How Safety Locks Provide Static Securing for Lifted Loads

Jul 16, 2018

 

Static Securing with Self-Reinforcing Clamping

 Hydraulic or pneumatic pressure holds the safety lock open. At pressure loss, safety locks block a static load in the load direction on a cylinder rod or a separate rod. If the load starts to move down, the clamping system closes in a self-reinforcing function -- the higher the load, the higher the clamping force. This provides static securing for applications such as:

  • Support cylinders at heavy-load vehicles

  • Lift cylinders in scissor-type lifting panels and theater lifting podiums

  • Tool trays

  • Lifting tables in packaging and machinery and pelletizers

 Safety locks do enable high loads to be held by a compact unit, but they are not suitable for overloads and impact forces (such as when braking masses).

 

Function and Design

For static securing, the safety lock clamping system consists of a conical clamping sleeve that moves within the conical housing. The annular piston (hydraulic or pneumatic) keeps the clamping sleeve released by pushing against a set of disc springs, allowing the shaft to move freely within well designed radial clearance.


The safety lock secures the load as soon as pressure is released from the annular piston. The clamping sleeve is then forced into the cone of the housing by the disc springs, creating a situation of initial friction contact between the rod and clamping sleeve. At this point, the Safety Lock secures the load but has not yet taken the
load.


The force is not built-up until the rod has been moved by the load. The self-intensifying process draws the clamping sleeve further into the housing and contracts the clamping systems. The movement of the rod is very small during this process. Even with bigger loads, it does not exceed 2 mm if the admissible load M is applied.  


To release the clamping of the load, and upward movement of the rod is necessary in addition to the released pressure.

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