How Do Safety Brakes Protect Personnel in the Event of a Pressure Drop?

Jul 05, 2018

 



Safety brakes are used to protect personnel and prevent accidents from load-bearing machine-part failures due to a leak or breakdown of a pneumatic pressure system. They immediately activate when the pressure drops. Then they exert the load onto the rod by clamping closed in a self-reinforcing function. They catch falling masses infinitely variable at any position of the stroke.

In case of an overload, the rod is subjected to a controlled slip at a high level of force. This reduces the levels of kinetic energy of the moving masses by friction. This feature allows the safety brake to be used in emergency cases to catch falling loads with well-defined braking forces.

Safety Brakes for Static Holding

Safety brakes are used as mechanical restraints for static loads. They are certified to the testing principle GS-HSM-02 of the DGUV. DGUV is the testing and certification body of the statutory accident insurance and prevention institution in Germany.

Safety Brakes for Emergency Braking

Safety brakes are used for emergency braking of loads in the load direction. The braking force is higher in this direction than the admissible load, but limited to ensure that the energy is absorbed in a defined manner.

Spring Base Design Principle

Safety Brakes can only be released if their clamping system is not under load due to their self-intensifying design principle. If the load overshoots after switching off the pressure, or moves slightly downward, then the safety brake is subjected to a partial load. The load must be raised before the safety brake is opened and before a movement in load direction is possible.

This effect can be avoided by bolting the safety brake on top of the spring-base, which provides the following advantages:

  • Raising the load before any lowering movement is no longer required, even if a small leak occurs at the lifting actuators.
  • The safety criterion “Safety brakes can only be released if the rod is free of load,” is satisfied without restriction, and the slightly longer distance for clamping is not relevant for safety. 
  • The spring-base also compensates for any misalignment between the load guide elements and the clamping rod; therefore, the other compensation techniques are not necessary.

 

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