Stair Lift Design
Like most products, early stair lift designs were very crude, uncomfortable and not particularly safe! Oftentimes, ropes or cables were utilized to haul the seat up the staircase track and the static drive unit was positioned at the top or even underneath the staircase. Thankfully, those types of stair lift have long since passed into history, helped on their way by the invention of the mobile drive unit.
Mobile Drive Unit Stairlift
As the name suggests, this type of stair lift utilizes a drive system that travels up and down the staircase, with the seat attached to it. The carriage contains an electric motor and gearbox and all of the associated bits and pieces to control it's motion. Rope systems were replaced by either steel cables or multi-link chains, very similar to bicycle chains. The motor turns either a spool to reel-in and reel-out the cable, or a cogged wheel that climbs up and down the chain. Cable and chain drives are a whole lot better than ropes but can still be problematic and messy, as well as uncomfortable. Quite surprisingly, some manufacturers still utilize cable or chain-drive systems today, even though these devices require continual lubrication and periodic re-tensioning or replacement of the cables or chain.
Powered by Mains Supply
Typically these stair lift types are powered by the domestic electric supply. This means that the unit is permanently connected to a 110 volt AC supply. AC powered stair lifts are a little outdated, when compared with more modern equipment. Their main disadvantage is that if a power outage occurs, the stair lift will not operate, which could be a significant problem if the equipment comes to a halt in the middle of the staircase with the user aboard.
In addition, the domestic electric supply is potentially dangerous - particularly if the equipment malfunctions. Failure of the cable that supplies electrical power to the drive unit is quite common - mainly due to the continual flexing and tensioning it must endure when the stair lift is in use. AC power is rather less controllable than DC (battery) power, which makes comfort features, like a soft start and soft stop, more difficult, or often impossible to include in these stair lift types.
Latest Design Innovations
The latest design innovations have taken safety, ease of use and comfort features to an altogether higher level. Today's more modern designs use DC power - an onboard battery pack that is re-charged, using a low voltage transformer. These stair lifts remain operational in the event of an outage and present no risk from electric shock. Efficient rack and pinion drives have replaced cables and chains - being much quieter, cleaner and safer. An electronically controlled soft start and soft stop feature should be insisted upon as should an emergency brake - often called an 'over speed governor'. This device prevents an uncontrolled descent of the stair lift carriage and seat - and is a mandatory component in most countries - though strangely, not here in the US.
Today's stair lifts also have neat features like infra red remote controls, rather than hard-wired call/sends or interference sensitive radio-controlled remotes. They have seats that swivel at the top of the stairs and pressure sensitive surfaces that stop the lift if it comes into contact with anything on the staircase.
Many utilize a toggle switch or joystick control that is easier to use than fiddly buttons and some even have self-diagnostic systems that make service and troubleshooting easier for the user and the technician.
The Future of Stairlifts?
And what about the future? There will see more extensive use of lighter, more rigid construction materials, like pressure die-cast alloys and injection molded plastics. Integrated motor/gearbox systems are more efficient, more compact and less expensive to manufacture and maintain. We will see more advanced tubular aluminium rail systems that provide a more stable and smooth glide.
Like the motor industry and all electrical appliances the more advanced stairlifts will include electronic circuit boards which will control the lift making it safer and more reliable. This will enable manufacturers to include enhanced status displays, so the user of the lift will be able to understand what the lift is doing at all times - so as whether the lift is correctly parked and which safety sensor may have caused the lift to stop due to an obstruction.
Due to advances in technology and materials and the increased demand and awareness of stairlifts the future of stairlifts is looking good for the potential user. Stairlifts will be safer and more reliable, easier to use. Stairlifts will also become more commonly seen and talked about as people start to realise the benefits of having the freedom of their entire house by having a stairlift.