Load monitoring can be divided into two main areas: overload protection and remote monitoring. Almost every crane is equipped with one (if not two) systems that can be used to improve safety and productivity. Simon Hastellow reports.

The most direct form of load monitoring is overload protection. Simply put, a 5t hoist will be equipped with a 5t overload device, no matter what the operator does, the hoist will not run under a load of 5t or more. As standard, all new cranes will be equipped with overload devices related to their lifting capacity. There may still be some older cranes still operating without them, but the company can easily retrofit suitable devices to existing equipment.

The overload protection device is installed on the wire rope on the drum side and set to the relevant lifting limit value. It does not monitor any other characteristics of the elevator, such as whether the load is balanced, it just measures the load on the hook. However, some overload protection devices can adjust the load limit and set it to be slightly higher than the actual lifting capacity to accommodate the situation where the swing load may give false readings.

"We call this hoist overload protection, which has become an area of ​​growth. The most basic is the overload device that prevents the hoist from exceeding the preset limits of any crane or crane. Health and safety regulations in the UK and Ireland are always more To understand cranes and overload equipment, H&S is also increasingly asking about overload protection. This is purely for safety reasons,” said Patrick Doyle, managing director of WH Scott & Son.

"Overload protection devices can be mechanical or electrical. They can also be very basic and can be installed in about an hour, or they can be very complex, providing accurate readings and recording other parameters, such as the life cycle of a crane. . We recently installed an electrical system in the waste treatment plant that is connected to the PCB board in the weighing room. So every time they lift a load, it will record it in their computer system."

Manufacturing companies, such as steel plants that operate furnaces and the aviation and automotive industries, prefer load monitoring systems with very accurate visual displays and recording of lift and load weight. In these facilities, systems that require operators to respond immediately to overload conditions can also be associated with alarms and flashing lights, if the attempted elevator is too heavy.

In order to avoid safety-critical installations, it may only be necessary to have a simple LED reading system on the crane itself, which shows the weight of the load when the crane is lifted or picked up. These can usually still record data for later use or analysis, but they are simpler solutions.

"This is a very good area of ​​development, especially in the production area. Operators need to know the weight before starting to lift, so they may have overload equipment and screen monitoring," Doyle added.

Doyle said: “We recently completed an installation for Shay Murtagh, a precast concrete expert in Ireland, where it required lifting and rotating a large number of concrete molds.

The company used two 100-ton bridge cranes and needed to lift a 196-ton mold, which is obviously the limit that can be carried out safely. The operator needs to know the exact load of each crane before and during the lifting process, so we installed a display on both cranes. Once they start to lift, they can see the load of each crane. If one crane seems to be carrying more load, it can be relaxed, while the other can be lifted slightly so that the mold is stable In the state, the lift is perfectly balanced between the two cranes.

“It’s unusual to see a company combining a remote load monitoring system with an in-cab display. For any product in the 1-ton to 5-ton capacity range, the cost is approximately £2,000; compared to the costs involved, the return is Limited. Once you enter the 10t, 20t, 50t or 100t range, the additional cost becomes irrelevant. They may have spent more than £200,000, so the additional cost of the load monitoring system is negligible. We are now creating Every crane offer includes a load monitoring option and advertises the benefits of these facilities to customers,” concludes Doyle.

Remote monitoring of elevators has become the de facto standard in many industries. It not only further improves safety and productivity, and maximizes the use of each elevator, but also further records and monitors the life cycle of the crane, including the operating time that may affect the maintenance plan.

"Now more and more customers not only want to view the load, but also want to record and remotely access it from time to time. We can adapt to this through our TW-3.0-T handheld display record, and then customize to include other modules, These modules allow remote viewing access from anywhere in the world through a web portal," said Martin Halford, Managing Director of DLM UK.

"We have the telemetry tensile load chain TL-3.0 and the telemetry shackle load cell TS-3.0, which can be used to measure the tensile load on the gantry and bridge cranes. These can be used under the hooks to measure on the gantry cranes. Load.

"DLM’s wireless running line monitor is used for crane winch lines, sitting on the winch line in situ and measuring the line tension. In both cases, the DLM device can be transmitted back to the TW-3.0-TS display, which can pass RS232 port or any analog output port that can be input into the crane control system for output.

In this way, the load can be monitored and the crane can be operated safely, indicating and preventing overload conditions.

"Our new TW-3.0 product series is currently the most advanced handheld display on the market. It can be paired with any of our wireless load cells marked with the d+ logo. This range allows 800m wireless range with frequency hopping protocol, making it suitable for High noise environment and very reliable. It also has a built-in alarm function, overload count, USB data recording time when the micro USB is inserted into the base, the ability to communicate with 12 load cells, and our math channel, RS232 and analog forwarding.

"The latest development of this product series will be the USB dongle, which can be plugged into a laptop or PC to directly receive the load cell signal, and then display the load value on the software developed by the selected DLM. With the built-in Bluetooth module, it will take further Developed to connect to smartphones.

"The display can be paired with a load cell, so multiple people in different locations can read or record load readings, or connect a handheld display to a PC. We have also developed a custom load monitoring system that enables users in remote locations to use the Web The portal dials into the system to access real-time information about what happened on the crane, as well as access to stored data logs.” Halford concluded.

JCM Load Monitoring in Aberdeen is equipped with various radio load links, shackles and weighing systems. The company supplies new products globally, mainly for the petroleum and offshore sectors, and pays more attention to leasing and serving more local companies serving offshore businesses in Scotland.

"We upgraded the radio package with the ALRS2 system, which brings new features to the market and enables operators to obtain more reliable measurements," said Yvonne Stewart, general manager of JCM Load Monitoring. "ALRS2 has a large, easy-to-view display that can continuously display actual load and peak load."

If required, JCM can also provide a fixed monitoring system for the bridge crane, connected to its ALRS2 handheld monitoring unit or via a data link to a PC. "We are constantly identifying new applications and finding solutions for customers," Stewart concluded.

Digital methods have also been applied to load chain links—both with holes for shackles at the top and bottom, usually between the hook and the load—though traditional systems are still in use. "The internal strain gauge responds to the strain on the housing and sends a signal to the reading instrument through a wired or wireless link to determine how large the load is. We can make them into a capacity of 500 tons or more. They have very good accuracy. It’s within 0.15%. They are made of aluminum and are lightweight,” said Marie Samuelsson, CEO of Gigasense, which produces load links as part of its product portfolio. Lifting a few tons and saving a few kilograms may seem trivial; but as she said, “If you lift several times a day, even 30 kilograms, it will add a considerable load to the total weight of the day.

"Our version of the wireless link is sent over the radio at 2.4 GHz. Wired links are used less and less; it seems that the company no longer thinks about it or is aware of it, but the technology is still good and tested and tested, and it It still works for many applications. So we also make wired links."

The same refreshing attitude towards the still valid pre-digital technology is evident in another Gigasense product, which may now be unique. “Where cargo such as ports, wharves, rail freight and container terminals are transferred from one mode of transportation to another, it is always necessary to weigh the loaded goods," Samuelson said.

Crane scales are used to do this. Most are digital, and Gigasense has indeed made digital crane scales in the past. "But we have stopped using them now, because China can make any digital product much cheaper. But we still make mechanical analog crane scales." She said that the demand for them still exists. It is small and may be a niche market; Samuelsson estimates it has a market share of about 1%.

"But people still buy some every year; and China still cannot match the robustness and robustness of the mechanical version."

Likewise, they are installed between the hook and the load. The reading is analog, not digital: the pointer points to the number on the circular scale. They work through the deformation of spring washers. Conical spring washers, also called Belleville washers, are a design known to engineers that are durable and almost wear-free during operation.

"They have a life span of millions of cycles," Samuelsson said. "The complete product is pressure-tight and meets the IP 67 standard, so there will be no water or dust inside the housing." The product can withstand harsh conditions, shocks and fast unloading. For example, it is particularly useful in destructive testing applications. Because in the case of sudden deceleration, the needle is still pointing to the continuous maximum load.

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