An apparatus (10) includes a traction member in the form of a roller (24) configured for mounting on a body (12) so as to permit rotation of the roller (24) relative to the body (12). The roller (24) is mountable on the body (12) so as to define a skew angle relative to a longitudinal axis (26) of the body (12). In use, the roller (24) engages a wall of a borehole or bore-lining tubular and the roller (24) urges the apparatus (10) along the wall of the borehole or bore-lining tubular on rotation of the as the roller (24) rotates on the body (12).