Variable displacement axial piston device

摘要

Variable displacement axial piston device having a rotating cylinder block (120)comprises a trunnion type movable swash plate (150) supported in a rotatably sliding manner by a bearing portion (205). With the aim of reducing the rotating frictional resistance in said bearing portion (205) two embodiments of swash plate (150) are presented. In a first embodiment an outer circumferential surface of a trunnion shaft (160) includes at least one suction groove (162) that forms a pocket portion (162a) between the suction groove (162) and the inner surface of the bearing portion (205). The pocket portion (162a) is opened to an inner space of housing on at least one side in an axis line direction of the trunnion shaft (160). In a second embodiment an outer circumferential surface of the trunnion shaft (160) includes a large diameter portion (165) at a middle part, an outer side small diameter portion (166a) and an inner side small diameter portion (166b).