Using multibody dynamics, we investigated the behavior of a high-speed mechanism for operating a high-voltage gas circuit breaker (GCB). The circuit is opened or closed by using mechanical energy stored in compressed springs. The spring operating mechanism must be small and light. We used an analytical method to reduce the time for developing such a mechanism. The dynamic characteristics of a spring operated GCB can be modeled, so that the dynamic behavior of the entire GCB can be investigated. Investigation of the behaviors of the ratchet gear in a spring operated mechanism showed that the ratcher gear jumps after the interrupter contact closes. Using this analysis model and selecting an appropriate design will make it possible to improve the reliability of the ratchet gear before making a prototype GCB.