A multiple driven axle vehicle, such as a four-wheel drive recreational vehicle having its front, steerable wheels being optionally driven by providing double acting overrunning clutches in the hubs of the front wheels. A transmission mechanism is provided for driving the front, optionally driven wheels slower than the driving surface otherwise drives those wheels so that the slower driven wheels overrun and do not engage when the steerable wheels are turned as the vehicle is driven through a turn, thereby eliminating the need for a differential between the steerable wheels and between the front and rear wheels. The overrunning roller clutches of the optionally driven hubs desirably include an intermittent friction apparatus operative between the roller cage and the vehicle chassis to intermittently exert a force tending to retard rotation of the cage with respect to the chassis, thereby indexing the roller cage and rollers to the forward or reverse engagable position. The intermittent nature of the friction permits the roller cage and rollers to return to the central, neutral position when rotation of the cage with respect to the chassis stops. The roller clutches further include a generally cylindrical cam driven by the transmission and located radially inward of the rollers and roller cage. The cam surface includes a ridge associated with at least some of the rollers for inhibiting inertial movement of the rollers from the forward engagable position to the reverse engagable position, as for example during sudden braking.