Ignoramus20398 wrote:
On 2012-03-04, Pete C. wrote:
Ignoramus20398 wrote:
On 2012-03-03, Karl Townsend wrote:
On Fri, 02 Mar 2012 21:28:21 -0600, Ignoramus22470
wrote:

On 2012-03-02, Karl Townsend wrote:
On Thu, 01 Mar 2012 23:03:30 -0600, Ignoramus6107
wrote:

I have been practicing and driving my semi tractor almost every day
recently. Not much time every day, but I usually manage to find at
least some time every day. At my age and after 17 years of driving
auto transmission, the skills to drive a truck with an unsynchronized
manual transmission do not come easily, but I am making progress. I
can now shift up and down, and by now, it works well most of the time.

I will soon try to pass a theoretical exam to get a CDL learner's
permit.

i
You're learning at a better age than myself. I started driving
truckloads of wheat to the elevator at 14. Dad told me to never go on
the highway. Of course, I ignored that. I forgot to down shift at the
top of pleasant grove hill. When the brakes wore out, I tried to down
shift and missed it. That old truck was doing 80 at the bottom of the
hill. I was lucky to see 15. But, I've never forgot to down shift
again.

I have found a golden guy, an honest mobile mechanic, I will have him
check my brakes out.

i
Iggy, just in case you don't alread know, NEVER go down a hill in a
gear higher than you go up it. Downshift at the top. No matter how
good the brakes are, it won't stop 80,000 lbs. I just told you how i
learned this.

Karl

Karl, I am aware of this, yes. I think that proper brakes are enough
to slow down downhill and to switch to low gear, but I am aware of the
brake fade phenomenon.
The problem is not the brake fade, the problem is if you do not do your
downshift before you go over the crest of the hill, you have very poor
odds of being able to successfully complete the downshift on the
downgrade. What happens is you get it out of gear and then you are
unable to get it into the lower gear and often you can't get it back
into the previous gear as well. This leaves you on a downgrade in
neutral with *no* engine braking at all and your service brakes won't do
the job. It's runaway truck ramp time if you are lucky enough to find
one.

OK, I will bite, why would the service brakes not do the job and stop
the truck, at least once?

i

Mainly because by the time you realize that your NEVER going to get back
into gear you have already stabbed the brakes a half dozen times trying
to slow down and they are now HOT.
If they were stone cold when you hit them they would probably stop you
once, they would likely burn up from the heat and maybe set your rig on
fire but they would stop you.
When they are HOT, you may as well head for the wall/bank/run off ramp.
They lose a LOT of braking power once they heat up and start out gassing
then they start glazing over then it's game over. Glazed brakes are
about as effective at stopping as a block of jelly is at stopping a
chainsaw.

--
Steve W.