Abstract: A rack shaft (110) is formed with a rolling face (110c) narrower than a face width of rack teeth (110a) on the opposite side with an axis line X of the rack shaft being interposed therebetween, and formed with a pair of oblique faces (110b) on both sides with the rolling face (110c) being interposed therebetween, there are further provided a cylindrical roller (123) rolling on the rolling face (110c) of the rack shaft (110) and a support device (120) pressing the cylindrical roller (123) toward the rack shaft (110), and hence the cylindrical roller (123) rolls on the rolling face (110c) when a steering force is transmitted to the rack shaft (110) from a pinion (103a), thereby making it possible to allow a movement of the rack shaft (110) in an axis-line direction with a smaller resisting force.

Abstract: A differential apparatus includes a differential casing, a pair of output side gears disposed in the differential casing, a differential mechanism distributing driving force of an engine, a clutch for operatively connecting the differential casing with the axles of the vehicle, an actuator for releasing the clutch from its connecting operation, and an urging member for causing the clutch to connect the differential casing with the axles of the vehicle. When the actuator is inactivated, the urging member serves to attain the connecting operation of the clutch. Therefore, even if the actuator is in a bad condition, four-wheel driving condition of the vehicle can be maintained. Therefore, the differential apparatus allows the vehicle to escape from a bad road.