Fanning your brakes will not allow them to cool so that they won't overheat on a steep downgrade.
Even when you fan the brakes the brakes can still overheat when on a steep downgrade.
Fanning reduces air pressure and serves no useful purpose on dry pavement, and fanning on a long downhill grade may reduce air pressure below the minimum pressure needed for proper brake operation.
Brake linings do not get hot when fanning.
The short time off the brakes does not allow the brakes to cool.
Why should you NOT fan brakes on and off during long downgrades?
Does not allow brakes to cool.
If you must make a quick emergency stop, you should: Stay in a straight line and maintain control.
Why should you not use the trailer hand brake to straighten out a jackknifing trailer?
Because the brake handle is too hard to reach.
Because the brakes on the trailer wheels cause the skid in the first place.
Because the brakes on the trailer wheels will not respond to the hand brake.
The brake drums cool very slowly and the brakes may begin to fade and have less stopping power when the pressure is not applied steadily.