The Levytator - escalating into a third dimension

Materials World magazine
,
3 Jan 2011
The Levytator system uses a continuous loop of curved modules

An escalator capable of following freeform curves is the invention of
Jack Levy, Emeritus Professor of Mechanical Engineering at City
University London, UK. Here, he discusses the Levytator’s key features,
its development and what the future holds. 

Charles Seeberger invented the moving stairway, or escalator as we know it, in 1897. While there have been some improvements to its design over the last century – to the driving mechanism, for example – there has been little change to its basic operation. It is a two dimensional system with the return path of redundant steps moving underneath those in use. Years of travelling on the London Underground, however, prompted me to contemplate the possibility of a curved escalator and what this would look like if it was built from the ground up, using the technology and materials that are available today.

The result is the Levytator. The system uses a continuous loop of curved modules that can follow any path upwards, flatten and straighten out, and descend once more, all with passengers onboard.

Up, down and around

Although some curved escalators have been built in the past, these can only follow a single radius and are of the conventional design – with the return path underneath the working steps – limiting where and how they can be used. But the Levytator can be arranged in any configuration, with the up and down curvatures tailored to suit the environment and shape of the building.

This opens up new possibilities in hotel, airport, museum, theme park and commercial facility design, with the escalator now capable of echoing the organic shapes that we see in modern structures.

 


For example, a pedestrian bridge could be mechanised to take passengers over a road, river or railway on a single escalator. A long Levytator could be employed to provide a tour around an entertainment resort or replace multiple travelators – which are limited to straight runs – in an airport. The system could even be configured as a DNA-esque double helix in the offices of a bio-science organisation.

Aside from aesthetic considerations, the Levytator also offers several practical advantages over existing designs.

As all of the steps can be accessed from above, maintenance can be carried out much more easily. This promises to reduce costs and minimise downtime – an advantage that will be appreciated by anyone who has seen the disruption caused on the London Underground when an escalator requires overhaul or repair.

The new design also means that no excavation would be required when installing the Levytator, making it easy to add to existing structures. This could be particularly useful in the heritage sector, where it could be placed on top of a grand staircase in a listed stately home, providing better access for elderly and disabled visitors, without destroying the fabric of the building.

Step change

With the aid of a grant from the London Development Agency, a working model has been constructed to prove the concept. This is driven by a conventional electric motor and sprocket wheel. For the full-scale machine, a linear motor arrangement would be the preferred option. These are already commonly used in rollercoasters and amusement park rides – applications carrying passengers at much greater speeds.

The connection between one step and the next requires a bearing that will permit vertical movement and lateral rotation. In the working model, this is achieved simply using a linear bearing of a kind made robust using advances in materials. These would be suitable up to a rise sufficient for most existing escalator applications.

For higher rises, a different arrangement is necessary, similar to that used underneath the steps in existing escalators. This means that the steps move slightly from one another in the direction of travel, so that their risers need to be spherical rather than cylindrical to avoid leaving unacceptable gaps. Again, this is not a difficult manufacturing problem.

Side step

Every year there are thousands of accidents on escalators, including several deaths. Mainly, these are due to careless users rather than to design defects. For example, there is a small horizontal gap between the moving step and the stationary sidewall that can cause entrapment of clothing, shoes, umbrellas, etc. A high number of such accidents occur even with the recent addition of brushes along the sidewall to discourage bodily contact.

In the case of the Levytator, this gap problem would appear to be even more serious, because a straight-sided step has to bear against a curving sidewall. However, a design of step has been developed which eliminates the gap completely, by creating an overlap between the step and the sidewall. In this respect, the Levytator is safer than the standard escalator.

At the top and bottom of the standard escalator the handrail has to bend sharply in the vertical plane. In the Levytator, the polymer or other material selected, must also be able to bend more gently in the horizontal plane.

Looking ahead

Initial estimates suggest that the price of a Levytator would be comparable to that of a traditional escalator with a similar forward length. However, as all steps remain in use all of the time, a single Levytator can be used in place of two conventional designs, effectively halving the cost per usable step.

The system has been patented in the UK, Europe, China, the USA, and City University London is now seeking to take it to market, by exploring strategic partnerships with architects, property developers and manufacturers to develop the system further and install the first, full-size Levytator.  

Further information

David Chan, Director of City’s Centre for Information Leadership (consultant to the project), City University London, Northampton Square, London EC1V 0HB. Tel: +44 (0)20 7040 8438. Email: David.Chan.1@soi.city.ac.uk A video of the model and computer simulations can be seen below or on YouTube at http://bit.ly/levytator