Coupling Degeneration [multiple pumps affected]

That looks like a flexible coupling to me. Do you have any details of the coupling.

It s implying that there is mis alignment between pump and motor. Were the pumps properly aligned after installation?

In my early days I knew nothing about alignment, installed a 15kW pump, set it all up and during commissioning we noticed some odd noises and a bad smell.

Opened up the coupling guard and the flexible coupling a bit like that one had plastic oozing out of the holes and was rather hot....

Lesson learnt - get the installer to align the pumps and motors AFTER you've fixed them on the plinth and added pipe connections.

In service the pipes if they expand or contract can flex the pump and force the couplings be errr flexible more than they should.

How old are they?
What are the installation and maintenance instructions for these couplings? They do look a bit chewed up.
Do they warm up in use or make a strange noise?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

> Do you have any details of the coupling.

I'd say it's a pin and bush style coupling (which allows relative axial movement of the two shafts without transmitting any thrust). Op is welcome to chime in.

We can guess likely contributors to degradation. Misalignment mentioned is a good one. Perhaps chemical influences (is that powdery stuff from abrasion of the washer or something else). Looseness of washer on the bolt or excess looseness of washer in the hole might play a role/ although the latter is probably established by the parts.

But even in ideal conditions, it doesn't look like a part that is expected to last forever (especially if you're seeing the same thing on multiple machines). I'd think about asking the OEM if there is a recommended replacement interval. If you come up empty on that, ask yourself whether you think you can reliably detect this type of degradation based on vibration or other symptoms (maybe bits of washer accumulating below the coupling guard) before it causes an unacceptable problem. If (as I suspect) the answer is no (we can't reliably detect it in time), then I'd think about setting up time based replacement at some interval less than the run time that those washers have since they were installed.

They look very loose?

Need to see the detail.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

If the coupling is failing prematurely I would suspect overload or misalignment. Your foundation, from the top view, does not appear rigid enough to maintain alignment of the coupling.


I also saw zero evidence of an alignment being performed. There are no shims under the motor and there is no hardware for jacking screws.

> There are no shims under the motor and there is no hardware for jacking screws.

Good catch.

For all couplings the better the alignment the longer the life.
The long used millwright alignment method using dial indicators is explained here
rim and face alignment - Jack Of All Trades Training
Use of Laser alignment tools provides the best results, and can create a report for record. Alignment cold does not always produce acceptable alignment under operating conditions. Better alignment will result in longer service life.

The particular coupling OP shows (web search "Pin and bush couplings") is one I used to repair. Repair is easy as you can purchase the bushings or make them.
Bushings dimensions are NOT standardized between brands, try to find the MFGR's stanp under the paint, it will help find parts.