Spring Base
for Safety Catchers
Spring base – Simulation
Spring base
Due to their design principle, SITEMA Safety Catchers can only be released if their clamping system is not under load – which is generally in accordance with the relevant safety regulations. If, however, the load overshoots after switching off the pressure, or moves slightly downward for any particular reason, the Safety Catcher is subjected to a partial load. In practice, this means that the load must first be raised before the Safety Catcher can be opened and before a movement in load direction is possible.
This effect, often found to be disturbing and time-wasting, can be avoided by not bolting the Safety Catcher directly to the machine frame, but rather on top of a spring-base. For its working principle, see the Simulation with spring-base.
A20 – Dimensions, Spring Base compressive load versionsAdvantages
- Even if the load slowly sinks down during normal operation, e.g. due to a small leakage at the lifting actuators, it is not necessary to lift the load before any downward movement.
- The crucial safety criterion “Safety Catcher can only be released if the rod is free of load”, is satisfied without restriction.
- The spring-base also compensates for any lateral misalignment between the load guide elements and the clamping rod. Therefore, other compensation techniques are not necessary.
Mounting
The spring-base is factory-mounted on the Safety Catcher, ready for use. Special mounting instructions are supplied for retrofitting.
For the compressive load versions, there are two alternatives for attaching the Safety Catcher to the machine frame, either by using threaded holes arranged identically to the ones on the Safety Catcher or via the shoulder which fits to the coupling flange FL/FS (see mounting flanges).
The tensile load versions are fixed to the machine frame by screws.
Other accessories for the product
Mounting Flanges
The standard SITEMA Safety Catchers (compressive load versions) are equipped with a set of threaded boreholes to fix the unit to the machine frame. However, often a mounting flange is required because either bolting from below is not possible or a floating attachment is necessary to compensate for possible misalignment. SITEMA offers various types of flanges for standing or hanging, floating or fixed mounting. Flanges for Safety Catchers with spring base are available as well.