How Safety Catchers’ Self-Intensifying Technology Secures Heavy Loads

Jun 07, 2018

Safety catchers are used to prevent catastrophic crashes in case the loss of hydraulic or pneumatic pressure occurs suddenly in certain applications such as hydraulic presses and freight elevators. The clamping system grasps the rod by means of pre-tensioned springs and secures the load with a self-intensifying principle that is similar to a wedge system.



Self-Intensifying Technology Advantages

The self-intensifying technology of a safety catcher is similar to how a Chinese finger trap works -- the harder you pull your finger to get it out of the trap, the more clamping power the paper toy exerts on your finger.

As the downward force of a fallen load increases, so too does the safety catcher’s clamping force. The safety catcher is depressurized to secure the load, which brings the clamping system into contact with the rod and then secures the load. Only when the load moves downward does the clamping system contract and hold the load. Other advantages of self-intensifying technology for protecting workers and machinery include:

  • Release under load is impossible, thereby automatically ensuring safety against unintentional release. 
  • Release is possible only after relieving the clamping head, automatically ensuring safe load transfer.
  • Consequently, release is also gentle when used on cylinders.
  • The clamping system is loaded only when this is actually necessary. 
  • This ensures a long service life (B10D values up to 6 million). 
  • Safety factor > 2 built in. 
  • Upward movement is possible even in a depressurized state, e.g. to rescue trapped persons. 
  • Loads up to 220 kN can be secured pneumatically as well. 
  • DGUV approval on all standard Safety Catchers and safety brakes.

Self-Intensifying Technology vs. Non-Self-Reinforcing Clamping Systems

Other protection systems are available to ensure operator safety, such as guards, interlocks, electro-sensitive and opto-electronic devices, emergency stop devices and more. However, when compared to the self-intensifying technology of safety catchers, non-self-reinforcing clamping systems have a few disadvantages when securing suspended loads:

  • Release is possible under load as well so the load to be secured can still fall down. 
  • Release is possible even without prior load transfer, potentially resulting in a hazardous situation. 
  • Depending on the pressure on the cylinder, the load will dip down or jump up on release. 
  • The clamping system is under full load at all times which shortens the service life. 
  • Safety factor is generally not included. 
  • It is not possible to move up in the event of a pressure failure. People may remain trapped. 
  • High holding forces are generally possible only by hydraulic means. 
  • Generally no DGUV approval.

With the self-intensifying technology, relief automatically ensures that another system has safely taken over the load before the clamping system can be opened, saving in downtime, machine replacements, and operator injury.

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