How does a Platform Lift work?
Have you ever wondered what makes a platform lift go up and down? It's actually not as simple as you may think, as there are three main types of platform lift drive systems, each having their own advantages and disadvantages.
Most modern platform lifts are controlled with electrical inputs from the call buttons. These send signals to a central processor unit which initiate motors or pumps as required.
Screw and nut drive system
The first drive system we'll look at is the screw and nut system. This works by utilising a steel screw pole which runs the full length of the shaft. A drive nut on the screw is attached to a motor on the platform. The motor turns the nut and depending on the direction of rotation the lift will go either up or down.
The installation of this system often requires a supporting wall especially on longer travel lifts in order to stabilise the unit. This system requires routine lubrication of the thread, often done by a self lubricating system. The disadvantages of this system are the wear and tear on the thread of the screw and drive nut. It is usually only possible to glaze three sides of the lift shaft due to one wall being used to conceal the screw thread.
Hydraulic drive system
The next drive system to look at is the hydraulic drive system. In this system, the lift platform is attached to a hydraulic ram. To move the lift, hydraulic fluid is pushed via a pump from a central reservoir into the ram. The ram extends and the lift rises, to lower the lift, the flow is reversed.
The disadvantages of this system are that there is an additional space requirement for a pump and reservoir unit, and also that hydraulic fluid can sometimes give off an odour in hot weather.
Encapsulated chain drive system
The final form of drive system we'll look at is the encapsulated drive system. The key part of this system is the chain which is encased in a highly durable polyurethane plastic casing which guides the chain and ensures that slippage is virtually impossible.
A motor and gearbox at top of the shaft turns a driveshaft that the chains are attached to. The chains are attached to either side of the platform. As the driveshaft rotates the chains are either pulled or pushed and hence the platform moves upwards or downwards. The advantage of this system is that its durability allows the lift installer to offer a much longer guarantee on the drive system. It's also possible to glaze all 4 sides of shaft as chains run in the corners of the shaft.
About the author
This article was written by Craig Merry, Director at Invalifts. Invalifts specialise in platform lifts for homes and offices. For further information on their product range, please visit www.invalifts.com or for enquiries and advice, you can call them on 0845 468 2543.