Re Rollator...
After Norge about went under due to the 1947 disaster ,when they tried using their so2 Rollator with Freon, resulting in so many of then going bad, they switched sometime in the early 50s to a more mainstream compressor, Im not sure but I believe they used a Copeland, they put a big gold heart on it and called it the Heart of gold compressor!LOL, If you look in the back of the 50s and 60s Norges, you will see the gold decal plastered on the compressor, after they dropped the Rollator, I think Frigidaire and Seeger"Coldspot" had the rotary market to themselves, GE Kelvinator and Westinghouse used more conventional piston compressor,but a Rollator or a Meter Miser each has its own distinctive sound, The Seeger built Coldspots are MUCH Quieter than the other rotaries...almost silent.