Upper rail for passenger conveyor

A passenger conveyor comprising:

• a drive motor including a drive shaft,
• a drive sprocket coupled to the shaft of the drive motor,
• a drive terminal gear coaxially engaged with the drive sprocket,
• a step chain meshed with the drive terminal gear so as to be driven thereby,
• at least one step connected to the step chain and having first and second wheel rollers provided at opposite sides thereof, and
• an upper rail for guiding the first wheel roller so that the step chain meshes smoothly with the drive terminal gear,
• wherein the upper rail comprises a straight section and an arched section extending from an end of the straight section,
• wherein a location at which the arched section starts and the straight section terminates is located at or beyond a perpendicular center line of the terminal gear,
• wherein a distance from an upper surface of the straight section to a circumferencial surface of the terminal gear is shorter than a radius of the front wheel roller.