An assembly (12) for actuating a transmission brake (1) that has a transmission brake cylinder (7), at least one control valve (16, 17) for controlling pressurizing and/or exhausting of the transmission brake cylinder (7), and at least one pressure line (14) via which the at least one control valve (16, 17) is connected to the transmission brake cylinder (7) to supply a pressure medium (10) to and discharge the pressure medium (10) from a pressure chamber (9) of the transmission brake cylinder (7). The assembly (12) includes a quick-exhaust valve (15), which is arranged in the pressure line (14) between the transmission brake cylinder (7), and the at least one control valve (16, 17).