Curved escalator

A curved escalator having:

• guide rails defining a stairway path,
• a plurality of segment-shaped steps movable along the stairway path,
• a step axle carrying each step, and
• an inner and an outer endless loop of step chains connected to the step axles and driven by sprocket wheels on sprocket shafts at upper and lower turn-around portions, the sprocket wheels having teeth formed by first recessed portions in which each step axle is received and second recessed portions between the first recessed portions, the step axles being inclined at an angle and turning around a conical surface at the upper and lower turn-around portions so that said steps circulate along the endless loops,
• each step chain including:
• joint pieces and link members,
• each joint piece being engaged with an end part of one of said step axles,
• said link members having one end part connected with one end part of one of said joint pieces,
• said link members including rollers,
• means including a spherical roller and bearing providing a spherical joint connecting said end part of each joint piece to said one end part of each link member in a threedimensionally deflectable manner so as to allow said step axles to be disposed at an angle to said step chains in the turn-around portions, thus reducing the force exerted on said step chains,
• said spherical joint including a first roller having a spherical exterior surface and mounted on said one end part of said joint piece, a second roller having an interior surface matching the exterior surface of said first roller and mounted on said one end part of the connected link member, whereby said interior surface of said second roller and said exterior surface of said first roller form a sliding surface of said joint,
• bottom surfaces of the first recessed portions of the sprocket wheels being between respective teeth and sloped relative to the sprocket shafts so as to conform to the angle of the step axles in the turn-around portions and allow smooth transmission of driving force to the step axles,
• each of said step axles having:
• a roller mount rotatably mounted on an end of said step axle,
• a guide roller rotatably mounted on said roller mount, said guide roller being rotatable about an axis perpendicular to and intersecting the longitudinal axis of said step axle and being engageable with one of said guide rails, and
• drive rollers mounted on both sides of said guide roller, said drive rollers each being rotatable about an axis parallel to said step axle and being engageable with one of said guide rails, whereby the position of said roller mount is regulated by said drive rollers to restict the angle of inclination of said guide roller and minimize slippage of said guide roller on the cooperating guide rail while allowing the steps to be kept horizontal while moved smoothly along the stairway path.