A linear motion guide unit is disclosed in which a rack-and-pinion arrangement
is interposed between paired guide rails to keep a cage retaining more than one
rolling element therein against falling off from the guide rails. In the linear
motion guide unit, the cage arranged between confronting raceway grooves of the
guide rails hold therein a pinion, which comes in mating with a rack lying in the
raceway grooves. The cage is made therein with an aperture in which a thick portion
of a pinion holder fits to secure the pinion holder to the cage. The pinion is
comprised of a disc having teeth that come in mating with the rack, and a shaft
serving as an axis about which the disc rotates. The pinion is held in the pinion
holder, with the shaft being carried for rotation in pinion chamber in the pinion holder.
