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world of industries 1/2017 (EN)

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world of industries 1/2017 (EN)

A secure hold even when

A secure hold even when storms are raging The word standstill is unknown for the large container harbors of the world. Every day outdoor safety brakes prove their worth here, in the travel and hoist drives of harbor crane systems around the globe. They have been especially designed to resist the extreme ambient conditions of the maritime climate and to cope with emergency braking procedures with peak loads and high friction work. There is always a rush of activity at the entrance to Singapore Harbor. Hundreds of ships stand daily in front of the harbor basin, waiting to be let in. Here, in the second-largest container harbor in the world, over 30 million standard container units (TEUs) were handled in the year 2015. The loading and unloading of the ships generally takes place mostly land-side via harbor crane systems, so-called container gantry cranes, with load capacities of up to several hundred tons. In order to cope with the uninterrupted handling of sea-borne goods, all components in these systems must function particularly efficiently and reliably. Renowned manufacturers therefore place their trust in the robust and highperformance Roba-stop-S safety brakes (Image) by mayr power transmission/Germany for their travel and hoist drives. These brakes have been especially developed for outdoor applications with extreme ambient conditions, and convince customers through their simple assembly and handling as well as long maintenance intervals. Safety thanks to fail-safe principle The brakes in the travel and hoist drives of harbor crane systems fulfil two functions: On the one hand, they function in normal operation as holding brakes. This means they have to hold the system safely in the approached position once the drives have been switched off – even in wind and storm. On the other hand, in critical operating situations, during emergency stops or power failure, the Roba-stop-S safety brakes are dimensioned to adsorb peak loads with extremely high friction work. This is for example the case when loads moved downwards by hoist drives have to be braked whilst moving at full speed. CEMAT SOUTHEAST ASIA

CRANES & HOISTS Image: All function parts of the safety brakes are dimensioned so that they are also suitable for emergency braking procedures with high levels of friction work The Roba-stop-S safety brakes are electromagnetic safety brakes. They work according to the fail-safe principle, which means they are fail-safe. They are closed in de-energized condition, meaning also in case of a power failure or emergency stop. In this condition, the screw springs press against the armature disk. The friction linings of the rotor, which is connected with the drive shaft via a toothed hub, are clamped between the armature disk and the mounting surface of the brake. When the power is switched on, a magnetic field is built up in the brakes. In this way, the armature disk is pulled against the spring pressure towards the coil carrier. The rotor with the friction linings is free and the brake is released. Even in adverse conditions and during operational malfunctions, the braking effect is always ensured: Even if the brake is damaged, caused for example through cable breakage or failure of the magnetic coil, the braking torque is retained. Protected against wind and weather When loading and unloading ships, harbor crane systems must be able to provide high performance around the clock. The prerequisite for this is high operational safety with minimum standstill times for maintenance and repair work. In addition, extreme ambient conditions such as the salty environment, varying air humidity values, wind and storm have to be weathered. All components, and in particular safety-relevant ones such as brakes, therefore have to be robust and resistant. Only sealed brakes with high-quality corrosion protection can survive here long-term without incurring damage. With the Roba-stop-S, the manufacturer has developed a safety brake especially for critical ambient conditions and outdoor applications. It accords with Protection IP 67 and is therefore completely dust-tight and waterproof. The compact and solid housing with an integrated terminal box and without any pockets and grooves makes the brake resistant to damage caused by external influences. In addition, the high-quality primer on the brake body, the chrome or nickel coating of the inner components or the manufacture in rustproof stainless steel provide permanent protection against corrosion. A microswitch for release monitoring is integrated into the terminal box and thus optimally pro- About Mayr Power Transmission Mayr Power Transmission is one of the most traditional and yet one of the most innovative German companies in the field of power transmission. Mayr specializes in torque limiters, shaft couplings and safety brakes as well as electro magnetic clutches and brakes. The company employs approximately 1,000 employees worldwide and continues to grow. Headquartered in Mauerstetten, Germany the company has production sites in China and Poland. 8 subsidiaries in Germany and 7 international offices including in China, France, Italy, Great Britan, Singapore, USA and Switzerland. After several extensions to the production and administration areas in the preceding years, the company now has a 17,700 m² production facility in Mauerstetten, Germany. tected, which guarantees that the motor only starts up when the brake is released. This terminal box also features sufficient space to hold a rectifier for the brake’s magnetic coil. In addition, a further microswitch can be integrated which inspects the wear on the friction linings. On the safety brake, it is possible to mount a speedometer on the brake body. If no speedometer is used, the coil carrier is sealed with a cover. In addition, the brake has an emergency hand release, using which it can be mechanically released via two screws. If the brake is used at temperatures below zero degrees, Celsius, or in high air humidity, an anti-condensation heating system is recommended. This heating system prevents condensation from forming within the brake interior. Minimum maintenance effort required In particular in difficult installation positions, criteria such as simple installation and handling and long maintenance intervals are particularly important. Through their compact construction and small outer diameter, the safety brakes are easy to handle and can be quickly and easily installed. The high-quality friction material of the brake linings with high wear resistance also substantially reduces the number of inspections necessary, and therefore the failure times. If the friction linings wear down, the maintenance effort is minimal: Only the air gap has to be readjusted or, at the end of its service lifetime, the rotor has to be replaced along with the friction linings. A threaded bore which is tightly sealed during operation permits quick inspection of the air gap without having to de-install the brake. This low maintenance effort and the high operating safety avoid expensive downtimes on harbor crane systems and substantially reduce operating costs. Photographs: Mayr Power Transmission, shutterstock/Prasit Rodphan WORLD OF INDUSTRIES 27