Linear motion guide unit

A linear motion guide unit, comprising:

• an elongated guide rail having two sides, each side having a pair of first raceway surfaces extending lengthwise of the guide rail, and
• a slider that fits over or conforms to the elongated rail for movement in a sliding manner relative to the elongated guide rail;
• wherein the slider has a carriage, end caps, end seals, and a plurality of rolling elements,
• the carriage having a pair of second raceway surfaces extending in opposition to the pair of first raceway surfaces on the guide rail to provide a pair of load-carrying races between the pair of first raceway surfaces and the pair of second raceway surfaces, and
• a pair of return passages extending along the pair of load-carrying races,
• the end caps being fastened on forward and aft end surfaces of the carriage, one to each end surface, and provided therein with turnaround passages to join together the pair of load-carrying races and the pair of return passages,
• the end seals being attached on outward end surfaces of the end caps, and
• rollers selected as the rolling elements which are allowed to roll through circulating circuits made up of the pair of load-carrying races, the pair of return passages and the turnaround passages;
• wherein each of the end caps has an inward end surface facing directly towards the end surface of the carriage, and having a concavity which extends into the inward end surface and a pair of openings communicating with each of the turnaround passages, and
• a porous compact impregnated with lubricant and fitted into the concavity in a fashion exposed in part to the turnaround passages through the openings so that the rolling element rolling through the turnaround passages, as coming into rolling-contact with at least one of the parts of the porous compact exposed out of the openings, are applied with the lubricant;
• and
• wherein the end cap has a pair of spacer parts to form inside curved surfaces of the turnaround passages, and an end cap major body to form outside curved surfaces of the turnaround passages,
• the pair of spacer parts being made up of first spacer parts fitted into the end cap major body and second spacer parts nested in the first spacer parts,
• the first spacer parts and the second spacer parts being in combination with each other to provide curved zones to change running direction of the rolling elements and straight zones integral with opposite ends of the curved zones and merged into the pair of return passages, and
• the straight zones having slots at ends each of which fits over a part of the porous compact, and the slots terminating in the openings through which the porous compact is exposed at the straight zones to the inside curved surfaces of the turnaround passages.