(Photo: © Henning GmbH & Co. KG / ChatGPT)
September 2025
Thanks to intelligent sensors and high capacity integrated computing units, overload measurement has become an important instrument for efficiency valuation and condition-based maintenance.
By Tim Ebeling
Overload measurement is an important safety function for every lift. The variations range from a simple and affordable microswitch, whose operation is relatively imprecise and frequently has to be reset, to very reliable systems that only have to be adjusted once or not at all, and reliably detect car overloading. But modern systems can now do far more than just classic overload control. They have become an important instrument for efficiency evaluation and condition-based monitoring.
This development is based on the deployment of advanced system-on-a-chip (SoC) solutions. These highly integrated modules combine computing power, periphery connections and safety features in very compact form. The sensors can be flexibly integrated in modern lift solutions or cloud-based maintenance solutions using standardised interfaces (e.g. UART, CAN 2.0, GPIOs) and wireless transmission (WLAN, Bluetooth 4.2).
Given the multitude of interfaces in particular, one is forced to think of cyber security – and these systems do indeed boast impressive features in this sphere: even simple SoCs already possess security features such as secure boot and hardware encryption, meaning "cyber"- secure operation is guaranteed.
Another protection is the activation of particular interfaces – particularly radio-based ones – by physical action. For example, if wireless network access is only provided by the push of a button and then only for a limited period, this is a further obstacle for cyber criminals.
In the case of overload measurement, the operating menu can be outsourced conveniently to the smartphone. This makes it possible to implement the digital product pass, generate reports on documentation and offer numerous special functions without the need for special apps or operating system requirements.
The computing power available can also be exploited to make effective use of the wear volume of ropes and traction sheave. The load distribution in the rope set has a very great influence on the service life of the ropes. In the authoritative standard work on wire ropes in lift building by Prof Dr Klaus Feyrer, an equation is stated with which the bending performance of wire ropes can be determined in relation to rope tension.
If all the parameters in this equation (such as the ambient conditions, mechanical rope parameters, etc.) are kept the same and only the difference in rope tension is considered, astounding effects of the load distribution on the service life of the ropes emerge.
For example, a reduction in the load difference between the load-bearing ropes by 15 percent results in an extension of the rope service life by 38 percent. Moreover, correctly adjusted ropes prevent "shrinkage" (wear) of individual traction sheave grooves. The evaluation unit provides an adjustment assistant for this purpose on the smartphone. As a result, rope adjustment becomes very straightforward and efficient even in the case of multiple suspensions since each rope is only "grasped" and tensioned once according to the guidelines of the assistant.
Apart from the pure recognition of overload situations, such systems permit consistent and differentiated consideration of the balance of forces in the car. Analysis of shaft efficiency is particularly interesting. By means of comparative load measurements during travel upwards and downwards with identical loads, determining the degree of mechanical losses and as a result of shaft efficiency in the lift system is possible. The measurement value "shaft efficiency" allows conclusions to be drawn on the quality of assembly and maintenance – and all of this without invasive procedures.
When not just the overall balance of forces but also the forces in each piece of hoisting gear is considered during travel upwards and downwards, additional very interesting results are obtainable. By means of pre-existing algorithms, the system automatically detects traction sheaves that will in future be unevenly worn and if necessary reports this to higher systems.
These expanded diagnostics also have considerable benefits for lifts without machine rooms or for retrofitting projects since they help to detect uneven rope tensions, ropes that have are twisted or defective components - long before malfunctions occur.
In addition, the systematic evaluation of time series can serve as an early indicator of wear. Through secure connection to higher systems, the measurement data obtained can become part of integrated lift monitoring and support predictive maintenance concepts.
Intelligent load measurement is more than just a safety-relevant component of overload detection – it provides essential inputs for modern control and maintenance systems and permits objective evaluation of the lift quality, both in new construction as well as in situ.
As a result, new potential opens up for manufacturers, operators and service providers, which can be used profitably.
The author is one of the two managing directors of Henning, a manufacturer of lift components and measurement technology.
More information: https://henning-gmbh.de/
Digitalpaper
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