The 4WD vehicle has free-wheels. A changeover gearbox is provided with a shifting device to change between two wheel drive and four wheel drive. A free-wheel hub device to release each of the driven wheels by induction vacuum in a two wheel drive gearbox operating state is located between each of the driven wheels and a drive-side axle. The free-wheel device is equipped with sealing elements to maintain a vacuum path in a hermetically sealed state, comprising a vacuum intake channel, a vacuum changeover valve (126) to open and close this channel and a time transmitter to operate it so that the channel is opened to the atmosphere after the elapse of a certain time from the moment when the gearbox changes to two wheel drive or four-wheel drive until the moment when the induction vacuum becomes constant.
