Finish Thompson 105878-4 Drive Magnet Assembly, 8 Pole, 143 and 145TC Frame
The 105878-4 is the outer drive magnet assembly fitted to Finish Thompson DB11 and DB15 sealless magnetic drive centrifugal pumps that are close coupled to a NEMA 143TC or 145TC motor, with an eight pole magnet ring. It is the component that turns motor torque into pump torque without any physical connection into the liquid end. The magnets on this carrier lock onto the matching magnets in the impeller through the containment barrier, so the wetted chamber has no shaft penetration and therefore no seal that can weep aggressive chemicals into the workspace.
Replace this assembly when the pump has decoupled and lost performance, when the carrier shows cracks or lifted magnets, or when the bore has been scored by contact with the barrier. Decoupling normally traces back to a closed discharge valve, a viscosity or specific gravity above what the coupling was sized for, or a blocked suction, and the heat it produces can leave the magnets permanently weakened even though nothing looks broken from the outside. The eight pole 143 and 145TC version is specific: a 56C frame part will not bolt up and a six pole ring will not match the impeller magnet, so check the motor nameplate frame and the pump build before ordering.
Key Features
- Eight pole drive magnet assembly for NEMA 143TC and 145TC motor frames
- Includes the snap ring and stainless set screws for shaft mounting
- Transmits torque magnetically with no shaft seal and no leak path
- Neodymium magnet construction matched to the DB11 and DB15 impeller magnet
- Factory specification replacement that restores the original coupling rating
Applications
- Finish Thompson DB11 and DB15 sealless magnetic drive centrifugal pumps
- Transfer and recirculation of acids, caustics and aggressive solvents
- Surface finishing, pickling and chemical process skids
- Water treatment, scrubber and filtration recirculation loops
- Planned overhaul or repair after a decoupling event
Specifications
- Brand: Finish Thompson
- Manufacturer Part Number: 105878-4
- Part Type: Drive Magnet Assembly with Snap Ring
- Pole Count: Eight pole
- Motor Frame: NEMA 143TC and 145TC
- Included Hardware: Snap ring and stainless steel set screws
- Fits: Finish Thompson DB11 and DB15 series pumps
- Quantity Per Pump: 1
- Condition: New
Frequently Asked Questions
Q: How do I confirm which motor frame my pump uses?
The frame size is stamped on the motor nameplate, and a 143TC or 145TC motor carries a larger shaft and bolt circle than a 56C, which is the quickest visual check.
Q: Is there a break in period after fitting a new drive magnet?
No. Once the set screws are torqued and the snap ring is seated the coupling is at full strength immediately, though the pump should be started against a slightly open valve.
Q: Can this assembly run in an explosion risk area?
The magnet ring itself is one part of a larger specification, and pumps intended for classified areas are built with specific adapter and clamp ring options, so the pump build sheet decides that.
Q: What causes a new assembly to fail early?
Almost always a set screw that was not seated on the shaft flat, or a barrier that was already cracked and left in service, which lets the two magnet sets touch.
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 drive magnet assembly before you order.
CLRMarine
