A triad for sustainability

Sustainability is multifaceted. The triad of quality, wear reserve and wear plays an important role (not just) in the case of lifts and components.

By Jan König and Ulrich Nees

Does the wear reserve of a lift or component affect its energy efficiency and sustainability? Of course. This is because sustainability involves far more than energy efficiency (which we dealt with in the first article of this series). The service life depends to a decisive extent on the quality, wear reserve and actual wear. Consequently, these aspects have a great influence on sustainability.

Diagram 1: Energy requirements. Photo: © Ulrich Nees

Why? If you make use of low quality lifts and components, you have to expect increased wear. This results in higher energy requirements (Diagram 1) and a shorter service life (with the associated downtimes and costs). And in this way, you do sustainability a disservice. Why? Well, the properties of worn-out products change and normally not for the better. This is due to the wear altering the component geometry, which directly affects their energy efficiency.

The wear can be very easily detected by measuring the energy requirements, which unfortunately is often forgotten. If the energy requirements of a lift continuously increase from trip to trip (see Diagram 1), you can assume it is no longer energy efficient in operation.

Causes of wear

Diagram 2: Changes in PWM. Photo: © Ulrich Nees

Let’s look at this in detail: we distinguish between mechanical wear and the wear of electrical devices. First, the mechanical wear.

There are four different types of mechanical wear:
• adhesive wear due to deficient lubrication,
• abrasive wear due to surface asperities,
• surface destruction through alternating or dynamic loading and
• tribooxidation, i.e. the formation of intermediate layers, for example, through oxide layers.

The wear of electrical components is caused, among other things, by natural aging and the loading of the components, for example by
• inadequate cooling,
• insufficient power,
• change in the pulse width modulation (PWM),
• vibrations.

Now for the practical side

Diagram 3: Oscillation speed. Photo: © Ulrich Nees

Let’s begin with an example of mechanical wear. If the maintenance company for example fails to make the prescribed oil change for the transmission, there is increased adhesive wear of the components involved. This logically leads to the service life of the transmission being shortened. To prevent this, not only does the technical documentation of the manufacturer have to be available, but also observed. Consequently, quality is also an important factor in sustainability.

Or let us consider uncontrolled changes in pulse width modulation (Diagram 2), which among other things can arise due to incorrect setting of the system, as an example for electrical component wear. This triggers a kind of domino effect: it results in increased oscillation speed of the motor (Diagram 3) and thereby unavoidably to major air- and structure-borne noise emissions, which above all means greatly increased wear of the components directly or indirectly affected. This has the familiar negative consequences for the overall sustainability.

The conclusion remains the point made in the first article of this series: sustainability involves a lot more than energy efficiency. If lifts and components are of high quality, have a high wear reserve and have undergone little wear, they are more sustainable and in the long term incidentally also cheaper.

Jan König is the owner of the engineering firm (VDI) Ing4Lifts.
Ulrich Nees is the owner of "Aufzug-Systeme + Beratung Ulrich Nees"

More informations: ing4lifts.de
aufzugsystemeberatung.de