Potato Pulley
The Potato Pulley makes the rpm vary a bit during the wash and rinse cycles; ie non spin/extract modes. A spec sheet says 57 +/- 2 rpm one place; and 57 to 62 in another place.
The pulley is called a "multi speed pulley" in a repair manual; and "Pulley eccentric" in another, or low speed sheave too.
On this board "potato pulley" is used a lot as the term, which is decent since the pulley is not an true oval.
In some parts houses that sell washer belts; the term "egg pulley" is used too.
The having the rpm vary helps with better washing, clothes get unstuck better.
Having the potato pulley (orange in diagram ) not round means the intermediate idler pulley ( yellow in diagram) is spring loaded, thus there really are little issues. The yellow idler bobs up and down,
Re "I would think it would make for a very rough ride for the drive belt and mechanism. "
There are felt pieces between the two curved springs ( items 1 and 3 in diagram) , these can squeak if old or dry.
The weak area is the overrunning SGS clutch item 18. This is like a slinky, it overruns in spin mode when the spin pulley (in blue) is driven directly by the motor split pulley ( #45 to #48 in red ). This spring has to be lubed with a good boundary layer grease, ie one made for sliding. The giant solenoid (#52) is live in spin mode, it pushes finger (#41)and the split pulley (red) drives belt (#29)
In wash mode the SGS spring grabs the hub (#17) which is keyed to the shaft (#8)
The noisy video here is because the shaft is worn down after 30 years (in the pink area in the diagram) . The washer is in spin mode, this is crummy video I shot with a cell phone in a hokey poor mode. At the end one can see the driven Blue pulley, the back is off the washer. I have a brand new shaft (#8) that is going to be replaced in the next month.
