A new crane arrives on the island, Rocky. Rocky has no engine and is unable to move on his own. Edward dismisses Rocky as new fangled nonsense. When Edward causes a spillage of telegraph poles on the tracks, he calls for Harvey - the smaller crane. But Harvey isn't fast enough and Gordon steams into the poles and crashes. Harvey can't lift Gordon and Edward realizes that only Rocky is big enough to help. Edward realizes that Rocky is useful after all and is proud to be his friend.

Source: PBS summary for "Big And Small"