Brakes smoking!

[Robbbyr]

The exhaust brake on a diesel (at least on commercial trucks) will lock down or limit the valve travel to make the cylinders big compressors. While proper transmission gear still needs to be selected, the addition of the right gear and exhaust braking will be a vast improvement over a gas engine simply using the engine drag.

I agree with all advise. It is probably not that you damaged your brakes (they will take a lot of heat) but you should have them inspected. Damage will show up as discoloration and probably warpage to the rotor (are these drum or disc on the Seneca? I don't know). If no issues, then keep rolling, but control your descents with combination of transmission, engine brake, and lastly, wheel brakes.

Thanks for being brave enough to post so others can learn.

Just a slight correction on Seneca exhaust brakes. The exhaust braking on our units is accomplished by the computer changing the vane position on our variable geometry turbocharger which increases exhaust back pressure. What system you described, acting on the engines valves, is an Engine Brake which operates differently but accomplishes the same thing. Larger Cummins engines can be fitted with an engine brake but they only use exhaust brakes on the Seneca ISB. Engine brakes tend to generate more "braking horsepower" than an exhaust brake generally can. Very useful on even heavier trucks as you might imagine.

And through the wonders of computer integration our exhaust brakes work in conjunction with the transmission. As one applies light brake pedal pressure the transmission will automatically downshift to increase exhaust braking effectiveness. That is of course assuming the vehicles road speed will allow for a downshift without overspeeding the engine by doing so. It will continue to drop gears until it cuts out at 15 mph where one must use the foundation brakes to bring to a complete stop. Obviously this is assuming that the exhaust brake is in the "on" position. Turned off, the unit will just coast like any other rig.

And air brake-equipped Senecas (2016 - up) do have drum brakes all around. However early Freightliner Senecas (up through 2015) have four wheel hydraulic disc brakes with power steering boost.

 

[Mel41]

Thank you so much for your reply! When I told my hubby I was going to post the question (neither of us knew! About exhaust brakes) and he did say I was going to get some very patronizing responses.....and I did get 1 or 2 non helpful replies as is clear, however I also got some very kind and informative answers, which were very much appreciated, thank you to those who took the time! I have driven large horse carrying lorries in the UK for many years and never had seen exhaust breaks before, so definitely a learning curve! Glad I asked the question.....I was always taught ‘the dumbest question is the one you don’t ask!!’
Yes, the lorry is booked on for a check over!
(Ps just got to respond to those that assumed I rode the brakes all the way.....No I never, I definitely knew that much about laden lorries and hills!!)

 

[Oma/opa]

I'm not sure this was mentioned but slowing down before cresting the hill will make a great difference in controlling your speed going down.

 

[Mel41]

Just to let you all know, we’d taken the RV to have the brakes checked out and apparently all the brakes were too tight and had to be adjusted! The garage was in no doubt that would have caused the issue! Not just a dumb woman driver after all!!

 

[McGintys924]

I would agree with many that you are very fortunate that everything ended well at the bottom of the hill and at Freightliner.

Since we know you are both safe after this experience, I will share this video. It’s Hollywood’s rendition of using too much breaks.

We all are going to miss things and learn from each other here. Some lessons are free; enjoy those.

https://youtu.be/AuMwh4hiL9g

 

[Russ661]

https://youtu.be/AuMwh4hiL9g
Let’s see if this link works....yep, works for me!

Regarding the original posters experience, in my Ram diesel with auto trans I can put the vehicle on cruise control with the trans in Tow/Haul mode and the exhaust brake set on automatic and the computer will keep my speed within a few mph of what I have it set to even on steep grades while towing.

 

[Farris7]

What Slopoke said. Get off the pedal as much as possible.

 

[pconroy]

I completely agree with Rob. The worst thing you can do is drag your brakes. Get on the brakes with authority (don't slam, but firm) to slow down below your target speed. You want to spend as little time as possible "on the brakes".

this.


when you need to brake coming down a hill, get on 'them.
slow down 10mph below target and then get off them!

 

[namusmc65]

https://youtu.be/AuMwh4hiL9g
Let’s see if this link works....yep, works for me!

Regarding the original posters experience, in my Ram diesel with auto trans I can put the vehicle on cruise control with the trans in Tow/Haul mode and the exhaust brake set on automatic and the computer will keep my speed within a few mph of what I have it set to even on steep grades while towing.

That video tends to give truck drivers a bad image! LOL

 

[McGintys924]

That video tends to give truck drivers a bad image! LOL

Sorry, it just what comes to mind from a movie reference.

I have to admit that most of my driving has been without a toad to this point and therefore my engine break has been sufficient for the hills of P.A. to NC. This next trip will be with our accord on a dolly (~3500lb). It has always impressed me how even a light trailer behind a large tow vehicle can affect things. Having a 5000 + lb pickup would definitely affect the breaking dynamics of your Seneca.

Not knowing anything about the 4down breaking systems I cannot comment there. However, could this system need further adjustment?

 

[Rickguns1956]

well... that explains why the overheated brake... and you may have damaged your rear braking components / bearings with this event.

You should get this into a Freightliner shop ASAP and have them inspect your entire brake system. Explain to them what happened so they know what to look for.

You should review the drivers manual on your rig... descending grades requires
specific actions and precautions, or you can overheat your brake system and lose your brakes entirely in worst case situations. You were lucky...

SloPoke nailed it so well!!! Correct gear, engine brake (Jake Brake), if the use of chassis brakes are needed then jab, release, jab...........it gives just enough time for the brakes to stay cooler and not get too hot. Try to start out at the top of the downhill that you want to be at when at the bottom. Apply brakes if you get 5mph more than you want.
Your brakes are probably now "toast".........burnt toast at that
I have put out several brake fires when I was on duty........they're tough. A extra fire extinguisher on board is never a bad thing.

 

[Purdue 1]

6% Grades

Just finished 2 weeks in the four corners region. Every time I was forewarned of 6% grade I would turn off OD and shift to third. Crawled down all of them at 35-40MPH never touched the brakes. Surge brakes on the toad working as needed.

 

[Edd505]

750K in an 18 wheeler, multi RV's with multi trips cross country. Go slow down hill, lower gears, exhaust brake if you have one. Old trucker saying: you can go down hill lots of times too slow, once too fast.

 

[srxhare]

exhaust brake with pic

On my rig it is located below the shift lever. It is not marked with any text but it is looks like the picture below.

Hi Robby do you have a picture of the Exhaust brake switch on your Seneca?

 

[Rustynuts]

Hi Robby do you have a picture of the Exhaust brake switch on your Seneca?

Here is a pic of the exhaust brake switch.

 

[Robbbyr]

Hi Robby do you have a picture of the Exhaust brake switch on your Seneca?

On mine.

 

[srxhare]

thanks much , that helps!!!