At first, cast lead with steel wires; later, solid steel.
Center Pinion Construction Cast lead with steel wires:
Traditional Westclox-style pinion with cast lead alloy body and 8 steel pinion wires. Latest example seen: 1920-3-1. Used with mainwheel of 60 teeth 27 mm diameter.
Center Pinion Construction Solid steel:
Solid steel pinion with 9 leaves. Earliest example seen: 1920-4-24. Used with mainwheel of 59 teeth 26.6 mm diameter.
