Patent ID: 7802921

Claim:
A sliding-assistant unit for a linear motion apparatus comprising: two roller rings being selectively mounted oppositely crossly around each other and each roller ring having a frame being an elongated ring, being resilient and having an elongated hole being formed through the frame; a sliding-assistance bar having an inner side; and an elongated opening being formed through the sliding-assistance bar; a mounting bar being parallel with the sliding-assistance bar; an exposing bridge connecting between the sliding-assistance bar and the mounting bar and cooperating with the sliding-assistance bar and the mounting bar to form a U-shaped mount having a width corresponding to a thickness of the frame; and a mounting head being parallel with the exposing bridge, protruding from the sliding-assistance bar and corresponding to the mounting bar and having two opposite outside surfaces; a proximal end; and a heading edge; a gap being formed between the mounting head and the mounting bar; and a roller groove being formed in and around the frame and having an opening; a head cover being mounted detachably on the mounting head, corresponding to and being selectively mounted in the U-shaped mount of the frame and having an end; and a side cover being elongated, being mounted detachably on the mounting bar and having an inner surface; an outer surface; and a receiving groove being formed in the inner surface of the side cover and having a bottom.