In order to form a tensioning apparatus for a switch-on energy store of a circuit breaker, in which apparatus a tensioning shaft, which can rotate by means of a drive wheel, for tensioning the switch-on energy store is fixedly connected in each case to a cam and to a cam disc, which apparatus has a tripping stop, in which apparatus the drive wheel is coupled to the tensioning shaft via a clutch, and which apparatus has a simple and at the same time cost-effective design, the invention proposes that the clutch is a ratchet arrangement.