an improved combined clutch and brake apparatus is disclosed having a pressure disk positioned on a hub between a brake thrust disk and a pneumatic cylinder . the present invention is configured to allow the apparatus to be efficiently serviced . the brake thrust disk forms an outer surface of the invented combined clutch and brake apparatus . a movable piston positioned in a casing of the pneumatic cylinder forms an external face of the invented combined clutch and brake apparatus . this arrangement allows failed sealing collars sealing the piston to the casing to be efficiently replaced . readily accessible screws also allow clearances between the pressure disk and the brake thrust disk and between the pressure disk and a clutch thrust ring to be efficiently maintained at optimal levels via stepless adjustment from either side of the invented combined clutch and brake mechanism or from both sides . this is particularly important because friction elements which engage the driven disks are subject to extensive wear and therefore continuously alter the clearances . finally , a bolt connecting the piston to the pressure disk allows the length the piston is free to travel to be efficiently adjusted as desired .