CDL Test question on brakes

This really makes sense because I've noticed other places in CDL guide where brakes are referenced generically. Thanks.

 

As a newbie, I'm really enjoying the smart way these truck systems are designed. There's more to it than meets the eye.

Appreciate the responses from so many sharp folks. This forum is a real treasure!

Thanks again,

Mark

 

Don't set them ####### when right away in the winter either after you get off the road. Them shoes will freeze to that drum by morning and then you get to buy a 3lb hammer and beat like a SOB for about 45 minutes to get them unstuck...don't ask me how I know this.

 

You are using the exact same braking surfaces and friction surfaces between the service application and the parking application. In fact, the spring that applies the parking brake is mounted in a second chamber behind the service chamber. This differs from automobiles to some extent that some manufacturers in a 4 wheel disc system, will employ a drum/disc on the rear brakes so you have a disc brake setup for all service applications and the standard drum assembly for the parking brake. We don't employ that type of system in heavy vehicles which is why you will not have parking brakes if you have no service brakes.

 

379exd has been to Colorado too! YUP! YUP! Had it happen in the San Louis Valley more than once, one time at the fuel pump and the guy standing there screaming all the time so I got out a flare and he went back inside.

 

Didn't miss the point at all. It's the way he worded his question.

 

Yea, but, in a controlled environment, it would be awesome to see!

- Steven

 

Had one of those brake drum grenades go off on me a couple months ago.
Picked up a 53' with supersingles from Chicago, got about 1.5 hrs west and the right front drum on trailer went MIA in chunks of shrapnel.
Only thing left was the drum's faceplate between hub & wheel. Supersingle had big holes torn thru it.
All other kinds of associated damage (RR chamber, brake hose, trailer floor, etc).
Expensive (not on my $)... but not pretty.

 

A number of people did miss the point.

If someone was just reading the last line of my question or if they didn't really understand how truck braking systems work then they could say that parking brakes are not used when coming down a hill. But that DOES miss the point.

The point was to answer why parking brakes should not be used after service brakes get heated after coming down a steep grade. The answer, as heyns57 pointed out, was that because brakes share the same components, when service brakes get heated even the parking brakes (because of shared components) are also heated.

Obviously, everyone's trying to help out. But heyns57 and KW Cajun (along with a few others) provided answers WITH explanations and experience. It really helps move newbies, like me, forward and do more than memorize test answers. If we understand how the trucking systems really work then we'll be better drivers. Ultimately, I think that's the bigger point.