FREQUENTLY ASKED QUESTIONS

FAILING HEADS

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 Frequently Asked Questions

   

    Question:    What is the difference between a Four Inch Impact Head and a Five Inch Impact Head?

   Answer:     This is a Good Question and it is a Common Question. The Four Inch and Five Inch designation of the Impact Head represents the size in width of the Feed Channel that guides the Guardrail into the Extruder Chamber which returns the W-Beam back to it original state as a flat coil ribbon. The Four Inch Impact Head represents a Four Inch wide Feed Channel and The Five Inch Impact Head represents a Five Inch wide Feed Channel which was the original approved Model.

    Question:    How many Models are they of this Type of End Terminal?

    Answer:    They are several manufactures of these types of End Terminals but the most common are as follows: SKT350,  ET2000, ETPlus (With a Five inch Feed Channel and a One and Half Inch Exit Gate the Original Model), ETPlus (With a Five Inch Feed Channel and a One Inch Exit Gate), ETPlus (With a Four Inch Feed Channel and a One Inch Exit Gate).

    Question:   Why does this failure occur in the four inch model and not the five inch model?

   Answer:   They are several reasons, but the most prominent is this. When the manufacture refitted the new model with a Four inch Feeder Channel rather than the Five inch Feeder Channel a shortening of the Extruder Chamber vertically was created causing the deformation of the W-beam to restrict on the lower and upper Feeder Channels at the entrance of the Chamber. They never took in account of the location of the end of the Feeder Channel inside of the chamber was now the new point of measure and it was now 3/4 of an inch into the extruder chamber.  They never compensated in the Extruder Chamber for this new change.  Ultimately causing a shortening of over one and half inches vertically in the opening of the extruder chamber at that location. The fact that in the event of the extrusion of the w-beam the deformation does extend over eighteen inches outside of the extruder chamber back into the window of the Feed Channel. When this happens it creates a dead man's block, this is why through maintenance it is more common not to be able to reuse the 4" extruder head due to Throat Lock (The W-Beam will not go Forward or Reverse inside the Head).

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