Imagine for a second that it’s Friday afternoon and you’re headed towards a nice long weekend with Saturday off and an operator informs you your Waukesha PD pump has seized up. Or your flowmeter tells you you’re getting less flow than you’re expecting. Now what? Worried that your pump is going to ruin your weekend? Not so fast. At Triplex, not only do we sell hundreds of new Waukesha Universal Series pumps every year, we also help our customers service and support their installed pumps. Being hands on with so many Waukesha and Ampco PD pumps, we’ve developed a quick punch list for you to run through to evaluate and triage your PD pump and get back up and running in no time! Let us walk you through it in today’s post.
Check the Serial Numbers
First things first- understand what you’re dealing with. While a pump may look fine at first glance, we often find end users who are mixing and matching pump covers, bodies, rotors, and gearcases. Generally speaking, this is a no-no. A Waukesha Universal pump gear case is shimmed to match a specific cover and body and by using a body or rotors from another pump, we can greatly impact performance. When the shafts are not shimmed for a specific body, we can create excessive clearances, which leads to pump inefficiency and slip. On the flip side, if the clearances are too tight, you risk the rotors contacting the body or the cover, which is also not good.
Remember that the pump cover, body, and gearcase all have a serial number. Make a quick note of each and verify that they match. If they don’t consult your local SPXFlow Platinum distributor to retrieve the serial card for each component, review, and re-shim if necessary.
Measure the Rotor Clearances
Ok, well what about the rotors? What about the serial number on those? There is no serial number on the rotors, but that doesn’t mean we don’t want to take a closer look at them. First, if when we reviewed the pump serial card we saw that the pump was an R1, we want to make sure we’re using an oversized R1 rotor.
The easiest way to figure out if we’re using the right rotor and body combination as well as eliminate the rotors as a source of inefficiency is to measure the clearances. There are three clearances we’re going to want to check- the back face clearance (back of the rotor to the pump body), the front face clearance, and the rotor to body clearance. If our back face clearance isn’t in tolerance, that’s a sign rotor wear that can lead to volumetric inefficiency. If the rotor to body clearance is uneven, that can be a sign that we bent a shaft. Excessive clearances between the body and rotor can also be a sign of rotor wear. Finally, measure the front face clearance. We want to be sure all clearances are in tolerance before putting the pump back into operation.
Check Seals
Now that we’ve checked the rotor clearances, we’ll want to pop them out and pull the pump body on a U1 or U2 and inspect the product seals (we can leave the body in place to do this with a U3). The product seals are what keep product in the pump and off the floor. We’ll want to inspect the seal faces and make sure they’re free of chips and cracks, as well as o rings and make sure they aren’t worn. While doing this, it’s a good idea to change out our soft parts and inspect the body and shafts for any wear. A good tip to make sure the seal faces are still good is to wet both the stationary and rotary seal faces and see if they stick together. Assuming they do, you can continue to use them. If they don’t, that’s likely where your leak is coming from. On Universal 1 pumps, we should also double check that the shaft o-rings are in the right position- in the front o-ring groove on an o-ring seal and in the rear o-ring groove on a mechanical seal.
Check the Bearings & Gears
Now that the body is off and we’ve looked at the seals, we’ll want to check our bearings and gears- the most common place we find pump failure. The telltale sign of bearing failure is a seized shaft or noisy operation. We check for this by giving each pump shaft a firm handshake. If we see movement in any direction, we know the bearings are failing and need to be replaced. And if we can turn one shaft while holding the other shaft in position, we know we should inspect the pump gearing further. Find any of these issues and you’ll know it’s time to rebuild the gearcase.
Check the Oil Level
The final item on our punch list is to check the gearcase oil level. You wouldn’t believe the number of pumps we see that are bone dry- not a drop of oil. Sometimes they’re even still running- with the gearcase packed full of grease (you’ll know it when you smell it). To check the oil level, either look at the sight glass on the gear case or, easier yet, remove the oil drain plug and see if anything comes out. If oil comes out, you know you’re good. If nothing comes out, add oil until it does. As easy as that.
So the next time you’re headed into the weekend only to be made aware of a pump issue, start by checking the serial numbers. Next, measure the pump clearances before removing the rotors and body and inspect the pump seals. While you have the pump apart, inspect the gears and bearings and make sure there is oil in the gearcase. If everything checks out or there is a simple fix, correct it, reassemble, and check that the shaft turns. Assuming it does, you’re good to go. Still stuck? Don’t worry- just contact a Triplex Sales Engineer today and we’ll get you up and running in no time!
