A catheter system including a housing and a drive mechanism supported by the housing is provided. The drive mechanism includes an engagement structure configured to engage and to impart movement to a guide wire. The engagement structure defines a path for the guide wire, and the engagement structure is moveable between an engaged position in which the engagement structure engages the guide wire and a disengaged position in which the engagement structure does not engage the guide wire. The catheter system includes a biasing element configured to bias the engagement structure toward the engaged position, and the biasing element is aligned generally parallel to the path defined by the engagement structure.