Multi-stage actuating system for a braking device of an industrial truck, comprising: - a housing which on one side comprises a through-opening for a piston and which is internally divided into a plurality of chambers (14a, 14b) by at least one intermediate wall which is perforated in portions; - a multi-part piston, wherein each of the piston parts (16a, 16b) is substantially accommodated in one of the chambers (14a, 14b) in the housing and only projects only in portions through the relevant opening in an intermediate wall delimiting the chamber (14a, 14b) or through the through-opening and has a collar portion (16a 1, 16b 1) which is used as a contact surface for a relevant spring element (18a, 18b); and - a plurality of spring elements (18a, 18b), wherein each of the spring elements (18a, 18b) is arranged in one of the chambers (14a, 14b) in the housing and is supported on the collar portion (16a 1, 16b 1) of the piston part (16a, 16b) associated with said chamber (14a, 14b) and on one of the intermediate walls or the end wall opposite the through-opening of the housing; wherein the collar portions (16a 1, 16b 1) of the piston parts (16a, 16b) each end flush with the inner wall of the housing, such an actuation space (20a, 20b) is formed in each case by one of the collar portions (16a 1, 16b 1), the corresponding piston part (16a, 16b), the inner wall and one of the intermediate walls or the end wall of the housing that has the through-opening; wherein each of the actuation spaces (20a, 20b) is provided with a pressure medium connection (22a, 22b) and the actuating system further comprises a pressure medium assembly which is designed to selectively supply the actuation spaces (20a, 20b) with pressure medium, wherein the spring elements (18a, 18b) acting on the different piston parts (16a, 16b) are designed to exert a relevant spring force in the same direction. - a housing which on one side comprises a through-opening for a piston and which is internally divided into a plurality of chambers (14a, 14b) by at least one intermediate wall which is perforated in portions; - a multi-part piston, wherein each of the piston parts (16a, 16b) is substantially accommodated in one of the chambers (14a, 14b) in the housing and only projects only in portions through the relevant opening in an intermediate wall delimiting the chamber (14a, 14b) or through the through-opening and has a collar portion (16a 1, 16b 1) which is used as a contact surface for a relevant spring element (18a, 18b); and - a plurality of spring elements (18a, 18b), wherein each of the spring elements (18a, 18b) is arranged in one of the chambers (14a, 14b) in the housing and is supported on the collar portion (16a 1, 16b 1) of the piston part (16a, 16b) associated with said chamber (14a, 14b) and on one of the intermediate walls or the end wall opposite the through-opening of the housing; wherein the collar portions (16a 1, 16b 1) of the piston parts (16a, 16b) each end flush with the inner wall of the housing, such an actuation space (20a, 20b) is formed in each case by one of the collar portions (16a 1, 16b 1), the corresponding piston part (16a, 16b), the inner wall and one of the intermediate walls or the end wall of the housing that has the through-opening; wherein each of the actuation spaces (20a, 20b) is provided with a pressure medium connection (22a, 22b) and the actuating system further comprises a pressure medium assembly which is designed to selectively supply the actuation spaces (20a, 20b) with pressure medium, wherein the spring elements (18a, 18b) acting on the different piston parts (16a, 16b) are designed to exert a relevant spring force in the same direction. wherein the collar portions (16a 1, 16b 1) of the piston parts (16a, 16b) each end flush with the inner wall of the housing, such an actuation space (20a, 20b) is formed in each case by one of the collar portions (16a 1, 16b 1), the corresponding piston part (16a, 16b), the inner wall and one of the intermediate walls or the end wall of the housing that has the through-opening; wherein each of the actuation spaces (20a, 20b) is provided with a pressure medium connection (22a, 22b) and the actuating system further comprises a pressure medium assembly which is designed to selectively supply the actuation spaces (20a, 20b) with pressure medium, wherein the spring elements (18a, 18b) acting on the different piston parts (16a, 16b) are designed to exert a relevant spring force in the same direction.