Crawler unit and trolley for bad road using the same

A crawler unit comprising a crawler that circulates around a plurality of pulleys rotatably attached to a frame, wherein

• the crawler includes a plurality of inner attachments provided inside thereof toward the frame to have a band-shape,
• the crawler unit is provided with:
• a pair of overhang edges of a rail provided on a circumference of the frame, the overhang edges of the rail protruding in a left and right direction of the rail;
• and
• a pair of overhang edges of each of the inner attachments, the overhang edges of each of the inner attachments protruding from an outside of the pair of overhang edges of the rail in a left and right direction of each of the inner attachments,
• in a space enclosed by the pair of overhang edges of each of the inner attachments the pair of overhang edges of the rail are inserted,
• the pair of the overhang edges of the rail and the pair of the overhang edges of each of the inner attachments are set in a positional relation in which the pair of overhang edges of the rail and the pair of overhang edges of the inner attachments overlap with each other in an up and down direction, and
• the crawler circulates around the pulleys while the inner attachments are restricted along the rail, wherein
• the rail is provided only at an outer peripheral bottom portion of the frame, and
• portions near both ends of the rail are curved and open in a downward direction.