1970’s “The Friendly One” with Tokheim Speedisc Transmission

This is a bike I received in a donation. I”m curious to know anything about the Tokheim “transmission” setup and an approximate year? Thanks in advance.
Entry Submitted by Mark Brownlee

UPDATE: Info found on oldroads.com…. “The Tokheim was a five speed, expanding sprocket. In was introduced in 1974 and lasted until about 1980.”