Spool repair

dstankus · Jul 10, 2018

I have an old hydraulic valve that leaks and I have begun to investigate the issue. After taking the spool out of the valve body I see that the top sealing surface is pitted and imperfect. Does anyone know of a way to do a cheap repair to these or is a replacement part the only option. It currently has a noticeable leak that I would like to eliminate or at least reduce.

I have thought about using silver solder on the pitted surface and then polishing/machining back to the right dimensions but am concerned about the heat warping the spool.

I also thought about using JB weld on the pitted area, then polishing the surface back to the right dims but to me this sounds fairly unlikely to work.

The valve is an old Vickers CM11Z01-R30D DL21059 and I have attached a picture of the spool as well. Any suggestions would be appreciated. Currently I understand that this series of Vickers valve is obsolete.

bigdeano · Jul 10, 2018

I would try lead-tin solder. It will probably warp if you get it red hot for silver solder.

I bought a CM11 valve many years ago at a surplus place that turned out to be a motor spool valve. I soft soldered some half-circle pieces on it and machined them to convert it to a tandem center for a cylinder. Has been working fine for almost 40 years.

BeezFun · Jul 10, 2018

dstankus said:
After taking the spool out of the valve body I see that the top sealing surface is pitted and imperfect.

Can't say for sure, but that looks like the only pitted area is on the surface where the oring provides a low pressure seal. You could confirm that by measuring where the oring groove is in the valve body and then seeing if the start of that pitted area lines up with that position when the valve handle is in the extreme position. If it's really the oring surface, I think you have good chance of making a repair that seals. But if any part of that corrosion is on the part of the spool that seals high pressure using metal against metal, I think the required tolerances are too tight for anything you try to be successful.

Dave M7040 · Jul 11, 2018

Spool valves are manufactured to tolerances so tight that few people even have the accurate tools needed to measure it.

0.0002 Check the number of zero's

This tiny clearance is why the spool valves do not have lots of internal seals. With the tiny clearance, seals are not needed.

Dave M7040

dstankus · Jul 12, 2018

We wound up adding solder to the spool and then machining it back down to where it originally was manufactured. The worn spool was between 0.005 and 0.007 short of where it was after manufacturing before we applied the 50/50 solder. I have attached a before and after picture of the repair. It still leaks a little, but I bet after I get a new seal and backup ring the leak should totally stop for a while at least. I wonder how long it will last. Thanks for the help.

npalen · Jul 12, 2018

Looks like it needs to be polished smooth or the ridges will take out the seal.
Also, if the machined surfaced was done on a lathe with power feed there will be a potential for spiral leakage under the seal.