An apparatus for rotatably mounting and axially fixing a gear on a shaft comprises a bushing fixed within a bore of the gear. A sleeve is received on and fixed relative to the shaft. The sleeve is surrounded by and journalled for rotation within the bushing. A thrust ring is fixed relative to and projects radially from the shaft on one side of the gear. A retainer on the one side of the gear defines a circular channel within which the annular thrust ring is axially confined.