I was studying the belt shifting yesterday and like it better than that of the Rockford at Tuckahoe, which is over half a century more "modern". There are three pulleys on the input drive shaft of the planer. The center, wider pulley is "fast" (fixed to the shaft) and the ones on either side of it are "free" (rotate freely on bearings). The belt shifter uses a drum cam to shift the belts in a timed sequence that (I assume) was carefully thought out to minimize belt squeal by only putting one belt on the center pulley at a time. At any given time one belt or the other has its turn driving the center pulley, while the other idles on one of the free pulleys. The nice thing about this is that the belt on the drive pulley cannot fall off the edge and, although the idling belt is near an edge, it is not as critical so long as the driving belt is in place. I never dumped a belt on the Rockford, but it did not appear that it would be impossible.
For those who have not had the experience of watching a typical planer in action, of the two belts, one is installed in the normal manner, while the other is crossed in a figure 8 shape, reversing the direct of the output rotation. What might seem to be a strange way to dynamically reverse motion actually works quite well. A few "niceties" are that involved are that the crossed belt has a better "wrap" (longer contact) on its pulley and is less likely to slip at a given tension and that the upper pulleys can be different sizes, which gives the desirable "quick return".
Archie
P.S.: (OPTIONAL, but read to the end) I just got a message from a Craig's list potential buyer offering me the full $2K in the form of a certified bank check. English skills are lacking and I took the time to do an internet search on "bank check scam". I will leave the details to the reader, but I will not be replying.
Some other "tip-offs":
o I got an initial message within minutes of posting my listing, asking if it was still available. A human can read the time of posting at the top of the listing, but a robot does not bother.
o Craig's list username of "Alice precious". An hour later got an identical query from Alice's cousin: "John afred" with identical wording.
o Alice's second query, offered to mail the bank check mentioned assuming that the item was in "good condition, with no faults". I thought I was clear in the listing that this machine needed some TLC.
o Also there was no interest in loading or shipping method. Maybe typical for many Craigslist items, but we all know that this sort of detail is critical for handling machine tool sales.
Again, I will not be accepting this offer.
FINALLY, to quote one of the results of the above scam search: "Never, ever, accept a cashiers check from someone on Craigslist!"