Sliding-assistance unit for a linear motion apparatus

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.