Long downhill driving is extremely demanding on the brakes. The
drivers need to aware of this and should not underestimate this. If you
are on a slope of 6% over 6 miles the change in elevation will be 199
feet. A free fall from that elevation (1900 feet) will generate a
velocity of 235 mph. That is the velocity your truck will have if you
do not use brakes. This means breaking while negotiating this slope is
slowing down from 235 mph. You will need to do a lot of stopping.
Therefore it is absolutely necessary that you use the right braking
technique and your brakes be in proper condition too.
Not so long ago it was suggested that a continuous application of
brakes should be followed rather than intermittent application. But now
most experts believe that intermittent braking on a downgrade is the
proper way to brake. On a downgrade each application of brake should
reduce the speed of a fully loaded truck by about 5 to 6 mph.
Theoretically, the same amount of heat will get generated whether you
jam the brakes by continuous application or apply them intermittently.
But in practice unless the brakes are in perfect condition, the balance
is correct and load is evenly spread, the continuous application of
brakes is likely to result in uneven drum and lining temperatures that
will cause problems with braking. Steady, low pressure application of
brakes may not cause all the brakes to apply at the same time. This can
cause some brakes to more work than others. Brake problems can get
aggravated by this technique.
For best results you need all the brakes to work at the same time. The
pressure applied on the brakes should be high enough to ensure all the
brakes apply and all linings make solid contact with the drums.