A retractable arm assembly for use in positioning a milker arm near the teats of a cow is disclosed. The retractable arm assembly allows a milker claw to be stored above a milking platform in a clean, safe position, and then automatically extended to the milking position and maintained in that position until the milker claw has been removed from the teats of the cow. The retractable arm assembly includes a movable milker arm having an interior chamber for receiving a chain to which the milker claw attaches. A lever arm connected to the milker arm faciliates movement of the milker arm in a downward and outward path around and behind the cow's rear leg. Both the chain and the milker arm can be selectively extended and retracted.