An actuating apparatus for actuating a shifting mechanism in a transmission to shift a gear wheel on a hollow shaft with an actuator module that is at least partially positioned within the hollow shaft and which comprises an actuator which can be connected with a coupling element of the shift mechanism which radially, inwardly extends into the inner diameter of the hollow shaft. The enclosure of the actuator module has at least an axially extending assembly passageway which guides the coupling element, during axial insertion of the actuator module into the hollow shaft. A method for the assembly and disassembly of an actuator module, with at least one actuator of an actuating apparatus for inside actuation of a shift mechanism on the hollow shaft. The actuator module is axially inserted into the hollow shaft and rotated via an assembly guide.