Unimac (Primus) Rattling Noise

[pulsator]

My beloved Unimac seems to have an issue… It has developed a rattling noise of some kind while coasting down from spin. I’ve had the top panel, toe panel, and rear panel off and cannot seem to find anything loose that could be making the noise.

There is a little bit of play in the main pulley on the drum (not wobble, just a touch of rotational play) that could be causing it, but there also seems to be an issue with the main bearings I fear as the center of the back of the drum gets pretty hot but the end of a cycle. (Hot enough that I don’t want to keep my hand on it but I can.)

Hoping someone here might be able to help me diagnose the issue as I’ve never worked on a commercial machine but I guess there’s no time like the present to start learning!

As for the pulley, I can understand play developing if there is excess friction in the bearings, but I don’t know how much play, if any, is acceptable. I also don’t know if it’s common for heavy duty bearings like these to heat up some amount during use.

According to the machine’s log, it has run just 285 cycles in its lifetime, so there is definitely something not right, it’s far too young to be having such issues.

Video of intermediate spin

 

[henene4]

Bearings do get quite hot even when running properly, especially at high speeds.
It's not uncommon for the back of the drum to feel almost body temp in machines over here, especially with very large drums and extra high spin speeds.
That's for example why Miele has a patent about their plastic tubs with metal bearing supports in them to disapate heat.

Play in the pully however does not sound right - though it's odd it's radially?
Usually, these are keyed in a way that any rotational force is transmitted through the fit of the 2 parts - the bolt in the back just keeps stuff from moving apart.



Again on another hand though, that sound sounds a lot like springs to me.
Some earlier Miele W1's had a similar kind of noise that was down to how the springs are mounted in the cabinet and the tub.
That's also why metal tub machines are kind of more common with such noise issues.

You could alway see what grease is on the springs (there usually is some) and see if you can source any and reapply.
Besides being messy and as long as dosen't get onto stuff like the belt or any rubber parts there really isn't to much grease at the spring-structure interface.