An actuator comprises: a housing which is provided with an opening; a slider which is installed so as to be movable relative to the housing; a drive means which is installed in the housing and which moves the slider; at least a pair of seal members which is disposed at the opening of the housing so as to face each other and which exhibits dust-proof and drip-proof functions by engaging with each other; and move-through members which are mounted to both sides of the slider in the movement direction thereof and which move through the pair of seal members. The move-through members each comprise: a move-through section which pushes apart the pair of seal members in the direction in which the pair is separated; a cover section which covers an expanded opening formed between the pair of seal members when the pair is pushed apart by the move-through section; and an opening restriction section which, when the pair of seal members is pushed apart from each other by the move-through section, restricts the amount of opening between the pair of seal members and in turn restricts the size of the expanded opening.

A linear motion guide unit includes a rail including a rail upper surface and a rail side surface each extending in a longitudinal direction and having a first raceway surface provided on the rail side surface, a sliding member relatively movably attached to the rail and including a sliding member lower surface facing the rail upper surface and a second raceway surface facing the first raceway surface, a plurality of rolling elements rolling on a load-carrying race constituted by the first and second raceway surfaces, a cover member covering the rail and the sliding member and including a first fastener extending in the longitudinal direction, a moving member arranged outside the cover member and moving together with the sliding member, and a connecting member connecting the sliding member to the moving member. The first fastener includes a first right side element extending along the longitudinal direction, a first left side element extending in the longitudinal direction along the first right side element and engageable with the first right side element, a first front slider attached to the first right side element and the first left side element and fixed to the sliding member and the moving member, and a first rear slider attached to the first right side element and the first left side element, spaced apart from the first front slider in the longitudinal direction, and fixed to the sliding member and the moving member. During movement of the sliding member and the moving member, the first front slider and the first rear slider each disengage the first right side element and the first left side element from each other while the slider moves in a direction opposite to a side where the other slider is located, and engage the first right side element and the first left side element with each other while the slider moves in a direction toward the side where the other slider is located. The connecting member includes a first support member arranged between the first front slider and the first rear slider in the longitudinal direction and supporting the moving member. As viewed from the rail upper surface side in a direction perpendicular to the longitudinal direction, a first opening region resulting from disengagement between the first right side element and the first left side element is placed in a position avoiding the rail.

An upper dustproof member of a linear guideway includes a connection segment and two floating dustproof segments that are respectively connected to two opposite sides of the connection segment. Each of the two floating dustproofing segments has a carrying bar and at least one rib that is connected to the carrying bar. In each of the two floating dustproofing segments, the carrying bar has two end portions each having a bevel arranged away from the at least one rib. When the bevels of the end portions of the upper dustproof member are respectively inserted into four tolerance slots of two end caps, each of the end portions and the corresponding end cap have a tolerance gap therebetween, so that a slanting surface of each of the bevels abuts against the corresponding tolerance slot, and each of the end portions is deformable toward the corresponding tolerance gap.

A linear transmission module is provided, including a slider body, two end caps, and two dustproof members. The two end caps are respectively arranged at two opposite ends of the slider body. Each of the end caps includes two assembly grooves extending through the end cap in a direction. The two dustproof members extend in a direction. One end of each of the dustproof members is assembled in an assembly groove of one of the end caps, and the other end of each of the dustproof members is assembled in an assembly groove of the other end cap. Each of the dustproof members includes a dustproof member body, a first contact portion, and a second contact portion. The first contact portion and the second contact portion are) respectively located on two opposite sides of the dustproof member body, protrude from the dustproof member body, and are in a symmetrical shape.