junkhound
Senior Member
- Location
- Renton, WA
- Occupation
- EE, power electronics specialty
Finally got around to cutting the bottom off a failed copeland scroll 4T compressor to look at the bottom bearing. Bearing itself good, -- had previously looked at the top bearing and found 16 mil shaft side to side play on end of 1.5" shaft but only 1.5 mil sleeve bearing clearance.
Mystery solved - DEFECTIVE copeland assembly, screws attaching lower bearing to steel mounting plate shook out over time, allowing rotor to contact stator.
NO problems with oil or SSH or anything else in the refrigeration loop, defective factory assembly of the compressor -- e.g. they left the loctite off these screws?
There is a 3 tab bracket that is the lower bearing attachment, 3 ea specialty screws agttach the bearing to a steel plate - all 3 of those screws had shaken out over the last 15 years, allowing extra rotor play. I measured the journals and the shafts, < 3 mil clearance, typical of sleeve bearings, so no bearing wear to speak of. The lower bearing becomeing loos from the case allowed the play to let the rotor grind to a halt against the stator.
-- hope the photos show up... They should be self explanatory, the steel mounting plate shows where the loose bearing oscillated till all 3 screw shook out, then there was enough play to lock the rotor as seen by the scuffed rotor.