What do the HOLES in the valve spools do? How do you repair?

Good question. Some valve spools have holes in the spool. Such as this hydreco valve off a drill rig.

There are a few different uses for holes in the spools such as:

1. Different valving in the spool itself
2. Anti-cavitation valving
3. Checks or reliefs

Holes are masked off so chrome doesn't get inside.  After chrome, the edges are cleaned to make sure flaking doesn't occur.  The spool is then ground to OEM tolerances 0.0005" or better.

Comments

[komatsu]

nice shot guys, good job