The present disclosure is directed to providing mobile excavators with a firm footing when working on rough terrain. The disclosed device (70) for locking a swinging axle of a mobile excavator and for operating a service brake (66) of the mobile excavator has an activation state and a deactivation state and is configured to both lock the at least one swinging axle and also operate the service brake (66) in the activation state if predetermined operating conditions of the mobile excavator are fulfilled, and to unlock the at least one swinging axle and to release the service brake in the deactivation state if the predetermined operating conditions are not fulfilled.