Actuator for a brake system of a rail vehicle - comprising a set value detection unit and a set value control device, - wherein the set value detection unit provides, at an output, a set value (Sset) or a set value (Sskid) adjusted under the influence of a reducing signal of an anti-skid protection control device for a decelerating force (Fv) to be controlled or a decelerating torque (Mv) to be controlled and transmits said set value to an input (El) of the set value control device, and - wherein the set value control device controls the set value (Sset; Sskid), transmitted by the set value detection unit, to a first output set value (ASvl), - comprising a fall-back unit, which provides a predefined second output set value, - comprising a set value/force conversion device, - comprising a switch-over device, which connects an output (A2.1) of the set value control device to an input of the set value/force conversion device in a first switching position, so that the first output set value is present at the input of the set value/force conversion device, and which connects an output (A2.2) of the fall-back unit to the input of the set value/force conversion device in a second switching position, so that the second output set value is present at the input of the set value/force conversion device, - wherein the set value/force conversion device converts the output set value of the two output set values present at the input into an actual value (Ip) of a force (Fp) for braking the rail vehicle, - comprising braking means (16, 17, 18), which convert the actual value (Ip) of the force (Fp) into an actual value (Iv) of the decelerating force to be controlled or of the decelerating torque (Mv) to be controlled, - comprising a sensor, which determines the actual value (Iv) of the decelerating force (Fv) to be controlled or of the decelerating torque (Mv) to be controlled and provides said actual value at an input of the set value control device, - wherein the set value control device sets the first output set value (ASvl) in such a way that the detected actual value (Iv) corresponds to the set value (Sset; Sskid) transmitted to the set value control unit by the set value detection unit, and - comprising a monitoring unit, which receives a fast braking set value (FB-set) or at least one correction factor (fK-load, fK-H/L, fK-GB) for calculating the fast braking set value (FB-set) from a fast braking set value determination device in the event of a fast braking operation, receives the actual value (Iv) from the sensor and outputs a switch-over signal to the switch-over device in the event of impermissible deviations of the actual value (Iv) from the fast braking set value (FB-set), which switch-over signal causes the switch-over device to switch over from the first switching position thereof to the second switching position thereof. - comprising a set value detection unit and a set value control device, - wherein the set value detection unit provides, at an output, a set value (Sset) or a set value (Sskid) adjusted under the influence of a reducing signal of an anti-skid protection control device for a decelerating force (Fv) to be controlled or a decelerating torque (Mv) to be controlled and transmits said set value to an input (El) of the set value control device, and - wherein the set value control device controls the set value (Sset; Sskid), transmitted by the set value detection unit, to a first output set value (ASvl), - comprising a fall-back unit, which provides a predefined second output set value, - comprising a set value/force conversion device, - comprising a switch-over device, which connects an output (A2.1) of the set value control device to an input of the set value/force conversion device in a first switching position, so that the first output set value is present at the input of the set value/force conversion device, and which connects an output (A2.2) of the fall-back unit to the input of the set value/force conversion device in a second switching position, so that the second output set value is present at the input of the set value/force conversion device, - wherein the set value/force conversion device converts the output set value of the two output set values present at the input into an actual value (Ip) of a force (Fp) for braking the rail vehicle, - comprising braking means (16, 17, 18), which convert the actual value (Ip) of the force (Fp) into an actual value (Iv) of the decelerating force to be controlled or of the decelerating torque (Mv) to be controlled, - comprising a sensor, which determines the actual value (Iv) of the decelerating force (Fv) to be controlled or of the decelerating torque (Mv) to be controlled and provides said actual value at an input of the set value control device, - wherein the set value control device sets the first output set value (ASvl) in such a way that the detected actual value (Iv) corresponds to the set value (Sset; Sskid) transmitted to the set value control unit by the set value detection unit, and - comprising a monitoring unit, which receives a fast braking set value (FB-set) or at least one correction factor (fK-load, fK-H/L, fK-GB) for calculating the fast braking set value (FB-set) from a fast braking set value determination device in the event of a fast braking operation, receives the actual value (Iv) from the sensor and outputs a switch-over signal to the switch-over device in the event of impermissible deviations of the actual value (Iv) from the fast braking set value (FB-set), which switch-over signal causes the switch-over device to switch over from the first switching position thereof to the second switching position thereof.