Elevator brake

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Elevator brakes play an important role in meeting the highest safety requirements for passenger elevators .

Technical regulations

General

Elevator systems are subject to strict technical regulations, which in EC countries are based on Directive 95/16 / EC on elevators (Elevator Directive ) , and also on state laws and standards. In addition, the European standard EN 81 applies in the European Union .

In Germany , in addition to legal regulations, the Technical Rules for Elevators (TRA) and the German adoption of DIN EN 81 (→ DIN standard ) apply . In Austria , the regulations on elevator systems are a matter of the state in connection with the relevant ÖNORM EN.

EN 81

The detailed regulations for elevator brakes in elevator systems are documented in EN 81. The standard stipulates that two brakes or brake circuits that work independently of one another must be present in an elevator drive ( redundancy ). This ensures that the car is held safely even in the event of a total brake circuit failure. In the past, mainly electrohydraulic shoe brakes with two brake pads were used. These elevator brakes are still widely used today, but are no longer suitable for modern elevators without a machine room. Elevator concepts without a machine room require extremely compact and low-noise elevator brakes, as modern elevator drives are often placed in the shaft or ride along on the car.

Noise reduction

Passengers in passenger elevators find noises caused by the drive to be frightening, even if there is no cause for alarm. Therefore, elevator brakes, which are arranged in the vicinity of the car, are equipped with damping systems in order to minimize the noise when the brakes are switched. As a rule, values ​​of 60 to 65 dB (A) are aimed for. In some cases - as is usual with platform brakes - values ​​of 50 dB (A) are required.

Modern designs for elevator brakes

Today electromagnetic dual-circuit safety brakes are preferred in all common elevator concepts . Depending on the application, very different variants have established themselves on the market.

Designs

The following designs are widespread:

  • Elevator brakes in which two individual complete brakes are arranged one behind the other.
  • Versions with two or more brake circuits that act on a friction lining. The magnetic coils of the individual brake circuits can be accommodated in a common coil carrier or each in a separate coil carrier.
  • Brake calipers which are arranged on a brake disc. Redundancy is achieved by using at least two brake calipers.
  • Single-circuit retrofit brakes for attachment to the traction sheave. This allows old elevator drives that are only equipped with one brake to be upgraded to a current safety level at low cost.
  • Elevator brakes with a magnetic coil and segmented armature disk.

Function of the electromagnetic elevator brake

Electromagnetic elevator brakes work according to the fail-safe principle. They are closed when de-energized and thus also offer safety in the event of an EMERGENCY STOP or power failure. When the brake is de-energized, several helical springs press against the armature disk. The friction lining, which is connected to the motor shaft via a toothing, is clamped between the armature disk and the motor mounting surface. The shaft is braked. If the magnet coil is energized, a magnetic field builds up, which pulls the armature disk to the coil carrier and thus releases the friction lining carrier and thus also the motor shaft. The brake is released.