down shifting on a downgrade

Sometimes mountain grades sneak up on you. Like going up hwy 97 in the British Columbia interior. In the southern parts of the province they have lots of signage, in the northern parts they cheap out. A few areas they like to wait until you're already rolling down a pretty good hill, then they put up the sign to say 8 % for the next 5 km(3 miles) Now what do you do?
You're definitely going to be dropping gears real fast. When ever I ran into one of these situations, I found it best to just get on the brakes, and get it down quick while the brakes are still cold and down shift to the appropriate gear.

 

Not much to add here since the best advice has already been given. IMHO if you're having to downshift on a downgrade then you were definitely in the wrong gear from the time you hit the top of the hill. But, if a grade sneaks up on you, then uncleal13's advice is equally valid; brake to a much lower speed while your brakes are still nice and cool, then downshift to a more appropriate gear. Just don't take too long doing it, otherwise you're just going to end up accelerating (in neutral) right back to where you started, and it's going to be a pain trying to get it back into a slot.

 

what is the most common way to slowdown on a downgrade? lets say if you are already on a lower shift, do you simple not apply any gas, or touch the pedal brakes often

 

If you must use the brakes then the most common method would probably be "stab braking". You apply the brakes nice and steady until you get to around 5mph slower than your target speed, then let off until the truck reaches the target speed. Rinse, lather, repeat.

Handling a downgrade is sort of like parachuting from a plane; what you're trying to achieve is a slow and steady controlled descent. Doesn't matter much how fast you're going. Like the old saying goes: you can always descend a mountain too slowly; but you'll do it too fast only once.

 

Downshifting was the one thing at CDL school I had trouble with. Especially double downing before a light or something. My instinct was to rush, probably because I had trouble looking at the road, the speed, and the rpms along with shifting and flipping the switch.

 

I learned how to shift in the right seat and sitting on the doghouse over many summers. I can get it in gear without cramming it. I have worked with guys who did not have that ability yet. One guy the company where I was working, not as a driver, sent me with a corporate maintenance guy to get his license. When he missed a shift, it usually would take him until the truck stopped before he could get it in gear. If down shifting scares you, it is best not to do it downhil, until you feel comfortable downshifting just going down the road.

 

Sure, you can downshift on a steep grade but only if you can set the engine RPM to match the truck speed. However, sometimes you might get off the Interstate and find yourself hillbilly highway with a full load, on a 10 percent grade, and forced to downshift and stab the brakes to reduce speed. No problem, until half way down the mountain the brakes are hot, glazed and starting to smoke.....the engine is red-lined, jake is useless, downshift doesn't help.

What should you do?

 

What should you do?
No perfect answer, every situation is unique. I did have a runaway once, but I knew the highway levelled out just a few more miles ahead. So I just rode it out. Started out up top at 35 mph, wound up at 85 mph.
Inexperienced with going down a long grade with my first tri-axle at 102,000 lbs. later I started that hill at 25 mph and it worked out much better.
The only difference experience proves is that you got lucky at the right moment while another guy didn't.

 

Wake up Earl.



'Cause he ain't never seen a wreck like this.

 

Ahhh just put er' in Georgia Overdrive. Can Dave Dudley be wrong?!!! LOL