A traction device includes a continuous traction belt provided on a pair of opposing rollers. The traction belt includes openings such that a vacuum may be applied through the traction belt causing the traction device to cling to a working surface. A motor may be provided to drive one of the rollers and thereby drive the belt. A plurality of such traction devices may be coupled with a control mechanism to form a robot. A system is described for performing work or maintenance on a structure having an inclined working surface that includes a support robot for positioning at a high point on the structure and a payload robot attached to the support robot by an umbilical or tension cord for maneuvering along the working surface.