How Dangerous Is A Jake Brake In Poor Road Conditions?

Some really good technical discussion here I appreciate everyone’s answers. And the clarification

G-Town, I’m curious about the cruise in the mountains. My OTR trainer said not to use cruise in the mountains as it won’t be able to keep up with the inclines. He seemed to indicate it would just kick itself off. Could be a just the way the company has them set up as Roehl apparently stands for Rolls Over Every Hill Last. I like the idea of setting the cruise at a lower speed on the downhill. I always seem to need to slow it down manually before the Jake kicks in automatically.

Bill...I am in and around the Poconos constantly, and swear by this driving technique (as described in my last reply). Perhaps your trainer wants you to learn how-to control the truck in the mountains without cruise (which is a really good idea). That said, based on what you described, I'll take a SWAG..."are you in an International?"

Occasionally I'll be in an Int. or KW, but 98% of the time, Cascadia. The delay? There isn't one in the Cascadia. That said, if you begin to reduce the speed setting 1-2 seconds before you begin to descend, it will hold the hill way better. If it's slipping, reduce the speed further.

But no matter what, if your trainer insists on running the hills and mountains as you described, please respect his wishes.

Thanks for the speedy reply. I’m out of training and out solo now so, I’ll give it a shot on my next run out there. I’m in a Cascadia now and was in training. My trainer wouldn’t let me use cruise for the first few days so I could get the control down. We were way past that when he made the comment. He had either had a bad experience or had faulty information. I’ll give it a try and see what happens. The added control on the downhill will be a big win.

Funny, the original question was about poor conditions and I ended up learning something about driving mountains in good condition as well.

Thanks for your help!

My 2017 kw adaptive cruise will not kick on the engine break downhill it does when i get to close to a car and my my following diatance gets smaller. It actually just lets off the throttle if its a slower vehicle moving at a similiar speed but if i get cut off it will use the Jakes. Might be a different system then you guys have though. It also downshifts way too slow while climbing even slower than when not using it on my auto but i can manually downshift in cruise.

My 2017 kw adaptive cruise will not kick on the engine break downhill

If you get going fast enough it will. It also depends on the speed it was set at prior to the descent.

I saw G-Towns driving technique on the ride along. Its pretty amazing how the truck can be controlled without using the brake or accelerator pedal much. He controlled the speed on the highway 100% with the cruise buttons on steering wheel and column shift during the 1st half of day in dry conditions. Granted it was a Sunday and I’m sure the light traffic helped. With more traffic and numb skulls on the road I figure the service brake would be needed more. 2nd half of day it started raining and it was conventional pedal driving back to DC

Delco Dave remembers...

I saw G-Towns driving technique on the ride along. Its pretty amazing how the truck can be controlled without using the brake or accelerator pedal much. He controlled the speed on the highway 100% with the cruise buttons on steering wheel and column shift during the 1st half of day in dry conditions. Granted it was a Sunday and I’m sure the light traffic helped. With more traffic and numb skulls on the road I figure the service brake would be needed more. 2nd half of day it started raining and it was conventional pedal driving back to DC

Thanks Dave. I agree; these trucks are amazing, especially considering we scaled-out at 78+ k when leaving the DC that day.

You bring up a great point, cancel cruise control in moderate to heavy traffic. You now understand my desire to run over the weekend. No traffic!

Well...that is until entering North Jersey. LOL!

Midnight Fox inquired:

I'd read deep searching on here that a driver should always put it in manual mode when going down steeper grades. I'd also read the on-board computers are able to regulate the engine braking by the weight of the load, the present grade, and even terrain maps (or at least Turtle had mentioned this i re some of the trucks at Prime).

Does it work like that shifting without the jake brake too, if it's an automatic and the manual mode has been disabled?

"Always?" If it's dry, not necessary to invoke manual mode, bypassing the auto-shift operation.

In the newer "auto-shift" trucks, cruise control and the engine brake (Jake) are electronically linked. Called "Drive Wyze" (on Swift equipment), this control is programmable and may vary slightly from truck to truck. Most of the major carrier have this type of control system on their newer, auto-shift trucks.

At a high level it works like so; set cruise for 65 mph and the system will maintain that speed invoking the engine brake as the speed approaches 69, such as it occurs descending a steep grade. As a rule, when I am running in the mountainous terrain of North Eastern PA & NJ (Interstates 80, 81, 84, 78, PA-TP NE Extension, etc), as I approach a downhill grade I will reduce the speed setting to about 60-62 mph (depending on grade steepness) so I can maintain control descending the hill. The system will invoke the Jake in whatever intensity required (low, med. or high) to control the truck, holding no more than 4 mph above the set speed. As the terrain flattens out, I'll resume the cruise setting to 65. It is very, very rare that I will need to assist with the service brake/ disabling cruise. As such, when cruise is set to "off" or "cancelled", manual application of the engine brake is required.

All of the above is NOT applicable in wet or snowy conditions.

I’ll second this. The cruise works great, holds it at the correct speed.

Occasionally I’ll chicken out and brake and then turn the cruise back on, but not because it is going too fast, because the rpms climb so high I’m afraid it will blow the engine. Usually not a problem unless I’m loaded right at max weight though.

I go down the 6 mile 6 percent grade on I 90 at Blandford MA weekly, the automatic holds it back like magic.

Went down this in the snow today. First time I have ever been scared in my first year. The roads were slick.

Used 7th gear in manual mode and brakes gently and had no problems.

Forgot to add the picture. Imagine trying to read that sign while moving. Lol

Question - the down shifting in automatics yall keep talking about, is it the same as a 10 speed? Rev to rpm the down shift? How is this accomplished without a clutch? Never driven the autos before just stick....was wondering