The cause of hot and sluggish pump operation was found to be a simple problem.
The Old Timer of Royal Oak, Mich., was a regular contributor to H&P years before we ever even heard of the internet. But most of his advice is just as ueful — and interesting — today.
So rather than leave his wisdom printed on pages archived in our storage room, I pulled out issues from the late 1980s and early 1990s and reproduce relevant entries in this blog. Here is my fourth entry, which was originally published in the August 1987 issue:
Maintenance tip: don’t forget square one
Even when an industry or company makes a concerted effort to standardize, it’s more than likely that a large manufacturing facility will wind up with a variety of production machines from many OEMs. All these machines will include components from even more manufacturers. Add a three-shift operation with a large maintenance staff, and you can see how difficult it is for any individual to become familiar with all the elements on any piece of equipment. Finally, throw in the natural tendency to assume that the person who installed the equipment knew what he was doing, and you have all the ingredients to turn a simple error into a major puzzle.
In our plant, a pressure-compensated pump from a reputable manufacturer ran hot from the day it was first started—eventually raising the reservoir temperature and tripping a safety switch. The machine involved also seemed sluggish.
Someone decided to rebuild the pump, but bearings, rings, vanes, plates, and such all checked out OK and the pump still ran hot. The next step was to replace it and when the new pump didn’t solve the problem and the shaft seal flew, we had to go back to square on.
With only four pump connections—inlet, outlet, gauge, and drain—what could be wrong? In fact, there wasn’t even a gauge in the gauge port. It had been plugged because we used downstream gauge ports with quick-connect couplings in our plant. Let’s take a look anyhow.
And there it was. The set-up man had interchanged the case drain and the gauge port. He plugged the case drain and the pump had been pushing about 3-gpm through the gauge port to tank whenever it ran. Because this port was part of the governor, it caused the pump to be sluggish on recovery. That one little line didn’t stop the system but it sure caused some headaches.
To try to avoid this type of situation on other machines, we began to make copies of all instruction and service sheets for each machine and send them in protective plastic folders to the departments where hydraulic equipment to located. We believe the time spent doing this saved many maintenance hours on the production floor later on.