AMT 3891-99 Pump Pedestal, 56J Threaded Shaft
The AMT 3891-99 is the genuine AMT pump pedestal for NEMA 56J frame motors, supplied with a 7/16-20 UNF-2A threaded shaft. A pedestal is the structural and mechanical bridge between a motor and a pump end: it houses its own bearings, carries its own shaft, and lets the pump be driven by a standard motor without the motor’s bearings having to take the pump’s loads.
That separation is the whole point of the design. In a close-coupled pump, every bit of radial load from the volute and axial thrust from the impeller goes through the motor’s bearings, and a seal failure puts liquid straight into the motor. A pedestal takes all of that on its own bearings and its own shaft, in its own housing, where a failure costs a pedestal rebuild rather than a motor. It also means the same pump end can be driven by whatever motor suits the installation.
The 7/16-20 UNF-2A thread on the shaft end is what the impeller lock nut threads onto, and the 56J frame designation identifies the motor face the pedestal bolts to — both need to match what you have. Motor frame sizes that look similar are not interchangeable, so check the frame stamped on your motor nameplate before ordering. If you are working out a replacement for an existing installation, send us the details and we will go through it with you.
Key Features
- Genuine AMT (Gorman-Rupp) pedestal — built to the original specification
- For NEMA 56J frame motors
- 7/16-20 UNF-2A threaded shaft for the impeller lock nut
- Carries the pump’s radial and axial loads on its own bearings, protecting the motor
- Keeps a seal failure out of the motor windings
Applications
- AMT pump installations driven by NEMA 56J frame motors
- Replacing a pedestal with worn bearings or a damaged shaft
- Building a pump end onto a standard motor
- Protecting the motor from pump loads and seal leakage
- Marine, dockside, dewatering and general water transfer service
Specifications
- Brand: AMT (Gorman-Rupp)
- Manufacturer Part Number: 3891-99
- Part Type: Pump pedestal
- Motor Frame: NEMA 56J
- Shaft Thread: 7/16-20 UNF-2A
- Condition: New
Not sure this is the right part? Send us a Picture of the pump plate on your pump and the CLR Marine team will confirm the correct pedestal before you order.
CLRMarine
