Forum Discussion
139 Replies
- MPondExplorer
FormerBoater wrote:
I think the link below will clear up what appears to be quite a bit of confusion here.
Cut and paste into your browser and give it an easy read.
http://www.idealease-abetterway.com/safetycompliance/04_22_2011.pdf
...
That was an interesting article, and probably useful for those new to DPs & air brakes. But I laughed at the second section "CVSA Lists 10 Things You Need to Know about Commercial Vehicle Brakes", specifically item #1:1. Commercial vehicles are powered forward by fuel. They are stopped by brakes that use heat as their energy
source. Brakes are vital to the safe operation of a vehicle because they enable the vehicle to stop.
Last time I checked, brakes don't use heat as their "energy source"... brakes use friction to convert kinetic energy into heat energy, which in turn slows the vehicle down. - slickest1ExplorerGoing from driving a vehicle with hydraulic brakes to air brakes there are notable differences. Hydraulic brakes, if the pedal goes soft or down you should know you have a problem coming.
Air brakes, the pedal feels the same pretty much all the time. If the brakes are set up and you make a fast stop it does not take much pressure on
the pedal to achieve that. As the adjustment get loose the force needed on the pedal increases similar to regular brakes but not as noticeable. This happens over time and miles and on a motorhome it probably takes awhile before the adjustment changes significantly. What does happen is people get complacent and the brakes work fine in stop and go traffic. The kicker is when all of a sudden you have to make a panic stop and your standing on the brake pedal and it is not stopping fast.
Some of the experience on here offers some good good advice to people new to DP's and air brakes.
No you don't have to get under your coach every time it moves, but you should realize it needs to be done periodically and either know or learn how to do it or have it done and know your not getting ripped off by some unscrupulous mechanic. There are responsible people on the road and then there are the ones who thumb their nose at someone trying to give good safe responsible advice.I really don't know what microwave ovens and airplanes have to do with air brakes. Sheesh! - peaches_creamExplorerAfter all this discussion, I think I will get out of this "beast" and go back to something simple like "flight instruction". Anyone want to purchase a slightly used Ambassador?
- Tom_AndersonExplorer
FormerBoater wrote:
-Automatic slacks adjust themselves only if the brakes are engaged > 60%.
-In normal operation the brakes are engaged far less than 60%
The spring brakes engage the brakes at least 60%. So, as long as you use the parking brake regularly, you're covered.
One of the posters here said that going through the adjustment procedure will not effect brake pedal travel. In my coach (Meritor brakes) this is certainly not true. If the slacks are not calibrated/adjusted you may encounter a situation where you are fully stroking the brake pedal (pedal to the metal) and your brakes are not 100% engaged.
I didn't say the brakes would be 100% engaged if they were out of adjustment. I said the pedal travel wouldn't change. Are you saying that if your pushrod travel is 1", your brake pedal won't go down as far as it will if travel is 1-1/2"?
For those who leave their opinion here that you should be measuring or having mechanics adjusting automatic slacks...here is a video with a read from the NHTSA manual.
http://www.youtube.com/watch?v=NnGi_lqueo0
I couldn't bring myself to watch that whole video, but I skimmed through it and I didn't see the part where it said not to check or measure pushrod travel. And I missed the part in this thread where anybody said you should manually adjust automatic slack adjusters. - FormerBoaterExplorerI think the link below will clear up what appears to be quite a bit of confusion here.
Cut and paste into your browser and give it an easy read.
http://www.idealease-abetterway.com/safetycompliance/04_22_2011.pdf
A few of the main points made are:
-Automatic slacks adjust themselves only if the brakes are engaged > 60%.
-In normal operation the brakes are engaged far less than 60%
-10 full stroke actuations are recommended.
-One of the primary reasons for diminished brake performance is due to glazing which occurs when the brakes are not minimally engaged.
Many MH's are subject only to light braking due to driver reliance on exhaust or engine brakes. So, a full hard stop periodically done in a parking lot is a best practice IMHO.
One of the posters here said that going through the adjustment procedure will not effect brake pedal travel. In my coach (Meritor brakes) this is certainly not true. If the slacks are not calibrated/adjusted you may encounter a situation where you are fully stroking the brake pedal (pedal to the metal) and your brakes are not 100% engaged.
As I keep my slacks calibrated, I get to 100% of braking capability well before I reach the "pedal to the metal" stage.
Several years ago an American Coach was involved in a multi-vehicle accident on I-95 in N.C. The road was closed for hours...the owner was not aware of the calibration procedure and had never calibrated his slacks. Traffic was at a standstill and he did not have 100% of his braking capability. He was "pedal to the metal", but could not stop his coach before plowing into the traffic.
Properly calibration of the slacks by using the full stroking procedure ensures that 100% of the braking capability is available to you.
For those who leave their opinion here that you should be measuring or having mechanics adjusting automatic slacks...here is a video with a read from the NHTSA manual.
http://www.youtube.com/watch?v=NnGi_lqueo0 - Executive45Explorer IIITo those of you who are trying to belittle the purpose of checking your brakes, I would ask that you stop as your posts might confuse someone who is just starting out with a DP and air systems. These systems should be checked on a regular basis. Should we have to check them several times a day? of course not. Should we KNOW HOW...? an emphatic YES!...
As a former LEO who worked truck inspections in California, here's the biggest issue with commercial trucks....the driver owns the tractor and is delivering trailers for another firm as an independent. Since brakes are expensive to replace, they back off the adjustment on the TRACTOR (their own $$) and use mostly the trailer brakes for stopping..(someone else's $$). If you get a chance and are interested, stop by one of the local State Inspection stations and hook up with one of the inspectors...you'd be surprised at what you find...they are not just looking for overweight vehicles....
BTW...in California, at least, if you're found overweight, overlength, mis adjusted brakes etc. you can be cited as an unsafe vehicle. As such, you can be required to PARK your vehicle until in compliance or your vehicle can be TOWED because of the violation...not saying they WILL, just saying they COULD...and yes, I've done both....be safe out there.....Dennis - Tom_AndersonExplorer
msmith1199 wrote:
Tom_Anderson wrote:
msmith1199 wrote:
"You would fail the CDL test. You forgot the walk around which requires actual checking of the slack adjusters and brake pads, drums or rotors"
You're supposed to do a walk around and check brake pads? I could not do that with a walk around, at least I don't think. I'd have to do a crawl under and I'm pretty sure even with crawling under on the drum brakes you can't even see the pads without taking the drum off.
Yes, if you're driving a commercial vehicle, you are supposed to do a complete inspection every day. Obviously, if you can't see the brake shoes without removing the drums, you're not expected to check them. Again, this is only for commercial vehicles, or the CDL driving test.
But I think people are arguing you should do the exact same for your RV as is required by the CDL. Once nice thing about the big rigs is many of these things are readily available to see. They aren't so easy to see on a motorhome.
Yes, that is what some people are arguing. I'm not one of them. ;)
I think it's about time to put this discussion to bed and talk about something we can all agree on, like whether or not you need toad brakes. :B - Tom_AndersonExplorer
randco wrote:
Tom, somehow I think you missed my humor.
I guess I did. :B
There's just so much seriousness in this thread, it catches me off-guard when somebody is actually joking. :p - msmith1199Explorer II
Tom_Anderson wrote:
msmith1199 wrote:
"You would fail the CDL test. You forgot the walk around which requires actual checking of the slack adjusters and brake pads, drums or rotors"
You're supposed to do a walk around and check brake pads? I could not do that with a walk around, at least I don't think. I'd have to do a crawl under and I'm pretty sure even with crawling under on the drum brakes you can't even see the pads without taking the drum off.
Yes, if you're driving a commercial vehicle, you are supposed to do a complete inspection every day. Obviously, if you can't see the brake shoes without removing the drums, you're not expected to check them. Again, this is only for commercial vehicles, or the CDL driving test.
But I think people are arguing you should do the exact same for your RV as is required by the CDL. Once nice thing about the big rigs is many of these things are readily available to see. They aren't so easy to see on a motorhome. - randcoExplorerTom, somehow I think you missed my humor.
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