A baler for making parallelepiped bales includes a planetary gear drive arrangement including a planet carrier coupled through an overrunning clutch for driving an output shaft which extends cross wise to a forward end of an elongate baling chamber. A plunger is mounted for reciprocating within the baling chamber for compressing crop into a bale, with a crank shaft arrangement being mounted for rotation with the output shaft and being coupled to the plunger by a connecting rod arrangement. When the gear drive arrangement is operating for effecting a compression stroke of the plunger, the overrunning clutch operates in a driving mode. When the gear drive arrangement is operating for effecting a reverse stroke of the plunger, the overrunning clutch operates in an overrunning mode so long as compressed crop is exerting a force on the plunger.