Attention: TDR Forum Junkies 
From the "Fire Chief" online newsletter. I get this newsletter every Friday and thought that the group should consider this when putting the piece of cardboard in front of the radiator. I beleive that the center hole that is recommended has merit.
Friday, December 14, 2007
Improperly Designed Winterfronts Can Cause Fan Failures
Dec 6, 2007 9:59 AM
Did you know that improperly designed winterfronts can cause fan failures? Some vehicle and engine manufacturers don’t allow the use of winterfronts, and other require specific designs.
The problem occurs when users install older winterfronts with V-shaped openings. These designs allow air flow through a wedge at the top and/or bottom of the grill and block flow at the sides. As the fan rotates, each blade alternately passes through areas of high and low air resistance, which makes the blade flex back and forth rapidly and can result in metal fatigue failures.
Some newer winterfront designs have a single circular opening in the center to allow a more uniform flow across the blades as they rotate. Consult your apparatus, chassis or engine manufacturer for information about the use of winterfronts on your vehicles.
Friday, December 14, 2007
Improperly Designed Winterfronts Can Cause Fan Failures
Dec 6, 2007 9:59 AM
Did you know that improperly designed winterfronts can cause fan failures? Some vehicle and engine manufacturers don’t allow the use of winterfronts, and other require specific designs.
The problem occurs when users install older winterfronts with V-shaped openings. These designs allow air flow through a wedge at the top and/or bottom of the grill and block flow at the sides. As the fan rotates, each blade alternately passes through areas of high and low air resistance, which makes the blade flex back and forth rapidly and can result in metal fatigue failures.
Some newer winterfront designs have a single circular opening in the center to allow a more uniform flow across the blades as they rotate. Consult your apparatus, chassis or engine manufacturer for information about the use of winterfronts on your vehicles.
