Have an old 1947 D2 with a hydraulic blade. IThe cylinders were leaking at the front, so I took it all apart. The packing looked like graphite style packed in firts, they the outer looked more like hemp styl. Are there different types of packing used in these cylinders? Where can I get some larger diameter graphite packing? How tight do I pack it in?

The tube did not have any "O" rings on either end, just tight fit with what looked like an old gasket. Did they take anything special to seal the ends?

Thanks, Scott

There is a good chance you can get the packing from Cat. Then you will know you have the right size and type. There were two styles of cylinders, early and late and I am assuming you would have the early style. If you change the piston seals you should also get those from Cat as the after market junk does not have the right cross section and will soon blow out.
The cylinder ends seat against a brass seat in a groove in the end housing, do not damage these as to my knowledge replacements are not available and would have to be fabricated.

Don't think it's a Cat original. Doesn't look like the picture. I've looked on the web and find about a dozen types of packing, not really sure whicj to use.

Most generic hydraulic cylinders use a v-type (chevron) packing with end adapters. Your best bet would be to take the dismantled unit in to your local hydraulics supply house and have them fix you up with what you need. Also helps if you can identify the cylinder manufacturer.

Hi Old Magnet,
I'm working on an RD-4 with a Cat 4A blade. The hydraulic cylinders look the same as the diagram that you posted. Did the D-4 use the same cylinders or bigger ones?
Thanks.

Looks like same bore and some shared parts but longer stroke (early cylinders)

I am also in the process of rebuilding my cylinders. My Cat is a 1949 5U with a 2A blade. As I owned a machine shop for 25 years, the first thing I checked (after disassembly) was the outside diameter of the piston rod all along its length. What a surprise!! It was .020" less in the middle than the ends. I assumed that no matter what seals I replaced, it would not work properly. I went to my friendly Cat dealer and purchased all the seals and locks to rebuild the cylinders. The gland seal they supplied is incorrect, even though the gland is an original Cat part. I may have to bore out the gland to accept the seal supplied.

As Cat was rather expensive to remake the piston rod ($480 each), I found a local precision machine shop to make new rods. They are using 1045 steel shafting with .0005" of chrome plating.

This project has been more than I expected, but I feel it's important to do it properly.

Occasionally I hear of piston rods being produced from stainless steel (400 series I believe) and forgoing the plating process. Anybody have experience or comment on this process???

Old Magnet,
Responding to your inquiry about 400 series rods. I don't think stainless would be a good choice of material for a couple of reasons. Contrary to popular belief, stainless is not hard, but tough. One alloy which is very machinable is 416, with a machinability rating of 110% as compared to 1212 at 100%, however, it has poor weldibility. About the best hardening would be to about 45 on a Rockwell "C" scale. Chrome plating is probably over 65 on that scale. Also, it would be difficult to weld to the mild steel "eye". One other consideration is cost. Stainless is expensive!!! I recently priced 2" OD 1045 rod with .0005" chrome at about $25.00 per foot.