Remote-controlled overhead crane operation: Facilitating the lifting of heavy loads

Overhead travelling cranes play a critical role in a variety of industries, such as aerospace/aeronautics, automotive manufacturing, chemicals and minerals, pulp and paper, steel production, utilities, as well as in the grain industry, logging, rail yards and ship loading.

Traditionally, the industrial overhead travelling cranes have been operated by human operators in cabs inside the cranes. In such cases, the operator's actions are guided by hand signals from a person outside the crane. In the past, overhead cranes were operated by operators in the cab. The person on the ground hooked the chains, did the loading and had to wave his hands to indicate to the operator where to move the crane.

In other cases, instead of having an operator in the cab, a person outside the travelling crane would operate the unit via pendant button stations suspended from the crane.

In recent decades, technology has advanced to the point where overhead travelling cranes can be operated by remote control. Although this technology has been around since the 1960s, it has continued to improve over the years, and newer systems offer more safety, reliability, efficiency, versatility and cost savings than in the past.

The two standard technologies for remote-controlled overhead crane operation are radio frequency (RF) signals/waves and infrared light. Although both are still available, RF technology is the more popular of the two, accounting for approximately 98 per cent of the market, according to Magnetek Material Handling, due to its advantages over infrared technology.

For example, infrared units have shorter operating ranges than RF units. In addition, infrared light can be deflected by dust or other particles in the air, and even blocked by larger objects in its path.

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Infrared technology was an interesting idea. However, in most plants, especially in steel mills, there is too much dirt and dust, and all the reflectors and lenses of the travelling crane are covered with dirt and dust. As a result, you have to constantly clean the sensors and other surfaces.

Basics of industrial overhead crane remote control technology

A remote control system consists of two units. One is a portable transmitter that creates control signals. The other is a receiver that is permanently installed on the travelling crane. The receiver is connected to the crane's control unit. Each switch on the transmitter creates a specified combination of «pulses» that are transmitted to the receiver, which then decodes the «pulses» and transmits them to the crane's motor controllers.

While remote control technology for overhead cranes can be purchased already installed on new cranes, in many cases it can also be retrofitted to existing cranes. A prerequisite for retrofitting is that the existing crane must be equipped with magnetic motor controllers, rather than drum controllers (the latter are common in many older models of cab-operated cranes). Another prerequisite is that the brakes must be emergency-ready and connected to the existing motor controls. For example, hydraulic brakes that are traditionally operated by a foot pedal must be converted to allow electronic activation.

With the introduction of variable frequency drives (VFDs) a few years ago, the technology has kept up with the times. Many smaller, less expensive remote controls are two-button units that provide direction and high speed. Thus, they have always worked well for small cranes.

However, with the introduction of variable frequency drives (VFD) a few years ago, most large cranes now have five speeds: slow, slow-medium, medium, medium-high and high. This allows for greater control over the motors and speeds. With advances in technology, remote control units can also respond to the need for changes in speed.

There is a wide range of products, from the most basic to the most complex.

Economical off-the-shelf systems are available that would be suitable for applications such as jib cranes.

At the other end of the spectrum are highly complex customised solutions that require a significant amount of in-house engineering.

A custom application is appropriate any time there is a critical lift that requires a high level of control or a greater awareness of what is happening with the systems during the lift. Another situation would be when the crane has many different capabilities and requires a higher level of selection for the operator, who may need to control several different components of the crane at different times.

Benefits of remote controls for overhead cranes

One benefit of remote control operation is improved safety. That is, it is not necessary for a person to be physically close to the crane and its operation, risking being struck by the crane or its load. Nor is it necessary for there to be a human operator inside the crane cab, who could also be at risk of injury. Although an operator in a cab is less likely to be injured compared to the person outside the cab, cab operators are still prone to ergonomic injuries (neck, lower back, arm, hand, etc.) due to constant bending and manipulation of the control panel. Fatigue is also another problem for cab operators.

Safety is especially improved when switching from a pendant system to a remote control system. Smaller cranes tended to have pendants. Switching to a remote control provides more safety, as the person operating the controls can now be further away from the crane and operate it at a safer distance, rather than having to operate the pendant right next to the load.

Another benefit of remote control technology is improved efficiency, when installed on the right cranes. In other words, while there are many benefits to remote control crane technology, it is not necessary or appropriate in all situations. This depends largely on how often the crane is operated. Cranes that operate 90 or 100 percent of the time are best when operated by cab-mounted operators.

On the other hand, cranes that are only operated a couple of times a day are also likely to be better when operated by cab-mounted operators, not because of greater human efficiency, but because the limited use of the cranes probably does not justify the costs associated with the purchase and installation of remote control technology.

Cranes that operate between 20 and 80 percent of the time are the most likely candidates for remote control technology, as this is where the greatest efficiencies of the technology will be achieved. The reason: one of the people who would otherwise be involved in operating the crane, either the cab operator or the external «helper», can be assigned to do other work.

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Efficiency improves especially when moving from a cab operator arrangement to a remote control system. Radio-controlled technology allows you to give complete control to the man on the ground. This allows the company to relocate the crane operator to some other useful job. In addition, remote control units allow cranes to operate faster, which means more work can be done in less time than when the units are operated by operators in the cab.

What are companies looking for in remote control technology for overhead cranes today?

Demands continue to increase and crane manufacturers continue to respond.

One trend is the growing demand from operations managers for the field serviceability of the units, such as the ability to change spare transmitters as needed, or even replace a breaker if it is broken. «Being able to do this helps keep productivity high.»

Another trend is the demand from companies for greater reliability, both in terms of robust design and increased durability. Increasingly, operators and operations managers are demanding greater reliability, especially in terms of robust product design.

In addition, industrial companies are showing an increased interest in systems that can be connected to a hosted programmable logic controller (PLC), rather than having relay outputs. However, there is still a segment of customers who wish to continue using relay outputs, because it is easier for maintenance personnel to diagnose a standard relay system than a system that connects to a PLC.

Today, more and more customers are looking for enhanced diagnostic capabilities. One solution is the Radio Drive Serial Interface System, or RSDI system, which allows radios to talk to variable frequency drives (VFDs) via serial communications.

Serial communication technology not only provides crane control, such as commanding crane movements, but also extracts information from the drives and sends it wirelessly to a display on the transmitter.

This allows the operator or maintenance person to gather a lot of information from the crane without having to climb on the crane to access that information. One of the benefits of this is that it allows the maintenance person to determine where troubleshooting activities will begin before climbing onto the crane. This helps to reduce downtime.

As noted, while the basic technology of remote-controlled crane systems remains the same, features have continued to be added over the years. There are now remote services that connect data, equipment and people.

In addition to offering traditional features there are a number of «smart» features, each of which can be applied to old and new cranes. Features include sway control, impulse motion, microspeed, shock load prevention, slack rope prevention, hoist synchronisation, extended speed range, target positioning, end positioning, working limits and protected areas.

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Customised remote control solutions for overhead crane efficiency

From Technology for Industry, our value proposition focuses on connecting you with companies that specialise in overhead cranes and advanced remote control systems. We understand the complexities and challenges you face in your industrial operation and we are here to facilitate the integration of cutting-edge solutions that will boost your efficiency and competitiveness.

• Access to ExpertsThrough our extensive network of contacts and partners in the overhead crane industry, we provide you with direct access to specialists experienced in the design, installation and maintenance of remote control and automation systems.
• Tailor-made solutionsWe understand that every operation is unique. We will work closely with you to understand your specific requirements and then connect you with companies that can offer customised solutions that are perfectly suited to your needs.
• State-of-the-art technologyWe partner with companies that remain at the forefront of overhead crane and remote control system technology. This means you can take advantage of the latest innovations to improve productivity, safety and efficiency in your operation.
• Process OptimisationBy connecting you with experts in overhead cranes and remote control, you will be in a favourable position to optimise your lifting and transportation processes. From planning to implementation, we provide you with the support you need to achieve tangible improvements in your operations.
• Focus on ResultsOur focus is on delivering tangible results. We strive to connect you with companies that not only offer cutting-edge technology, but are also committed to customer satisfaction and successful project delivery.
• Risk ReductionBy partnering with overhead crane experts, you can reduce the risks associated with implementing new technologies and solutions. We help you identify and address potential challenges to ensure a smooth and successful transition.

We can help you achieve a strategic partnership that will connect you with the best minds in the overhead crane and remote control industry. We're here to simplify the process, provide you with expert guidance and ensure you get solutions that drive the success of your industrial operation. Ask to speak to a specialist