The first Frigidaire Mechanism, the Unimatic was a single speed only.  In 1959 the Multimatic Mechanism was introduced.  This employed a two speed reversing motor.  Slow/fast agitation was achieved in one direction and the spin in the other with the use of a direct drive clutch in the mechanism.  Pumping from the outer tub was capable in either direction.

In 1965 the first Rollermatic Mechanism was introduced.   This was a true direct drive mechanism using urethane and aluminum rollers to achieve the same result, spin speed was back up again in this mechanism to 1010 in Rapidry models.  There were many configurations of this model, a single speed, two speed, infinite control, and four speed.  The multiple speeds were achieved with the use of engaging different rollers with solenoids.  For example my Rapidry begins its speed on slow spin, slow motor speed, next it ramps up to a middle speed by engaging the solenoid for the high speed spin roller on the secondary clutch roller, next the motor speed is increased to fast in order to achieve the Rapidry Spin.  The infinite speed use some sort of "static clutch" if I remember correctly.

1970 introduced the 1-18 Models, still employing the rollermatic mechanism but it was a belt driven version and also designed to handle the larger capacities of the 1-18.  Most used two speed motors, a few rare machines were three speed.  No solenoids were used on this mechanism, only the rollers and changes of motor speeds.  It was a simple, easier serviced, more reliable mechanism

A good dig through the archives here will turn up more information, along with pictures.  Some posts will be mine, others from fellow members.

Pictured below is the mechanism on my 67 Rapidry and a 1-18 mechanism.

Thanks for the great explanation Joe, my favorites by far are the Rapid-dry 1010 rollermatics, but I agree that the best and most reliable AWs Frigidaire ever built were the 1-18s, they were much easier to work on and longer lived.

good point, I never thought that thru till  you mentioned it, the MM pump was designed to pump out in either direction and that was carried over to the new rollermatics until 1970. The 1-18 pumps can only pump in one direction because of the perf-tub.

Will pump water in either motor direction, the early 1-18s were available with suds-savers that utilized this function.

I think these may have only been around in the first series of 1-18s this feature certainly did not last long which is a shame because they finnilly had a much simpler plumbing system that did not need a 2nd water pump. Solid tub washers were always complanted with Suds-Savers.

1-18 Quality While the first series of these great washers did have a few problems after FD worked a few bugs out these washers were far more durable than the solid tub rollermatics.

I have seen maybe one broken belt in a 1-18, no main seal failures, no water bellow failures, no roller failures in the later 1-18s. We still have customers that are using 1-18s and it has been more than 25 years since I walked into a house that was still using a ST RM.

NOW the 1-18 dryers are another matter even though these were simple good performing dryers very few of these lasted as long as the washers.

 ...it has been more than 25 years since I walked into a house that was still using a ST RM.

John, don't you have a set in your own house?! 

I'm wondering if the small capacity is also something that lead to the replacement of the solid tub washers.  The 1-18, once they fixed the early production problems were probably more reliable than the Rollermatics and I guess many were scrapped because of minor failures like timers that stop advancing.

Some techs that I know hated to repair the 1-18s (which they called the "American" machines here as none of them were made in Canada!) when they needed to fix a machine that leaked from the tub seal.

But the water bellows are certainly better in the 1-18 models than in the previous solid tub machines but their failure lead to a big mess on the floor while the same failure in a solid tub will lead to an empty inner tub and not a drop of water on the floor. 

The last suds saver model was a 1971 "S" model, the WCDRS which was made from 1970½ to 1971½), so they were among those early production troublesome models. I still wish I could find one of these. I have bought a 1971 WCDS (same model without the suds saver) but it turned out to be a newer machine from 1978-79 with a 1971 top.