A shaft mounted rotor brake (7) with at least one braking force absorption element non-rotatable connected to said shaft (1). A stationary brake actuator (8, 24) is mounted to a rotor gear box housing (4). Said stationary brake actuator (8, 24) actuates a braking force transmission element (17, 23) that is functionally coupled to the at least one braking force absorption element (2) so as to exert a braking effect. At least one rotor brake deactivation device (6, 9, 25) is provided. The at least one braking force absorption element comprises lamellas (2) interacting with stationary lamellas (3), said lamellas (2) and stationary lamellas (3) being arranged inside of the rotor gear box housing (4) with oil inside.