One of the major problems of accessibility for people with disabilities and older citizens who are restricted in their mobility is getting up and down stairs. In cities and towns with more concentrated populations, houses are generally built with two storeys or more so they can afford lots of floor space without taking up too large a footprint. This means there are stairs to negotiate and for people with restricted mobility this can be a real problem to the extent that it affects their quality of life.

So to get around the problem, back in the 1920s an engineer called C.C. Crispen invented the precursor to our modern stair chair lift. This is a device that takes a basic chair and connects it to a rail that travels the length of the stairway on which it runs on small wheels or rollers, pulled up by a chain or cable. The stairlift is operated by a sensitive lever or toggle located on the seat armrest, for which the operator can travel up or down the stairs seated in a 90 degree angle with their back to the wall for the maximum comfort.

The principal is the same now as it was back then, except we now have the benefit of better materials and more refined mechanisms with which to build them. The modern stair lift employs aluminium of steel rails, sophisticated drive mechanisms and a chair that can swivel and lock into a position facing the top of the stairs when it gets there, so the occupant can get out of it easily. Similarly when coming back down the stairs, the user simply sits on the chair, swivels and locks it back into its running position and operates the lever to go down. The swivel mechanism of the chair can be manual or motorised as the user requires.

The stair chair lift is able to run on a straight rail or a curved one to negotiate curved or corner stairways and the drive mechanism is generally very smooth and almost silent. They are a real boon to the elderly or those with disabilities who don't want to move from their home but still need to have access to the upper floors of the building, for instance if there is only one bathroom situated on the first floor, as is often the case in smaller, city homes.

Stair lifts are very robust in construction and are able to accept fairly heavy weights, which will vary from model to model, so if you are contemplating having one installed in your home, you should fist check that he model you want is able to take your weight. Presently, some of the stair lifts with a high weight capacity can carry loads of up to 21 stone. Special heavy duty stair lifts can exceed that amount, carrying up to a maximum of 28 stone, although most general stair lifts are not built to take anything like that much weight.

It's also important, should you have decided to install a stair lift in your home, to take some professional advice from a person with experience in the field. Generally, informed advice can be obtained from community occupational therapists. They can be found at the Social Services Department of your local authority.

A stair chair lift will last for many years with occasional maintenance and general looking after. This is one of those inventions that is near genius in its applications yet the very simplicity of the idea makes them such a useful addition to a home where mobility is an issue.