Robbins & Myers 320-1612-000 Pinned Nitrile Flexible Joint for Moyno 331 to 344
Part number 320-1612-000 is the genuine Moyno flexible joint built in carbon steel with NBR nitrile boot for the Moyno 500 Models 331, 332, 333 and 344 built with a pinned rotor. It is a small component carrying the entire output torque of the pump through a constantly flexing connection, which is why it is treated as a scheduled wear item rather than a fit and forget part.
Joints wear because they never stop articulating. Every revolution flexes the boot and works the internal bearing surfaces, and abrasive liquid that finds its way past a split boot accelerates the process sharply. The early sign is a knock or clatter at the pump end that changes with speed, and the late sign is a joint that lets go completely and leaves the rotor turning freely inside the stator with no output at all. Inspect the boot for splits and the joint for free play whenever the wet end is opened. Pinned builds also use two shaft pins at the joint, and the 316 stainless version of this joint is supplied as 320-4415-000.
Key Features
- Genuine Robbins & Myers Moyno replacement flexible joint
- carbon steel with NBR nitrile boot construction
- Sized for the Moyno 500 Models 331, 332, 333 and 344 built with a pinned rotor drive train
- Transmits full pump torque while absorbing the eccentric rotor motion
- Removes the play that causes knocking and uneven stator wear
- Direct replacement, no modification required
Applications
- Moyno 500 Models 331, 332, 333 and 344 built with a pinned rotor progressing cavity pumps
- Replacing a joint with a split boot or visible free play
- Curing a knock or clatter at the pump end of the drive
- Routine renewal during a stator and rotor rebuild
- Restoring drive to a pump that turns but produces no flow
- Industrial, marine and dockside pumping installations
Specifications
- Brand: Robbins & Myers
- Manufacturer: Robbins & Myers (Moyno)
- Manufacturer Part Number: 320-1612-000
- Part Type: Flexible joint, rotor to drive shaft
- Material: carbon steel with NBR nitrile boot
- Quantity Used: One per pump
- Fits: Moyno 500 Models 331, 332, 333 and 344 built with a pinned rotor
- Condition: New
Frequently Asked Questions
Q: Can a joint be rebuilt rather than replaced?
Pins and boots are sometimes available separately, but once the working surfaces inside the joint are worn the geometry cannot be restored, and a rebuilt joint that still has play will keep wearing the stator unevenly.
Q: Why does a split boot matter if the joint still drives?
Because the boot is what keeps lubricant in and the pumped liquid out. Once it splits, grit reaches the working surfaces and the joint moves from gradual wear to rapid failure, usually within a small fraction of its normal life.
Q: Should the joint be renewed every time the stator is changed?
On abrasive or heavily loaded duties it is good practice, since the labor is already paid for and the joint is only reachable with the wet end open. On clean light duty a careful inspection for play and boot condition is usually enough.
Q: What makes the carbon steel and stainless versions different?
Material choice follows the liquid and the rest of the pump build rather than performance. A stainless joint suits corrosive and washdown service where a carbon steel one would rust, and the two carry separate part numbers for that reason.
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 flexible joint before you order.
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