiting CAT chamfer. Next I have a few different techniques depending on the size of the gland;
if you can start the wiper, twist while pushing the gland on to the rod. if you can't turn the gland easily I use a piece of honed tubing, again depending on the size of the rod to put between the gland and the nut, turn the nut on to the rod which pushes the tube into gland and onto the rod. most nuts are 4'' so large 1'' socket with ratchet no impact gun. if you have a helper you or he could hold the tubing and you hammer the tube into the gland with block of wood. I use a large dead blow Not sledge but the same size.
If you can't start the wiper use a piece of shim stock. wrape it around the rod and overlap about 3/8 then cut to length, make sure the shim over hanges the chamfer just enough to start the wiper, DO NOT push the rod seal over the shim it may cut the ucup, as you get wiper started twist the gland while turning and pulling the shim out. make sure all the shim is accounted for.

 

[HeavyMan]

For Piston seals that you have to be stretched on the piston and compressed back or even the cemcast piston seals, I use a hydraulic ''wear ring'' and put it around the stretched piston seal and piston, then cut it so there is about a 1/4 to 3/8 gap between the to ends of the wear ring, file the sharp edges off and then use a quick adjust gear clamp to compress the wear ring and piston seal, careful not to pinch the seal in the gap. sometimes the first compression is not enough so cut another small piece of wear ring out, file and compress it on the seal again. Depending on the type and style of piston leave them on until the tube pushes it off. ie if the piston has only a piston seal and wear ring, with the piston seal closest to the rod. lube and insert piston in to the tube up until the piston seal and then drive the rod in which will push the gear clamp and wear ring off. I have used this technique on all types of cylinders and have found it to be the most efficient method I have came across