wish it were that simple, It's a large piece, like you would see under the back of a stagecoach, it has turned, tapered ends that are off center to the square center section of the axle. The tapered ends are critical as a cast iron skien ( basicaly a spindle for the wheel ) gets pressed over it.
get a 4x4 (or whatever size the chunk of wood is) and a drawknife... Likely thats how they built it originally...