Questions on engine brake use.

Depends on the engine. On my d13 I might not even have to drop a gear.

On my truck with a c12 I let them scream at 1800 rpms to get them to full power.

Sorry if I offend you with my old loud truck, you’ll live...

 

Jake brakes do the magic job of slowing the Truck down while using NO fuel. In effect, it turns the engine into a compressor. I have no idea how the idea that Jake's use fuel came about, but it just ain't so.
By the way, Jake's are called that because the first company that made a compression brake was the Jacob's Manufacturing Company. Clessie L. Cummins ( yes, the man who founded Cummins ) had "invented" it for diesels and held a patent on it. He had been forced out of the company that bore his name. Jake's work by releasing the pressure built up during the compression stroke right before Top Dead Center, immediately before the fuel gets injected and burns during the power stroke. Very little to no fuel is injected because the engine isn't being used to make power. The throttle is fully closed when Jake braking, the slightest touch on the throttle instantly shuts the Jake brake off. You can immediately hear it. And feel it.

 

There is a gear somewhere on every grade with a jake brake that matches the resistance to the downgrade force of your semi.

Once you find it you will find that you can stay in it all the way down more or less if you choose.

I like to load a gear up quite a bit near the red line. But anywhere at high horse is fine too.

If the rig see saws in a gear nosing down with too much jake, grab a gear and see how that works for you. Dont use the brakes unless you have to. It is a balancing you seek in the downhill. You will find it easily enough.

The trick is to ignore the road speed within reason. If Mt Eagle says 18 mph for 77000 gross or roughly that is what you start off at near the top at 15 or so in a gear that is somewhere between torque and high horse stage three jake to start.

When you reach the bottom and can actually SEE the run out to level ground, let her go she wants to run.

Eventually you will hit donner. Westbound. When the CAL DOT Signs tell you let her drift. that means flip the jakes off, stay off the brakes and you will find that gravity will drift her down at between say 25 and 34 varying mph for a while in the middle. It's one of the rare times you allow her to drift. It's a chance to cool off your braking mistakes if any.

I specialize in mountain. I was afraid of them in the very beginning on Big Savage west of Cumberland in school. Instructors took care of that. (There was no I-68 then, it was US 40 national old road)

 

I normally drive a 2018 with Cummins (not sure what motor exactly, some High Efficiency type), 18 speed, 129k, mix of flat and mountains. I try not to run RPM's over 1800 but Cummins tech told us 1900 while engine braking is fine on the motors we have. On the downhills (3-6%) I have the engine brake at the highest setting and normally in 5 Hi or 6 Lo. With that the engine brake will hold the truck back and stay under 1800 RPM and about 25 MPH. This still leaves me enough leeway to use a combination of service brakes and downshifting to get the truck slowed down should the engine brake fail for any reason.

Flipping the engine brake to a lower setting is preferable (in my opinion) to constantly switching it on and off.

Normal driving conditions, there isn't really a downside to using the engine brake. If it is loud, obviously turn it off where it would be a nuisance, but otherwise run it as much as you want. On slick roads it can get you in trouble, but otherwise I leave mine on almost all the time on normal paved roadways. In the oilfield there are some bad lease roads that I'll use it less on because of washboard, or other road junk. Or I may need to use the service brakes more because the hills are so steep and the engine brake has a delay before it comes on in full force which can be too late to stop my RPM"s from spiking if I don't help hold it back when it first drops off the top of the hill.

 

They are making a valid point though, even if you don't approve of the way they are saying it. Overly loud pipes and excessive engine braking lead to angry people and more "NO JAKE BRAKES!" signs going up. And that makes life hard on all of us whether we are "real truckers" or not.

 

Running engine brake does "work the engine" and will raise the oil and coolant temperature with extended use but it's no reason to avoid using it.

Also, IMO, many or most of the truck speed limit signs on grades are way outdated and intended for the lack of technology we (most of us) have today. Brakes are much more efficient. And engine brakes are much more prevalent today and more efficient with the higher HP engines.

 

I have always found it humorous some people make comments like your not a true trucker because you do (or not do) this-----. When in reality a true trucker is one that can safely navagate the nations roads pulling 40,000 pounds of freight. Do it legally and maintain a professional attitude. I am 60 years old. My father was a trucker as was most of his friends. To a man they laughed and made fun of what they called idiots that brought every cop in the area's attention to the fact they were there. Then in the 70s more and more signs warning about the unmuffled use of engine brakes being prohibited started going up. Personally I don't give a dang if you use an engine brake when you take a shower. It is no skin off my nose. However I do find it funny as hell when I see some super trucker using an unmuffled jake get stopped by a cop. Trust me it happens a hell of a lot more then you might realise.

 

A lot of older ex drivers do suffer from hearing loss. Just like some old rockers do today from all the amped music. Look at some of the footage of people like the band Pink Floyd today. You will see a lot of hearing aids.

 

Thanks for all the good info dudes!!!