There are a couple of service literature items available for download here:

Here's a quick peek at the earlier Whirlpool belts and pulleys in operation on my 1956 Whirlpool Imperial dryer.

I didn't get a got shot of it, but there was a really different belt switch assembly to ensure the drum was turning before power got sent to the heaters.  When the dryer stops, there is a distinct chatter that can be heard as the switch spins down - it's also typical of the Whirlpool dryers of this vintage.