How to Change The Disc Assembly on A Double Disc Pump

When Wastecorp designed the Sludge Pro Double Disc Pump we set out with the goal to engineer the easiest to service sewage pump available to engineers and WWTP end users. One common request from the engineering community was that an operator or maintenance person would never have to crawl under a double disc pump with a casting hanging overhead and the potential for sewage to leak over the operator. When you think about – why would anyone design a pump like that? Our answer is that you would have to ask the competitor because Wastecorp would not.

double disc pump service
Servicing a double disc pump

The video below shows how to change the trunnion on a Sludge Pro double disc pump. As you can see most of the maintenance is done with the operator standing up and most components visible to the operator.

Safety First

Removing the guard on a double disc pump
Removing the guard for servicing on a double disc pump

Changing the disc assembly on a Sludge Pro double disc pump is a simple process which can usually be done within 30 minutes-45 minutes. First you want to make sure that power to the pump is disconnected. You also want to make sure that all of the valves to the pump are closed so that fluid cannot flow to the pump while maintenance is performed. You also want to ensure that you are wearing a hard hat, steel toe boots, hand protection, eye protection and adhering to all procedures outlined in your operators manual when performing maintenance on your double disc pump.

Remove Guards
First remove safety guards from the upper housing of the pump. Depending on your pump model, it is either a one piece fully enclosed access hatch or a screen that surrounds the upper housing.

Coupling Removal
Next, remove the yellow coupling guard with a half inch wrench that sits close to the gear box with a 9/16” wrench. Now, remove the coupling retaining cap which is connected to the coupling flange. At this point you can remove the flange bolts on the other side of the coupling. It is a good idea to have one other person assist with this step. You can now remove the black rubber dampeners from the coupling. This allows the flange to easily slide out during the elevation of the upper housing.

Housing Bolt Removal
Now remove the eight housing bolts that connect the pedestal to the pump. You should be placing a removable guide rod in at least one of the housing positions to stabilize the motion of the pedestal rising.

Double Disc Pump Hydraulic Jack
You can now begin to raise the pump pedestal by locating the hydraulic jack mounted on the side of the pump. In smooth strokes pump the jack and watch the upper housing rise. Make sure you have put at least one temporary guide rod in place of a housing bolt to ensure smooth and stable rising of the upper housing.

There should now be more than eight inches of space between the pedestal and pump body to remove the trunnion.

Trunnion Removal- Disc Assembly Removal

Using a ratchet begin removing the trunnion. Use a smooth motion to remove the trunnion. Once you feel that the trunnion is almost disconnected, manually twist the trunnion off and remove.

Place the trunnion and disc assembly on a flat surface and remove the retention ring bolts with a socket wrench. Remove the retention ring and the old trunnion. Reinstall the new trunnion and put the retention ring back into place.

You are now ready to reconnect the disc assembly. Use the rachet to connect the trunnion to the connecting rod. Use the hydraulic jack to slowly lower the upper housing into place.

Now you can reconnect the pedestal to the pump body with 8 gland bolts. Be sure that you remove the guide rods before connecting the bolts.

Reconnect the coupling retaining cap and the coupling flange. Ensure that you torque socket bolts using a torque wrench to one hundred and sixty foot pounds.

Your Sludge Pro double disc pump is now ready to fight sludge at your facility again. This is one of the easiest double disc pumps to service on the planet. For helpful maintenance tips or getting a Sludge Pro at your facility speak to a double disc pump expert from Wastecorp at 1-888-829-2783 or visit

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