Buchli drive

Buchli-Toggle drive with inner frame

The Buchli drive is a transmission system used in electric locomotives. It was named after its inventor, Swiss engineer Jakob Buchli. The drive is a fully spring-loaded drive, in which each floating axle has an individual motor, that is placed in the spring mounted locomotive frame. The weight of the driving motors is completely disconnected from the driving wheels, which are exposed to movement of the rails.

First used in electric locomotives from the 1920s, the Buchli drive made possible the construction of faster and more powerful locomotives that required larger and heavier traction motors. The system minimises the impact on rail tracks due to the reduction in the overall unsprung weight. Although the drive was very successful though the 1930s, it is little used in modern locomotives, having been replaced with smaller, simpler drives that exhibit less imbalance and allow higher speeds.