One of the newest applications of the Technogrid® is the arresting of the conveyor counter weights. In some applications, if the belt snaps and the counter weight falls to the ground, there is no damage done and it is not an issue. In other cases, however, if the counter weight falls and does serious damage to structures or equipment below, then counter weight arresting needs to be considered.

The Technogrid® provides the ideal solution to this problem. The specified Technogrids are simply 'hung up' vertically next to or below the counter weights with a catch frame attached to the bottom of the Technogrids. The catch frame is situated just below the lowest point of the normal vertical movement allowed for the counter weight. The top of the Technogrids are anchored to the structure. The structure must be verified to ensure that it can handle the impact forces which are generated by the impact (see data sheet for end forces). Upon impact, the Technogrids will stop the counter weight and absorb all the energy and the counter weight will remain on the catch frame until reinstalled on the repaired conveyor belt.

After a full impact, the Technogrids simply need to be replaced and then the Technogrid arresting system is ready for the next impact. The Technogrids available for this application range from 12kJ to 225kJ (see data sheet for options) and can be used in any combination of series or parallel up to 5000kJ.

GENERAL NOTES

1. The crash beam should be installed just below the point of normal travel of the conterweight so as not to interfere with the normal movement of the counter weight. This also reduces the impact energy that needs to be absorbed.
2. The Technogrids can be installed in any configuration from 2 or 4 grids in parallel or strings of technogrids mounted in series in 2 or 4 strings.

FORMULAS USED IN THE CALCULATION PROCESS

E = m.g.h
E = energy
m= mass of counter weight
s = stroke of technogrid
h = maximum fall distance of counter weight (h = T + s, s is the stroke of selected unit).
n = number of technogrids used in parallel

WORKED EXAMPLE OF SPECIFYING YOUR TECHNOGRID

Parameters of example
m     4 tons
T     2m
Y     5m

CALCULATIONS

Assume a stroke of a technogrid, we chose a 60kJ technogrid which has a stroke of 650mm.
Use the data sheet to choose the technogrid with its maximum stroke



Two 60kJ technogrids will absorb the 103.9kJ of total energy with each technogrid absorbing 51.95kJ.

HOW TO READ THE GRAPH

1. Take the energy value and read off from the right hand side of the graph inwards until the energy curve is intersected.
2. Extend the intersection point vertically in both directions until the force curve above is intersected and the stroke distance of the technogrid is intersected on the bottom.
3. Where the vertical line intersects the force curve, move horizontally to the left and read of the end force of the technogrid.

In this example: 51.95kJ intersects the energy curve at a stroke of approximately 590mm and the end force per technogrid is approximately 131kN.

Horne offers a free design service for specifying the counter weight technogrids. This brochure is intended as a guideline and the brochure is used at your own risk. It is advisable to contact Horne for the verification of design calculations.