It is not the first century that Jess Reno's miracle stairs have made it easier for us to walk. And although the initial task of escalators was to transport powerful passenger flows in subways, train stations and major markets, if the appropriate means are available, there are no fundamental restrictions for their use in a wide variety of premises and outside them. Against the backdrop of crystal chandeliers and heated garden paths, this is not much of a luxury. And in some cases - in medical institutions or apartments with disabled people, in offices whose staff is forced to constantly move from floor to floor, in rooms where continuous cyclic inspection is performed (for example, electrical installations located on different floors) by the personnel on duty - and at all an absolutely necessary device. Elevators, although they require less space and money, cannot be compared with escalators in terms of convenience,efficiency and bandwidth.
At present, escalators are industrially produced in lengths from 3 to 75 meters and cost, respectively, from several thousand to one million US dollars. Their load capacity, speed and smoothness of movement, length, width and height of steps, climatic performance, noise characteristics, decoration, lighting, design details also vary within wide limits. The tilt angle can be up to 35 degrees for relatively low lift heights (up to 7 meters) and 30 degrees for long escalators.
Thus, you can always choose (or order an exclusive) mechanism for any conceivable application: connecting floors or terraces in a park, lifting people to the head of a statue being examined or from a pool water … It is difficult to recommend such a complex engineering structure for homemade production (although history knows cases, when the planes were going alone in the garage). But a brief overview of the technical problems encountered in the design and maintenance of escalators will also help when buying a ready-made one: it is always useful to know which parameters to pay attention to and what determines the cost of the product.
The classic design of the escalator is a set of trolley steps, mounted on a traction chain in such a way that each step carries the load only from the weight of people directly on it, and the total effort falls on the chain and reaches its maximum at its highest point. A special force acting on both the chain and the undercarriage of the bogies occurs when it bends around the drive sprocket and significantly exceeds the average tension from the payload. It is inversely proportional to the link length and bend radius. Likewise, the longitudinal "jitter" depends on these parameters, reducing the comfort of passengers and the service life of the escalator. However, the link length cannot be reduced for strength reasons. As a result, on large escalators, the drive sprocket diameter exceeds 2 meters. Therefore, a huge torque is required on the shaft,which means a huge gearbox.
The trolley step itself must withstand a force of over 600 kg (at the bend of the chain). Moreover, the total backlash of its moving parts cannot exceed 0.4 mm. As a result, the cost of one step of an ordinary metro escalator (ET-2, ET-3) is about 10,000 rubles.
Of course, almost all of the problems outlined are greatly simplified when moving to smaller sizes and capacities. When the length of the escalator is measured not in tens, but in units of meters, the design load is not 2 people for each step, but 5 people in total … This changes things. Up to the transition from quantitative to qualitative changes: instead of rumbling chains and metal carts, there are polymer parts (light, cheap, in many cases do not require lubrication), instead of jerking gears, smooth clutches, and so on. Even with a purely quantitative (without changing the schematic diagram) decrease in the load capacity and length by 2 times, the power consumed by the escalator decreases by 4-5 times, the cost - by about 4 times. But if you get into a qualitative leap, changes are measured in orders.
Even more fundamental changes in design (and price) occur with the transition to angles of rise less than 12-15 degrees. At the same time, it is possible to completely abandon the steps. Such mechanisms are called travolators or (at very small angles) passenger conveyors. Their working blade is a flat (of course, with a large roughness and non-slippery coating) polymer or hinged metal tape. Often (with an appropriate distance to walls and surrounding objects), handrails can not be used on travolators. In many cases, they are more convenient than escalators (when transporting goods, carts, baby strollers and wheelchairs), more economical and quieter. The only drawback is that they take up a large area to ensure lifting to the same height, and are used accordinglyonly in huge rooms or in open spaces, except for those cases when the difference in the height of the connected levels is quite insignificant.