my big swivel casters have frozen up and don't want to swivel anymore

[metalmagpie]

I have some large casters on the gantry crane that is normally in my driveway, now torn down for maintenance. These casters are quite substantial. Each caster is rated for 3500 pounds, and weighs about 62 pounds. They are heavily made, with most parts of the body and plate being 1/2" steel. It's a long story,. but I have two pairs. One has green wheels which were put into service about 5 years later than the others which have blue wheels. They all came from the old Boeing Surplus. Here is the manufacturer's link:

https://www.rwmcasters.com/products/...series-casters

I have all 4 casters off and upside down on a wheeled platform (which isn't too happy about the weight). The blue casters swivel with the slightest touch. The green ones were totally locked but I soaked them in PB Blaster and worked them and now they will begrudgingly turn but far from easily.

My theory is that the green ones have some kind of grease that has caked up. It doesn't feel like rust, not to mention that the other casters have been in exactly the same weather for a long time.

How would you suggest I go about trying to free these up?

metalmagpie

[Joel]

If I understand correctly, I would probably:
Blow out what I could around the full circumference, with a strong air stream.
Soak them overnight in my gunk tank (or bucket w/diesel, etc), working them back and forth periodically (on each step), then blow them out well.
Hose aggressively with cheap carb cleaner w/the straw jammed in, then blow out again (then rinse, lather, repeat as req). Hopefully, they feel pretty clean by now.
As for lube - probably would use my spray lithium copiously. Chain lube might be ok, then wipe off all the excess.

[PStechPaul]

Could the balls or races have gotten distorted? That would cause them to make a rumbling noise as they swivel. That would be unusual, as such parts should be hardened, but could be a bad lot or fakes.

[old mart]

The bigger ones are often rebuildable, with luck you will be able to replace the balls.

[Arcane]

The bigger ones are often rebuildable, with luck you will be able to replace the balls.

I can even replace the balls in the little castors on my floor jack.