Abstract: To permit constructing flexible belt-rack longitudinal-movement structures of substantial length, not subject to vibration, and inexpensively built, the rack (3) is cast integrally with a slab (2) of plastic concrete. A stiffening rib (33) can be provided in the slab, preferably at the side remote from the movable machine element (7), and preferably formed with a through-bore to attach a tension rod therethrough, so that a plurality of such slabs can be longitudinally connected together. Guide rails (5) are located at the sides of the slab, on which slide bearings (6) are located which, in turn, support a movable carriage, movable along the bed. The carriage carries the drive motor (17) which drives a gear belt (22) for engagement with the rack.

Abstract: To facilitate manufacture of accurately formed tracks (6) within a circulating nut (10) on a spindle (1), the nut is formed with insert strips (4) shaped to receive the balls (3), the insert strips defining said track and, for example, being formed as part semi-circular trough-like sheet steel elements bent into spiral form, with circulating return portions (7) for the balls formed in either the nut, or extending from, and joining adjacent terminal portions of the strips. To prevent loss of balls, an elastic, e.g. plastic tape (189) with laterally projecting wings (19) is positioned between the tracks (6) defined by adjacent strips, partly overlapping the balls (3) in the tracks, additionally providing reservoirs for lubricant and excluding contamination of the track within the nut by dirt, grit and the like.

Abstract: A stiff, form-stable elongated tubular housing (1) is formed with an axially extending longitudinal slit (12). A drive spindle (4) is retained in bearings (8) located in end flanges (2) of the housing, driven for example by a motor (M). A pair of spindle nuts (5, 6) clamp, between themselves, a tubular portion (15) of a force transfer element (14) which is located externally of the housing and moved by a web (13) passing through the slit. The force transfer element is guided on the housing by interengaging groove and projection means (20, 21), which also isolate forces applied to the force transfer element from the spindle drive.

Abstract: To form a protective cover for an elongated machine element, such as a feed spindle or the like (1), a tubular structure (7) which may be formed of a plurality of parallel strips (7a) has edges which are formed with an interengaging, interlocking but separable ridge or rib-groove construction (10, 9) similar to a slide fastener. To provide for secure interengagement and covering of a traveling element (2-4) on the spindle, a guide cone (16) is secured to the traveling element surrounding the tubular structure. The guide cone may include a hub (4) formed with a part-circumferential opening or openings (15) through which the opened guide tube portions can pass to permit the traveling element to move while providing continuous protection to the spindle upon movement thereof, the guide cone insuring reclosing of the rib-and-groove behind the movable element, and opening in advance thereof. The tube may be formed, in addition, with longitudinal guide grooves (23) in which closing elements can engage (FIGS. 8-11).