Abstract: An improved rotor end winding assembly for an electrodynamic apparatus includes a stack of conductive straps that are configured to turn about an end turn portion of a rotor and include a top strap, a bottom strap and a number of intermediate straps that are stacked between the top strap and the bottom strap. A space defined between the rotor shaft and the bottom strap is divided into a high pressure zone and a low pressure zone by a zone block. A stepped coolant passage defined in the stack includes an ascending passage that leads from the high pressure zone toward the top strap and in the direction of the zone block and low pressure zone, and a descending passage that leads from the ascending passage to the low pressure zone. As a result, coolant will flow from the high pressure zone to said low pressure zone to efficiently cool said stack of straps.