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GWolfe

Kansas

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Posted: 02/22/20 06:00am Link  |  Quote  |  Print  |  Notify Moderator

IdaD wrote:

ShinerBock wrote:

And it is not a theory that Mr truck has been wrong before.


Yeah, he's consistently grabbing vests that are about three sizes too small.


That was great I did LOL at that one!


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4x4ord

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Posted: 02/22/20 06:57am Link  |  Quote  |  Print  |  Notify Moderator

CaLBaR wrote:

4x4ord wrote:

With the Ford the brake lights only come while the wheel brakes are applied. The Ram is probably the same.


In my owners manual it states that the brake lights come on when the exhaust brake is active letting other drivers know that you are slowing down.

Rob


That's interesting but I think it is likely wrong. On my truck the brake lights only come on when the wheel brakes are applied .... when descending a grade at night I can see the brake light reflection off my trailer and the brake lights only come on when the wheel brakes are being activated. Even without the EB turned on and without a trailer hooked up, my truck will activate the wheel brakes going down a steep hill if cruise is set and the truck is wanting to accelerate down the hill. When the computer activates the wheel brakes the brake lights illuminate.


Edit: In the video we can be sure that the EB was on while that Ram was going down the hill and we can see the brake lights were not illuminated.

* This post was edited 02/22/20 07:04am by 4x4ord *


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4x4ord

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Posted: 02/22/20 07:30am Link  |  Quote  |  Print  |  Notify Moderator

I did an experiment with my Ford and determined that the Ford exhaust brake will produce about 170 reverse HP at the rear wheels (at 3500 engine rpm) ... likely about 145 at the crankshaft. Without the exhaust brake turned on the engine will produce about 62 negative HP. Drag and rolling resistance at 50 mph on a typical truck and 5ver is likely equivalent to about 80 negative HP. So the total resistance on my truck and trailer with the exhaust brake working at maximum capacity is about 250 negative HP at 50 mph. My 24000 lb truck/trailer on a 7% grade needs about 225 negative HP to hold it from accelerating.

Based on what I have experienced towing in the mountains the above seems about right. It takes an 8% grade before I will see may wheel brakes applied to supplement the exhaust brake.

Edit: Cummins: you need 382 reverse HP at the rear wheels of your truck to keep your 33k lb combined unit from accelerating on a 14% grade at 35 mph.

* This post was edited 02/22/20 07:45am by 4x4ord *

Cummins12V98

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Posted: 02/22/20 08:41am Link  |  Quote  |  Print  |  Notify Moderator

CaLBaR wrote:

4x4ord wrote:

With the Ford the brake lights only come while the wheel brakes are applied. The Ram is probably the same.


In my owners manual it states that the brake lights come on when the exhaust brake is active letting other drivers know that you are slowing down.

Rob


This must be new for 2019?

Does it say anything about actually applying the truck or trailer brakes when EB is active?


2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's
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Cummins12V98

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Posted: 02/22/20 08:45am Link  |  Quote  |  Print  |  Notify Moderator

Since no one responded to my question about when the CUMMINS was at 3,500rpm I will answer it my self. I watched the entire downhill and the MAX rpm it was turning was 3,250 right against the redline.

Cummins12V98

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Posted: 02/22/20 08:50am Link  |  Quote  |  Print  |  Notify Moderator

"Cummins: you need 382 reverse HP at the rear wheels of your truck to keep your 33k lb combined unit from accelerating on a 14% grade at 35 mph."

Something does not jive! I was locked in 2nd right against the redline or close to it. You had mentioned that section varied in grade as does the Ike. Who knows, I just know it did what it did.

Makes ya wonder how accurate these signs are????

Bionic Man

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Posted: 02/22/20 10:31am Link  |  Quote  |  Print  |  Notify Moderator

The 2020 RAM owners manual is here.

The towing section looks to start at 318. The exhaust brake section is on 230.

I don't see anything that talks about applying brakes when the EB is on, nor applying the brake lights. But I didn't read the whole thing.


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Me Again

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Posted: 02/22/20 11:47am Link  |  Quote  |  Print  |  Notify Moderator

Cummins12V98 wrote:

Like I said no one really knows how much fuel these trucks use. FISH what you say now?

So as 4x4ord mentions the 10 speed would have not made any difference. Did y'all see how cool the trans runs? YUP just like mine nice and cool.

Did y'all see how well the truck keeps the truck at speed downhill with the cruise on as I have mentioned many times? Heck I was holding 35mph at 14% in second for miles at 33k combined.

Rear air heck yea I know how well it works and yes my 15's steering is like being on rails unloaded and at full RAWR of 9,750# with a combined 35k.

SAE Towing capacity is 3k higher than the other two.

So bottom line I will gladly take a truck that is a bit slower up the hill with a "True Medium Duty" engine and transmission that will do this day after day and WILL get me down the grade with ZERO brake applications and the BEST part COLD brakes!


Did you notice the rear leafs of the factory air ride were different from yours? Chris


2015 RAM 3500 CC SB SRW Our Rig New 2017 Bighorn 3575el. Commuter trailer 2019 Laredo 225MK. Retired and enjoying it!


4x4ord

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Posted: 02/22/20 12:20pm Link  |  Quote  |  Print  |  Notify Moderator

Bionic Man wrote:

The 2020 RAM owners manual is here.

The towing section looks to start at 318. The exhaust brake section is on 230.

I don't see anything that talks about applying brakes when the EB is on, nor applying the brake lights. But I didn't read the whole thing.


I think the idea of all the electronics is to make the trucks simple to operate. Just put it in drive, push the auto EB button and go. The danger of explaining things in the owner's manual is that, unless things are explained to great length, it might confuse more people than it helps. Some would read that the auto button will apply wheel brakes on the down hill grade and think using auto could overheat their brakes. Auto is designed to be used not avoided.


Edit: I looked in my Ford owners manual and like the Ram manual, it says nothing about the Auto EB mode controlling the brake lights or wheel brakes.

* This post was edited 02/22/20 01:11pm by 4x4ord *

4x4ord

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Posted: 02/22/20 01:18pm Link  |  Quote  |  Print  |  Notify Moderator

Cummins12V98 wrote:

"Cummins: you need 382 reverse HP at the rear wheels of your truck to keep your 33k lb combined unit from accelerating on a 14% grade at 35 mph."

Something does not jive! I was locked in 2nd right against the redline or close to it. You had mentioned that section varied in grade as does the Ike. Who knows, I just know it did what it did.

Makes ya wonder how accurate these signs are????


Makes me wonder if the computer isn't programmed to apply wheel brakes at the engine red line to prevent over revving the engine.

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