Abstract: In an epicycle reduction gear arrangement having a built-in hydraulic motor, a rotation drum formed with internal teeth is rotatably attached to an outer peripheral side of a hydraulic motor housing and a planetary gear is arranged between an output shaft of a hydraulic motor projecting and extending from the hydraulic motor housing and the internal teeth of the rotation drum to thereby rotate the rotation drum in a speed reduced manner. The hydraulic motor housing is provided with a shell portion to which the rotation drum is fitted through a rotation bearing and a carrier member carrying both ends of a planetary gear shaft and having an outer diameter less than an inner diameter of the rotation bearing, the carrier member being formed integrally to an outer end surface portion of the hydraulic motor housing.

Abstract: In an epicycle reduction gear having a built-in hydraulic motor, a rotation drum formed with internal tooth is rotatably attached to an outer peripheral side of a hydraulic motor housing and a planetary gear is arranged between an output shaft of a hydraulic motor projecting and extending from the hydraulic motor housing and the internal tooth of the rotation drum to thereby rotate the rotation drum in a speed reduced manner. The hydraulic motor housing is provided with a shell portion to which the rotation drum is fitted through a rotation bearing and a carrier member carrying both ends of a planetary gear shaft and having an outer diameter less than an inner diameter of the rotation bearing, the carrier member being formed integrally to an outer end surface portion of the hydraulic motor housing.