Abstract: The inner surface of an outer cylinder is made an outer cylinder raceway having a simple circular sectional configuration having a radius of curvature. On the outer circumference of an inner cylinder, a plurality of grooves having the radius of curvatures dimensioned equally to the aforesaid radius of curvature are arranged extendedly at the same pitch. The outer circumference of barrel shaped rollers inserted between the grooves and the inner surface of the outer cylinder is dimensioned equally to the aforesaid radius of curvature. The barrel shaped rollers and the inner and outer raceways constitute linear contacts, thus enhancing the ability of the load resistance to make it possible to prevent the peeling off, cracking, and other damages from taking place by the heavy load to be applied.

Abstract: A vehicle mounted obstacle detecting radar is disclosed. An electromagnetic wave radiated from the radar apparatus is received by a first antenna mounted on the ground and passed through a transmission line to a second antenna mounted on the ground and radiated thereby to a monitor area. A response electromagnetic wave from an obstacle within the monitor area is received by the second antenna and passed through the transmission line to the first antenna and received by the radar apparatus. When the transmission channel is arranged along a curved road, an obstacle in the curved road can be detected.