Escalators are a popular means of transporting people up and down the stairs. These platforms can be made of metal, sandwich panels or glass and are designed to be very durable.
A key component of an escalator is the step chain. This chain is used to guide the steps and is installed inside the truss of the escalator.
Escalators are moving platforms that travel in an upward and downward direction, and may traverse vertical distances of up to 18 metres (60 ft). They can be found in airports, convention centres, hotels, department stores, public buildings, shopping malls and transit systems.
Most modern escalators have single-piece aluminum or stainless steel steps that move on a system of tracks in a continuous loop. The steps are linked by a continuous metal chain and have either smooth risers or cleated treads with comb-like protrusions that mesh with the comb plates on the top and bottom platform.
The steps are attached to a series of drive gears at the top and bottom of the escalator, and are powered by an electric motor. As the steps are moved up and down, they flatten out so that passengers can step on them easily and safely.
To do this, the chains on the front and back of each step are positioned in such a way that they can pass through a curved section of track at the top and bottom of the escalator without slipping. At the bottom of this curved section, the chains converge and the steps assume a staircase configuration. Then they travel down along the underside of a truss until they reach their final destination at the bottom landing.
This is done by adjusting the chain pitch. The higher the pitch, the lower the number of links per step or pallet. Moreover, it reduces the cost and wear.
One problem with conventional escalators is that they have a relatively small chain pitch and a large number of teeth in the chain wheels. This results in a high number of positions per step or pallet, which can be costly and wear out quickly.
In some escalators, however, there is a solution to this problem. This is called the “polygonally-compensated” escalator design, described in European Patent Application EP 1 344 740 A1.
With this design, the first strand is driven with a polygonally-compensated escalator chain entry angle while the second strand runs in an irregular manner. This causes the lower strand to apply forces to the upper strand, which in turn cause the escalator to flex.
Flattening the Steps
There are a number of factors that determine the design of an escalator, including physical requirements, location, traffic patterns, safety considerations and aesthetics. One of these factors is the stair configuration.
Escalators have steps, which can be solid or hollow. The solid stairs are typically made from steel or aluminum. They are cleated with comb-like protrusions that mesh with the bottom and top platform comb plates. The combs are also designed to catch any items that might come in contact with them, such as stones, screws or popcorn.
In addition to the combs, a set of struts, also called a truss, runs along the underside of the escalator truss to support the steps. These struts are positioned at the top and bottom of each step. The struts are designed to provide a smooth transition between the escalator’s landing and the constant slope intermediate zone.
Each step has two sets of wheels, which rotate around a track that is mounted on the underside of the escalator’s truss. The first set of wheels are near the top of each step, and the second set of wheels are near the bottom.
These wheels are connected to a rotating chain that is pulled by a drive gear at the top of each step. As the steps move from top to bottom and back to top, their curved shape causes them to flatten out.
The curved path of travel is a unique feature of a curved escalator. This is because a curved escalator has a fixed center, constant radius arc when viewed in plan.
However, this curved path of travel can be challenging to maintain. This is especially true for escalators that are designed to pass through a curved section of track before reaching the bottom landing.
To overcome this problem, an escalator of the present invention includes a track splice. The splice is preferably positioned in a dip zone, which is in the form of an S curve that smoothly carries the rollers as they advance toward the inner sprocket. This type of dip zone is able to accommodate side thrust rollers as well as standard rollers on the escalator’s steps.
Moving the Handrails
Escalators have moving handrails in addition to the moving steps to provide riders with a smooth and safe ride. The handrails are usually a rubber conveyer belt looped around a series of wheels that are precisely configured so they move at the same speed as the steps, to help riders maintain their balance.
The handrails are designed to move at the same speed as the stairs, but sometimes slippage or normal wear and tear can cause the handrails to move at a slightly different speed than the steps. This can make it difficult for riders to keep their balance when stepping on and off the escalator.
Many escalators today use a motor to move the steps and the handrails along a system of tracks. The motor uses a chain that carries the motive force from a main drive shaft to the handrail drive shaft.
Some escalators have the handrail drive incorporated within the truss, whereas others have it separate from the truss. This allows for a more compact installation that does not require a full replacement of the escalator.
Another option is to replace the entire handrail assembly with new handrails that are designed to match the aesthetic of the escalator. This can improve the overall appearance of the escalator, making it more appealing to commuters and tenants.
As the handrails on an escalator are driven by the same motor as the steps, it is common to see an increase in the amount of wear and tear that occurs on the handrails over time. This can be a problem on older escalators that have seen heavy foot traffic like airports, shopping malls or large commercial buildings.
One solution to this issue is to replace the handrail drive wheel with a newer model that has a larger rubber tread. This will reduce the wear and tear on the rubber and make the handrails move more smoothly with less effort.
The handrail drive is also typically made from a metal or a plastic material that is covered in a rubber coating to protect the handrail and prevent slippage. The newer models can be installed in just about any escalator, and they are much more durable than the old handrails that were often made from rubber bellows with rings of steel cladding in between each coil.
In a motorized escalator, the main chain loops are turned by an electric motor. The motor also powers escalator chain a handrail that is looped around a series of wheels and is configured so that it moves at a similar speed to the steps.
The escalator chain is made of a combination of steel and a high-quality rubber compound. It is designed to withstand a large amount of pressure and stretch without breaking or fraying.
This is accomplished through careful planning and design and the use of the right materials. It is also important to keep the escalator chain clean and free of dirt and dust.
Ideally, the escalator chain should be lubricated automatically to help extend its life and ensure optimum performance. This can be done by installing a lubrication system that runs periodically to lubricate the drive chain, handrail drive chain, and step chain.
The primary reason why the escalator chain needs to be lubricated is that it is subjected to significant stress when in motion. This stress is caused by impact with other parts of the escalator and the surroundings, which can be a major cause of mechanical failure.
A major source of these impacts occurs in the reversing of the drive chains. These impacts can create a polygon effect and damage the chain, the sprockets and the gearbox outputs.
For avoiding the polygon effect, the reversing of the drive chains should be performed in a sequence of steps that is matched to the number of steps. This is done by articulating each step chain end at one or more joints, and the joint areas should be in contact with each chain wheel for a sufficient period of time to prevent polygon effects from developing.
This is a particularly good solution for escalators and moving walks, which are commonly seen in department stores or other commercial environments, and which may have relatively low forces. However, even in these circumstances, the existing polygon effects should be avoided because they result in additional wear and tear on the reversing chain.
The reversing of the escalator chain should be performed in two stages: first, the reversing chain is put into position and then it is rotated to reverse the escalator chain. This allows for the reversing of the escalator’s chain to take place while keeping the passengers safe.