JTEKT Corporation has developed a “Rocker Roller” (※1) bearing for automotive roller rocker arms that displays low torque and does not cause damage to cams.

  In recent years automakers increasingly have adopted low-viscosity engine oils in order to improve fuel efficiency, and because slippage accompanies the rolling contact occurring between the cam and bearing outer ring in the case of roller rocker arm bearings used in such low-viscosity oils, the outer ring must have sufficient hardness. To obtain such hardness, conventionally a “shot blast” process to improve surface-layer fatigue strength and a “barrel” process to reduce surface roughness have been used. However, this shot blast process causes surface roughness that may not be adequately removed by the barrel process, which can result in increased torque and, in the case of low-hardness cams, cam damage.

  To resolve this problem, JTEKT developed a special “Tetratekt” (※1) barrel process that both hardens the surface top layer?eliminating the need for the shot blast process?and removes surface roughness. By means of this special process, JTEKT is able to manufacture Rocker Roller bearings for roller rocker arms that displays low torque and do not damage the cam.

  JTEKT aims to achieve sales of one million units per month in 2008 of automotive engine bearings manufactured by this Tetratekt barrel process and is studying the possibility of utilizing this technology in the manufacture of parts other than automotive engine parts involving slippage.

  ※1　The Japanese-language equivalents of "Rocker Roller" (ロッカローラ) and "Tetratekt" (テトラテクト) are registered trademarks of JTEKT in Japan.