Safety is the highest priority

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Demag double chain hoists with tandem control
New concept for suspended loads in production
Lifting solution for all industries

Together with Terex Material Handling and with input provided by the industrial employers’ mutual insurance association, the hot-galvanising company Helling & Neuhaus has developed a solution that allows workers to remain beneath suspended loads. The lifting and drop sections on two conveyor lines are each equipped with two Demag double chain hoists that are connected to each other by means of a tandem control system. According to the manufacturer, this concept, which satisfies the requirements of BGV D8 Plus hoists in full, is a pioneering solution that is suitable for other sectors of industry and provides for maximum safety.

In many production facilities it is necessary for people to spend time beneath suspended loads which are held by chain hoists. Applications such as these are subject to special safety requirements, which are laid down in the BGV D8 safety regulations.

The applications for which these design and safety requirements have to be met also include production facilities for the treatment of metal surfaces, such as galvanising plants. Even though the production process is performed automatically in most cases, the material to be coated is often attached to the spreaders and removed at the end of the circuit by hand.

Safe and reliable solution for D8 Plus hoists to meet risk assessment requirements
Helling & Neuhaus GmbH, based in Gütersloh, Germany, and part of the Seppeler Group, operates two parallel production circuits. The lifting motions at each of the pick-up and deposit stations were previously provided by chain hoists fitted with a catch. This solution operated to the customer’s complete satisfaction, however, the safety features needed to be further optimised.

Michael Rother, Engineering Director, states: “Together with Terex Material Handling and the industrial employers’ mutual insurance association, we first carried out a risk assessment and analysis. On the basis of the results, a concept was developed to satisfy the requirements of the BGV 8+ regulations and allow people to work beneath the trolleys.”

The solution employed by the galvanising specialists utilises Demag LDC-D size 10 double chain hoists, which are paired to each other by a tandem control system. Developed for transporting long materials and for spreader operation, the LDC-D has two mechanically synchronised chain lead-offs which are rigidly connected to each other by a common frame. The LDC-D unit drives a separate lifting block that has its own chain drive via a connecting shaft.

Due to high load-dependent lifting speeds of up to 24 m/min, LDC-D units are also designed for high handling rates. In addition, they provide for a longer chain service life as a result of the reduced polygon effect, since there are no additional chain return sprockets.

High safety and reliability for lifting and lowering
The four attachment and removal stations employed at Helling & Neuhaus consist of six metre-long I-beam sections, which are integrated into the conveyor track. They are held by two stationary LDC-D double chain hoists that have a hook centre distance of 800 mm. When a spreader trolley reaches one of the stations, the spreader is first locked in position and then the rail section is lowered to allow the parts to be attached for the galvanising process.

Two chain lead-offs also double the level of safety. Synchronised operation of the hoists is also monitored by the tandem control system. This arrangement ensures that the four hooks are always level with each other during lifting and lowering motions. Even if one of the chains were to break, the load bar would remain in a stable position.

The lifting and lowering stations operate with several secondary safety features – also thanks to a double brake system – to ensure the highest possible safety and reliability for the workers.

Intelligent control system integration
The tandem controls of each spreader trolley are integrated into the control concept of the material flow system. The hook position of the chain hoists is reported to the control system by additional limit switches. This system has enabled Helling & Neuhaus to achieve a safe and efficient method to implement a D8 Plus hoist unit that meets the provisions of the BGV D8 regulations and permits staff to work beneath the drop sections of the monorail circuits. The technical solution is based on the use of Demag standard components from the modular construction kit which also meet the design specifications of galvanising applications with additional corrosion protection measures.

Implemented in a minimum of time
After the project engineering work had been completed for the technical solution, the next challenge was posed by technical implementation. To ensure maximum reliability within the operating process, a test system was first set up under actual ambient conditions. Following completion of the test phase, Demag Service then successively converted the lifting and drop sections on non-working weekends.

For Terex Material Handling, this solution featuring Demag double chain hoists connected by a tandem control system serves as a prototype. The conveying and lifting equipment that satisfies the BGV D8 Plus requirements is not only of interest for companies in the surface finishing sector, but is also ideally suited for applications in other industries.

The safety concept realised at Helling & Neuhaus permits workers to remain beneath suspended loads. The solution features two Demag double chain hoists that are connected to each other via a tandem control system.

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