After seeing yet another client rebuild a gear pump and then send it to scrap, I had to make a separate post on the subject.
While most of the gear pumps out there are throwaways that you simply replace when they wear out, some models (often on the larger side) are repairable - meaning you can get all the necessary parts, and with a good supplier, an overhaul of such a pump is economically viable. I am talking of course about the likes of Commercial Intertech and their countless clones.
In this post, I want to tell you about one catastrophic mistake, which "intrepid hydraulic equipment owners" are very likely to make when they venture to overhaul such pumps on their own. I've it seen more than once. Or twice. Or three times. Or... Well, you get the picture, right?
And I am not talking about an assembly mistake. Like the incorrect bushing position, pressure plates mounted the other way, or under-tightened bolts (which, by the way, is a huge deal for the Commercial units) - all this happens, of course, but these all are obvious and honest mistakes. No, I am talking about a mistake that destroys pumps when they are assembled one hundred percent correctly.
And the mistake is - the omission of the running-in procedure!
It may be natural to believe that a freshly rebuilt gear pump can be immediately put back into service, but, my dear daring friends, it can't. It needs these gears to gently and gradually carve into the body before it can take on the full system pressure.
So, if you just rebuilt such a pump yourself, (or you got it from a shop that doesn't run the pumps in, something that is absolutely possible), do the following:
Once again: If you hit a not run-in body with an instant full system pressure, you are very likely to break your pump! Please, don't do it, the pump has done you no harm.
Other gear-unit-related issues you may find interesting: