Valjoux Cal. 77 ECO is a column wheel chronograph movement. Unusually for Valjoux, it has seven columns in the wheel used to control the chronograph function and also uses Heuer’s oscillating pinion engagement design. It is a two-pusher movement with a 30 minute chronograph register. Cal. 77 was produced from 1946 through about 1950. The Valjoux 92 was a descendent of Cal. 77.
Valjoux designed the unusual Cal. 77 with two goals: It implemented the oscillating pinion for use by Heuer, and it replaced many complex milled components with springs to reduce cost.