AUTOMATION


distance becomes small the sensors cut power to the drive motors and prevent the carriage from travelling beyond allowable limits. Contrinex is a Swiss-based global


technology leader for smart sensors for complex automations. They produce sensors of all kinds, including those for harsh operating conditions. One automated container port that consulted them was experiencing problems. Mechanical play in the drive system of the crane carriages were resulting in the carriage drifting as it travelled along the crane structure. The sensor devices that were originally fitted had a sensing range of 15mm, but this was proving inadequate. Occasional collisions occurred with the crane structure, causing damage and interrupting operation. Replacement sensors with increased sensing range were needed. Inductive sensors from the Contrinex Basic range were substituted. Many sensing devices now are plug-and-play (PNP), making such substitutions simple. Industry standard housings (40x40mm polyamide glass fibre housings in this case) make them drop-in replacements for the original devices so little downtime was incurred during the changeover to the new sensing arrangements. The inductive sensors devices have a 20mm sensing distance that eliminated the risk of collisions. They are available as IP68 or IP69K rated units and are ideal for the outdoor working environment of a seaport.


Communication with the crane’s control


system is via a PNP changeover interface, replacing the existing two-wire arrangement; a flexible PUR-sheathed cable provides the electrical connection. A step improvement in operational performance was evident immediately after the new units were installed. The new sensors provide reliable sensing of each hoist’s position with no reported collisions since the date of installation. The customer has reported a marked reduction in crane downtime with an associated decrease in expenditure.


Kill switch engaged


Redundancy is just as necessary in safety related applications such as AI-controlled hoists as it is in nuclear technologies. A single sensor, or just a single technology,


is frequently not enough. Even in non-safety related cases, maximum operational reliability is essential. One solution, from Czech sensor- manufacturers Sick, is based on a safety controller that runs cyclical tests to check sensor detection behaviour, sensor response to entry commands and checks also that output signals are switching correctly. Detection of obstacles – sometimes


unexpected ones – along the path of industrial cranes is another essential safety feature. Here, too, Sick have suitable sensors. Their AOS104 RTG and AOS504 RMG object detection systems monitor for objects such as twist locks – for container cranes and terminals – or


A variety of sensors can be used, from lidar to inductive sensors. 28 | August 2025 | www.hoistmagazine.com


service vehicles, and are said to do so reliably and with no blind zones. The AOS in the name stands for Advanced Object Detection System, and is a lidar device. lidar works on the same principle as radar – both are time-of-flight methods for measuring distances. But rather than sending out radio signals, listening for the reflected echo and timing it as radar does, lidar uses laser beams that reflect off the distant object. It measures the time of return and, from that, multiplying it by the speed of light, works out the distance. Telemecanique is a French company that offers over many types of sensors including limit switches, pressure sensors, photoelectric sensors and proximity sensors. On an overhead gantry crane, all of these might be used. Controlling the stop and slow down of the horizontal movement can be done by a single two-way two-speed limit switch. Photoelectric sensors can produce long distance detection for anti-collision functions, and for detecting another crane or another girder on the same runway. But not all sensors have to be digital. Limit switches are an example – a simple rocker arm, that is moved by physical contact with an end-stop, can be just as effective, more robust and much more intuitively understandable. Synchronisation of multiple trolleys, girders and hoists on a single runway is another prime example of where automation can improve safety. It need no longer depend on the skills and close attention of sharp-eyed operators. Tandem function sensors ensure that the two overhead cranes constantly detect each other’s relative position and adjust their movements accordingly. Again time- of-flight based sensors are a solution. Some such sensors contain tandem function and anti-collision functions built in; others require configuration through a PLC (Programmable Logic Controller) for example. Thus, another specialist in this sector, Sensor Partners, headquartered in the Netherlands, in the first category have their LAM 5.21. It has a switching frequency of 100Hz, a sensing range of 70m and an accuracy of plus or minus 30mm. They have a wider choice in the second category, with sensing ranges of up to 270m and accuracies down to plus or minus 3mm. Doubtless automation will increase, even among smaller capacity hoists. It is also clear that the legalities surrounding it will gradually become clearer. It is a brave new world that we are looking at – at least, let us hope so. Some fear instead that AI will lead to a dystopian machine-controlled nightmare in which humans are irrelevant at best and eliminated at worst. To prevent it, remember to install that kill switch.


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