Abstract: A linear motion rolling contact guide unit includes a rail, a slider comprised of a center block and a pair of front and rear end blocks, a plurality of rolling members interposed between the rail and the slider and a retainer plate mounted on the slider for providing an intended sealing effect. The end block is formed with an elongated slot and the retainer plate is provided with a projection engageable with the elongated slot such that the projection may move within the slot in the longitudinal direction over a predetermined distance. Thus, even if the retainer plate is comprised of a plastic material and thus expands or contracts relative to the slider for various reasons, such a change in size may be absorbed effectively so that the retainer plate is self-adjusted in position.

Abstract: In a process for the thermal cracking of a heavy hydrocarbon in a cylindrical reactor, a portion of the content material in the reactor is taken out and injected back into the reactor according to a specific procedure to form a "wet wall" or liquid curtain on the inner peripheral wall of the reactor, thereby preventing coking in the reactor. The apparatus includes a radially outwardly extending interior annular recess around an upper portion of the inner wall thereof and forming a part of said inner wall and plural means for tangentially injecting the recycled liquid into said recess.

Abstract: In a process for the thermal cracking of a heavy hydrocarbon in a cylindrical reactor, a portion of the content material in the reactor is taken out and injected back into the reactor according to a specific procedure to form a "wet wall" or liquid curtain on the inner peripheral wall of the reactor, thereby preventing coking in the reactor.

Abstract: A linear motion rolling contact guide unit includes a rail, a slider comprised of a center block and a pair of front and rear end blocks, a plurality of rolling members interposed between the rail and the slider and a retainer plate mounted on the slider for providing an intended sealing effect. The end block is formed with an elongated slot and the retainer plate is provided with a projection engageable with the elongated slot such that the projection may move within the slot in the longitudinal direction over a predetermined distance. Thus, even if the retainer plate is comprised of a plastic material and thus expands or contracts relative to the slider for various reasons, such a change in size mya be absorbed effectively so that the retainer plate is self-adjusted in position.