Industrial platforms on the move

The company

The Grand Duchy of Luxembourg has a 630-km rail network. 38 locomotives and 63 electric railcars are used to transport 13.9 million passengers annually. The Société Nationale des Chemins de Fer Luxembourgeois (CFL) is responsible for the reliable operation of the rail network for Luxembourg residents and countless commuters. It is also responsible for the repair and maintenance of multiple units and railcars, which travel more than 300 million km per year.

Kreitzler Industriebühnen GmbH, headquartered in Witten, Germany, specialises in custom-built industrial platforms, lifting platforms and special structures. The concept is based on the 100% independent production of the special structures. For inspection and maintenance on locomotives, Kreitzler manufactures equipment such as self-propelled scissor lifts as washing systems and articulated telescopic platforms for overhead line construction. The company offers assembly and other services as well as the rental of scissor and articulated telescopic platforms.

Requirement

Maintenance and repair work on locomotives, electric multiple units and electric railcars is carried out at the main CFL plant in Luxembourg City. The central workshop with a 1,000 m maintenance track is located in the immediate vicinity of the main train station. The Centre de Réparation Rapide maintenance sheds are directly connected to the rail network. There, the railcars are inspected and maintained as quickly as possible. Maintenance work is performed around the clock, across three shifts. Maintenance can be carried out on any part of the railcar, but usually involves maintenance of the doors, work on the roof, including the pantograph, or work on the air conditioning module. Demag suspension cranes are available for use if the entire air-conditioning unit needs replacing.

Smaller jobs are mostly done by employees from an aging maintenance platform. However, this now travels too slowly and is no longer fully compatible with the new generation of railcars.

Charel Weiwertz (Project Manager for new construction projects related to trains and service) therefore outlined the requirements for a new generation of aerial work platforms and CFL's specific requirements:

• Integration into CFL's existing security concept
• Reliability in multi-shift operation
• Maximum possible travel and lifting speeds
• Extension unit in highest lifting position
• Easy service access

Solution

Four aerial work platforms have been specially manufactured for CFL’s needs and equipped with maintenance features. Kreitzler employees worked on a solution that was fast, safe and reliable. Each of the work platforms can carry loads weighing up to 500 kg. This means, for example, that three people can work on each platform along with a payload of up to 260 kg, including tools or railcar components. The balanced combination of speed for the required payload provides CFL with the desired solution for working on railcar exteriors. In order to move the aerial work platforms along the railcars at the desired speed, Kreitzler soon opted for Demag modular drives. The reliable Demag components are ideal for moving the heavy work platforms and efficiently supporting CFL employees. Each work platform is equipped with two Demag offset geared brake motors and four Demag travel wheels. These are connected in pairs via a hollow shaft with involute spines.

Ready for installation and made to measure – the Demag LRS travel wheel system

The Hydropur version of the LRS travel wheels was selected for the project. Thanks to their rubber-like surface, the work platforms can move directly along the shed floor and leave no residue. In the selected size 350, the LRS can accommodate a wheel load of up to 3,000 kg and are very smooth running, even at high acceleration. The weight distribution across the wide wheel contact surface provides the work platforms with stable travel characteristics.

The perfect combination of proven components – Demag geared motors

Kreitzler chose the powerful Demag ADK50DD offset geared brake motors with ZBA90 motors from the wide range of gearbox sizes and travel motors. With motor speeds of 14,000 rpm and an output of 1,100 kW, the ZBA motors accelerate the aerial work platforms to up to 67 m/min. The positioning speed, meanwhile, is 3 m/min, which allows maintenance personnel to move the platform precisely into position. The platforms have a braking torque of 3.3 Nm. The flat design of the geared brake motors enables space-saving use between the travel wheels and a compact design for the narrow Kreitzler platforms. This creates a corridor between the two maintenance platforms in the centre aisle and at each of the outer platforms to store materials required for maintenance, e.g. oil drums.

Protected from external influences and with class IP 54 protection, the geared motors are designed to perform their work absolutely reliably for up to 16 hours a day. This corresponds to FEM classification 1Bm (M3-ISO) and a duty cycle (drive/8h) of 6.25%.

One of CFL’s most important requirements for Kreitzler was to integrate the work platforms into the existing safety concept. This is necessary to allow the industrial platform to be extended to the highest position. Electric multiple units and railcars travel along an overhead line into the maintenance shed. The voltage in the overhead line can be life-threatening, so work is only carried out when the overhead line is switched off. The process of raising the aerial work platform in the vicinity of this overhead line must be protected accordingly.

CFL has developed a safety concept for the maintenance crew by which the overhead line is disconnected and retracted as soon as the railcar has moved into position. Specific areas can only be approached with a safety key, so that disconnection is always guaranteed and the shutdown of the overhead line is checked. This is integrated into the electronics of the work platform so that you can only move to the next zone with the safety key inserted in the platform controls.

Great drive power combined with maximum functionality – Demag Dedrive Compact STO

The application module for CFL has been supplemented by Kreitzler and Demag with a Dedrive Compact STO DIC-4-014 frequency inverter, which is integrated into the Kreitzler control unit and serves as an interface between Demag components and system partner electronics. The inverter series is designed for start and stop applications. The high overload capacity and easy operation make Dedrive Compact STO another reliable component in the drive concept for CFL work platforms.

Three questions for Martin Hämmerling, Sales Engineer responsible for the project with Kreitzler Industriebühnen GmbH and Chemins de Fer Luxembourgeois (CFL)   

Demag: What were the first requirements you received from the project partner?

Martin Hämmerling: To start with, I received the technical data from project partner Kreitzler Industriebühnen GmbH. For CFL's on-site requirements, I received information about the weight of the platform, the load and the desired travel speeds. In addition, Kreitzler had already specified how the wheel blocks and drives should be arranged. The most important note related to the wheel guidance: the platform needs to move across the concrete floor of the shed. 
With this data, I was able to start determining the right components for this application. It was important to select the right wheel type, wheel size and drive power for the ratio of platform weight and desired speed. 

Demag: What product features are particularly noteworthy in the drive solution for the industrial platforms?

Martin Hämmerling: Due to the special characteristics of driving on concrete floors, the wheels needed to be selected with particular care. The choice fell on flangeless travel wheels with Hydropur tyres, which, as they have a wide weight distribution, will not damage the concrete floor. The LRS 350 size was selected for this application. The combination of Hydropur tyres, geared motor and travel wheel size offers optimum properties for the highly dynamic application of the continuously variable industrial platforms and ensures low running noise and the desired travel speeds of up to 67 m/min and a fine positioning speed of just 3 m/min.

Demag: Did this project involve any unusual requirements? 

Martin Hämmerling: The choice of a travel wheel with Hydropur tyre was rather unusual, as it did away with the standard option of guiding the wheel blocks, for example by flanges. There is simply no rail on the shed floor. For this reason, project partner Kreitzler implemented the track guidance at platform height, so that the industrial platform is guided along the entire length of the shed along the track. A further adaptation to the conditions in the CFL work shed.

Special features

The Demag LRS travel wheel system can be fitted to suit different drive tasks. With wheel loads of up to 6.5 t and travel speeds of up to 240 m/min, the travel wheels are ideal for OEMs for feeding, moving, distributing, assembling or transporting processes, as with aerial work platforms. The five connection surfaces allow for a wide range of attachment options.

In combination with the Demag offset geared motor, the CFL aerial work platforms travel with a high ground clearance thanks to their compact design. The flangeless travel wheels with Hydropur tires ensure smooth travel characteristics, even at high acceleration, and protect the shed floor.

Demag double-girder cranes with different load capacities support the maintenance of locomotives and electric railcars in the neighbouring sheds. The cranes can lift and transport complete chassis to remove individual components for maintenance purposes. CFL maintains and repairs the individual components such as bogies and air conditioning units. These are repaired and stored after disassembly so that the components are available for another locomotive or for electric railcars at the next opportunity.