Abstract: A bumper for a motorcar having a shock absorbing member made of a foamed synthetic resin attached to a front surface of a backup beam connected to left and right stays of a car body. The resultant assembly of those members is covered at its front, upper and lower surfaces with a synthetic resin facing member which is nearly in the form of a channel in section. The backup beam is formed out of fiber-reinforced synthetic resin and is a hollow beam member having depth which is comparatively large at its middle portion extending between the two stays and is comparatively small at its both end portions extending from the two stay connecting portions thereof to the terminal ends thereof. The shock absorbing member is formed so that the change in the depth thereof is in inverse relation to the foregoing change in the depth of the backup beam so that the depth of the entire resultant assembly may nearly constant.

Abstract: A four-wheel drive system has a center differential between front and rear wheels, and means for restraining or locking the center differential. The four-wheel drive system is equipped with an automatic control system for automatically locking the center differential when a coefficient of friction between a road surface and a tire of at least one wheel is equal to or lower than a predetermined value. The coefficient of friction is determined by sensing a steering angle, a vehicle speed, a normal load and a steering force, or by sensing an ambient temperature and a humidity. The control system may be arranged to lock the center differential only when the vehicle speed is equal to or lower than a predetermined speed.

Abstract: A part-time type four-wheel drive system has a 2WD-4WD changeover means capable of changing the drive system from a four-wheel drive mode to a two-wheel drive mode and vice versa. The four-wheel drive system is equipped with a control system for automatically changing the drive system from the four-wheel drive mode to the two-wheel drive mode by commanding the changeover means when a steering angle of the vehicle becomes equal to or larger than a predetermined angle. The control system may has a vehicle speed sensor. In this case, the control system changes the drive system from the four-wheel drive mode to the two-wheel drive mode only when the vehicle speed is equal to or lower than a predetermined speed.

Abstract: A part-time type four-wheel drive vehicle has automatic locking clutches which are automatically engaged to connect the front wheels with their axle shafts when the vehicle is moved in the four-wheel drive mode, and can be disengaged by rotating the axle shafts in the reverse direction in the two-wheel drive mode. The vehicle is further provided with a rotation sensor for sensing a rotation of the front propeller shaft or other member for driving the front wheels, and an indicator for informing the driver of the engagement of the automatic locking clutches if the front propeller shaft is rotating. The vehicle may be further provided with a vehicle movement sensor.