the present invention generally provides a reduced downtime maintenance apparatus and method for replacing and / or repairing a subassembly in sealing equipment for oil field use . the invention allows the removal of rotating portions of a rotary drilling head without having to remove non - rotating portions . the reduction in weight and size allows a more efficient repair and / or replacement of a principal wear component such as a packer . specifically , the packer in a rotary drilling head can be removed independent of bearings and other portions of the rotary drilling head . furthermore , because of the relatively small size and light weight , the packer can be removed typically without having to use a crane to lift a rotary bop and without disassembling portions of the drilling platform . in some embodiments , the packer can be removed with the drill pipe without additional equipment . furthermore , the packer can be removed remotely without necessitating manual disengagement typically needed below the platform . the invention also provides a fluid actuated system to maintain a pre - load system on the bearing .