Patient transport apparatus for traversing stairs

A patient transport apparatus operable by a user for transporting a patient, the patient transport apparatus comprising:

• a support structure having a front strut and a rear upright;
• a seat section for supporting the patient, the seat section being pivotably coupled to the support structure about a rear seat axis;
• a front wheel operatively attached to the front strut;
• and
• a carrier assembly arranged for movement relative to the support structure between a chair configuration for traversing floor surfaces and a stair configuration for traversing stairs, the carrier assembly comprising:
• a shaft defining a wheel axis,
• a rear wheel supported for rotation about the wheel axis,
• a track assembly having a belt, and
• a hub supporting the shaft and the track assembly for concurrent pivoting movement about a hub axis defined by the rear upright, the hub axis extending through a reference plane intersecting the rear seat axis and fixed relative to the rear upright, the reference plane defining opposing first and second longitudinal sides;
• wherein movement of the carrier assembly from the chair configuration to the stair configuration simultaneously deploys the track assembly for engaging stairs and moves the wheel axis from the first longitudinal side of the reference plane to the second longitudinal side of the reference plane to bring the rear wheel closer to the front wheel;
• wherein the seat section is pivotably coupled to the front strut about a front seat axis;
• wherein the support structure further comprises an intermediate arm pivotably coupled to the front strut about a front arm axis and pivotably coupled to the rear upright about a rear arm axis;
• and
• wherein the rear arm axis is substantially parallel to the hub axis and extends through the reference plane.