Abstract: This linear motion rolling guide unit is able to detect the relative positions and so forth of a track rail and slider by forming narrow grooves 21e in track rail 21 and arranging extremely narrow, linear scales 31 and 32 in those grooves. Thus, it is easy to reduce the size of this linear motion rolling guide unit, it is able to flexibly accommodate the particular conditions of use, and it is also inexpensive.

Abstract: A position detection apparatus having a scale with resilient engaging portions that attach to a lower surface of the scale and engage insertion holes in a track rail into which fastening members are inserted for fixing the track rail to a bed. Also, a track rail unit that includes the position detection apparatus, and a guide unit that includes the track rail unit.

Abstract: A top cover is disclosed that is able to reduce the number of processing steps required for processing and assembly of the entire guide unit into which the top cover itself is included as one of its parts, contribute to reduced costs, facilitate easy attachment and removal to and from a track rail, and be installed on various types of track rails that have already been installed on a machine tool and so forth. In addition, a track rail unit is disclosed that is composed by combining the top cover and track rail, and a guide unit is disclosed that contains the track rail unit.The above effects are obtained by using fastening member insertion holes formed in a track rail, and employing a top cover having an engaging portion that elastically fits into those insertion holes.