Brake Monitoring is currently advancing in the stage technology more and more into focus. The Andes stage drives built electromagnetic braken are under scrutiny because they have to save lives in an emergency. Mayr Antriebstechnik can already provide brake systems that are optimized and equipped for targeted brake monitoring. A stage winch with multiple individual brakes secures action scenes in the blockbuster Spiderman.

Contents

• Safety brake monitoring for stage technology
  • Enlightenment work is necessary
  • Release monitoring increases safety
  • Conditioning of friction linings
  • No compromise in terms of safety
• Stage winch with six individual brakes lets Spiderman fly
  • One brake replaces the other
  • Floating storage of the brake
  • Influences on the noise behavior
    
    

Safety brake monitoring for stage technology

13.10.2014/XNUMX/XNUMX | Braking systems in stage technology are selected by the planners and installed by the system manufacturers. After the initial acceptance by the expert, however, they are often more or less forgotten. The braking systems in prospect trains, for example, have a responsible task: they have to save lives in an emergency. In the event of a power failure or an emergency stop, it is imperative that the load bar is brought to a standstill as quickly as possible before personal injury or property damage can occur. But can the built-in braking system really do this in an emergency? In this regard, is the one-year inspection by the expert sufficient or is more frequent monitoring required, targeted brake monitoring?

Enlightenment work is necessary

Contrary to the accusation that brake manufacturers give too little thought to the specific use of the brakes; that they often only provide insufficient data and operating instructions to the system manufacturers and operators, Mayr Antriebstechnik has been successfully doing here for years awareness training. The company has set itself the task of making winch drives for stage technology safe.

Devices for braking energy recuperation for electric drives

The Allgäu people are developing for this industry-specific Safety brakes and supply system manufacturers and operators with the specifically required industry-oriented data. If necessary, the engineers even develop new processes or set up new series of tests in order to provide missing data and incorporate this into the final test. The recently introduced, newly developed non-contact release monitoring using an initiator that is resistant to magnetic fields is just one example. It compensates for the well-known disadvantages of the mechanical microswitches commonly used to date in common brake systems from all manufacturers.

The manufacturer's existing braking systems can be easily mechanically combined for a comprehensive Brake Monitoring gear up. However, the brakes in stage technology do not yet receive enough attention from the control side: the control still not enough potential functions are specifically queried, monitored and documented to make the system transparent and even safer.

Release monitoring increases safety

In the Lifting axes of industrial plants the company, on the other hand, has been using appropriately equipped braking systems for a long time. Similar to stage technology, these are also about preventing personal injury and property damage in a targeted and reliable manner. So-called safety systems – a software solution tailored to the braking system – are integrated into the control systems used here. At specified intervals or before an increased safety requirement is imminent, these brakes are continuously queried for their switching function by the so-called release monitoring.

In addition to that static braking torque to be able to close, the motor runs against the closed brake with a motor current value and time window defined by the system manufacturer. If the defined motor current value is reached, the static braking torque is OK and the axis is safe. On the other hand, he can Motor If you "pull the brake" before the motor current value is reached, the axis is locked. the steering In this case, it detects an axis that is not safe. In order for the system to be released again for further processing, previously defined processes must be carried out.

The braking torque, which is the most important variable when using safety brakes, can be determined almost exactly via the motor current. There is currently no direct reading option on the braking system itself. In addition, there is already the possibility today of using the non-contact, fail-safe release monitoring, a brake system already mentioned Temperature monitoringto wear monitoring as well as the corresponding rectifier modules with optimized switching times. In this way, the brake manufacturer also creates the conditions for stage brakes to be able to integrate brake monitoring into the control in the future.

Conditioning of friction linings

Those are not to be neglected Brake pads with the possible occurring friction lining states. Because a braking system is only as good as the selected friction system with the corresponding friction lining and its current condition. A safety brake with a friction lining is currently delivered in a “green state”. Although this guarantees the minimum nominal torque, the surface cannot yet be classified as thermally stable.

One speaks of a “green state”., if the friction lining has not yet performed any friction work, i.e. has not yet been braked in or conditioned. If the friction linings are not braked after installing the travel drive, they can be destroyed during the acceptance test by the expert in the worst case. This is because the maximum load can cause the friction lining surface to be thermally overloaded. Due to the properties achieved after braking, a conditioned friction lining can absorb significantly higher friction work in the form of thermal loads without being destroyed in the process.

No compromise in terms of safety

A thermally overloaded, destroyed surface must never occur during operation. In this case, it must be assumed that the friction pairing is no longer working and therefore that the braking system is no longer working. The lining is thermally destroyed and the braking torque is at a value that can no longer be defined. A secure hold is therefore no longer guaranteed. For this reason, the conditioning process should also be part of brake monitoring in the future and integrated into the control system. This stabilizes the braking system for its long service life. The conditioning does braked friction linings with improved response and optimal operating characteristics.

However, general information on the data required for conditioning or for a refreshment process of the friction linings is not possible. Because improper use can lead to the destruction of the friction lining and consequently to a loss of braking torque. Specific data can be requested from the manufacturer. These will then be used if necessary retrievable as a data set stored in the controller. In addition, the associated installation and operating instructions are already extensive and can be called up for specific industries. Special adjustments and additions are possible at any time on request.

The basic requirement for brake monitoring in stage technology is one precise definition by the relevant responsibilities and finally the implementation by the system and control manufacturers. There are already optimized and equipped systems for targeted brake monitoring. So it is no longer a question of whether the necessary technology is available, but only whether one would like to make the additional effort for greater security and reliability. When it comes to security, however, there should be no compromises.

The author is Peter Lucke, branch manager for stage technology at Chr. Mayr GmbH + Co. KG in Mauerstetten.

Stage winch with six individual brakes lets Spiderman fly

11.07.2020/XNUMX/XNUMX | In the cinema hit Spiderman the comic hero flies in the action scenes through the New York urban canyons. So-called flying machines are used to record such scenes. Stage winches move the stuntmen through the air on thin wire ropes.

Stage winches are also used in theatres, music houses or on concert stages to move, lift and lower scenery, curtains or heavy spotlights. To protect the actors Such braking technology is equipped with redundant safety brakes from Mayr Antriebstechnik, which are specially designed for stage applications.

In addition to the Roba-stop-silenzio, the quietest stage brake on the market, the non-slip, noise-dampened caliper brakes of the series are also suitable Roba diskstop very good for stage technical applications. They can be arranged very flexibly on brake discs. The size and number of brakes determine the braking torque that can be achieved. As a rule, two brakes are used in stage winches, which work completely independently of each other. Each of the two brakes alone is capable of reliably holding the load.

This ensures that there is no danger to the players even if a brake fails. However, if both brakes are working, this concept results in one in the event of an emergency stop Doubling of the braking torque. An American manufacturer placed six individual Roba-diskstop caliper brakes on the brake disc of a stage winch. First and foremost, the large number of brakes is necessary in order to achieve the required braking torque.

One brake replaces the other

The arrangement of several brakes also has an interesting positive side effect. As with systems with two brake circuits, one brake also has the task here Failure of another brake zu compensate. An additional brake is therefore sufficient to meet the requirement for redundancy. The other five brakes together provide the required braking torque, i.e. only 20% each.

If all six brakes are intact, the system decelerates with 120% of the nominal braking torque during emergency braking. the Braking torque increase is not 100% as in systems with two brake circuits, but only 20%. The braking process is much smoother and less stressful for the peripheral components. The Roba-diskstop is closed when it is de-energized, i.e. even in the event of an emergency stop or power failure.

In the Energizing the magnetic coil an armature disk is pulled against the force of the coil springs onto the coil carrier; the brake is released. A microswitch monitors the ventilation. This can be used to prevent the drive from starting before the brake is released. The built-in hand release allows the de-energized brake to be opened mechanically for inspection or maintenance work.

Floating storage of the brake

Such modern, floating caliper brakes are state of the art today and are also widely accepted in stage technology. They are considered robust and extremely reliable. In practice, however, it has been found that slight contact between the friction linings and the rotating brake disc can cause noise. Due to the floating bearing of the brake and the magnetic effect - caused by the energized coil - the brake follows the movement of the brake disc.

This behavior leads to a slight permanent loop, which causes noises that cannot be accepted in numerous stage technology applications. Therefore, the Roba-diskstop safety brakes of the stage winch described were equipped with an exemption. It ensures that when the brake is open, the brake disc is engaged on both the left and right side even air gap is available. Even if the friction linings wear unevenly, this patented design ensures that the brake disc can rotate between the two friction linings without rubbing due to the even air gap when the brake is open.

Influences on the noise behavior

Before the "invention" of the release, attempts were made to get the problem under control by precisely setting the air gap. However, this did not work reliably. However, as already mentioned, continuous grinding can also be caused solely by the magnetic attraction between the armature disk of the brake and the brake disk. Other influencing factors are the air gap and the so-called "runout" of the brake disc. The smaller the air gap and the bigger the run, the higher the risk that the brake disc will rub and cause noise when the brake is released.

Some brake suppliers work with very small air gaps in order to keep the switching noise low. The Roba-diskstop works with a relatively large air gap and still switches extremely quiet. It is equipped with a highly effective, patented noise damping system that keeps the switching noise low even when the lining wears and the air gap increases as a result. Mayr Antriebstechnik offers a wide range of braking systems for all modern stage applications.

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