Abstract: A hydraulic machine includes a support structure and a rotating group rotatably mounted relative to the support structure. The rotating group includes a shaft and a cylinder barrel with a plurality of circumferentially spaced cylinder bores. Reciprocal pistons extend from the shaft with each one of the pistons extending into an associated one of the cylinder bores. A joining assembly joins the shaft and the cylinder barrel so that the shaft and the cylinder barrel rotate together. The hydraulic machine further includes at least one oil dam associated with the rotating group and adapted to trap hydraulic fluid used for lubricating portions of the joining assembly.