PURPOSE: To disassemble and maintain a swash plate without disassembling the whole of a motor by fixing a bearing block to support a trunnion shaft of the swash plate on an inside deep bottom part of a swash plate chamber from an opening of a main body case free to connect and disconnect.

CONSTITUTION: A pair of trunnion shafts 16 having an axis Y orthogonal with a motor axis X at the center of a swash plate pressure receiving surface is projectively provided at an outer peripheral diagonal position of a swash plate 9, and a pair of bearing blocks 17 to internally fit and support each of the trunnion shafts 16 free to rotate is bolt-fixed on the inside deep bottom surface of a driving chamber D free to connect and disconnect. These bearing blocks 17 are inserted into a recessed part Da formed on the inner peripheral surface of a swash plate chamber, and the recessed part Da is used as a detent of a pressure plate 23 for braking. At the time of disassembling and maintaining the swash plate 9, bolt fixture of the bearing blocks 17 is released by removing a hydraulic block 3, extracting a cylinder block 7 from a rotation shaft 5 and exposing the swash plate 9.