The Working Principle Escalator is a kind of continuous running equipment which is composed of a chain conveyor of special structure and belt conveyor of special structure. It has many advantages such as large transport capacity, continuously transport personnel. So the safety requirement is higher than other equipment. It is mainly used in public places with concentrated flow of people, such as shopping malls, clubs, stations, airports and wharfs.  Construction The main drive has sufficient strength and stiffness and various sprockets are fixed reliably on the shaft. Do flaw detection on the welded parts of the shaft. Sprocket adopts special carbon steel, after heat treatment, the surface hardness is reasonable subway projects often require to ensure the sprocket working life of more than 20 years. The length of the main drive chain should be moderate. If the main drive chain is too tight or too loose, the comfort of the passenger seat will be affected, that is, the movement value of the escalator will increase. Handrail belt running speed The running speed of the handrail belt is relative to the step and the allowable difference of the pedal is 0-+2%. Why the handrail belt must be faster than pedal? First, the above standards require that the speed of the handrail belt must be greater than or equal to the speed of the steps and pedals. Such requirement is to prevent to hold handrail in hand, won’t because the speed of handrail belt behind the speed of step or pedal and cause the human body to lean back and have an accident. Then people can hurt more when he fails backwards than when he fails forwards.