Does gear limit use brakes?

[blakei]

A few times I’ve been going slowly down a slope, like a long driveway that’s a few hundred yards long, and I’ve set gear limit to 1.

The engine will rev to about 4000 rpm, then somehow slow back down to 2500 rpm or so, then go back up to 4000 rpm, and then cycle again.

I’m not pressing the brake pedal, but I don’t understand how the truck and engine slow on their own. Does the compression somehow change? In other (manual) vehicles I’ve had they normally stay at an elevated rpm if the grade doesn’t change.

I’m asking as I rely on gear limit in 4 or 5 to help control my speed when towing our 28’ trailer. But if the truck is somehow using the brakes to keep the rpms down, then I may as well use the brakes myself, and now I’ll be worried about brake fade.

Anybody experience this or know how gear limit works?


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[Gitter]

A few times I’ve been going slowly down a slope, like a long driveway that’s a few hundred yards long, and I’ve set gear limit to 1.

The engine will rev to about 4000 rpm, then somehow slow back down to 2500 rpm or so, then go back up to 4000 rpm, and then cycle again.

I’m not pressing the brake pedal, but I don’t understand how the truck and engine slow on their own. Does the compression somehow change? In other (manual) vehicles I’ve had they normally stay at an elevated rpm if the grade doesn’t change.

I’m asking as I rely on gear limit in 4 or 5 to help control my speed when towing our 28’ trailer. But if the truck is somehow using the brakes to keep the rpms down, then I may as well use the brakes myself, and now I’ll be worried about brake fade.

Anybody experience this or know how gear limit works?


Sent from my iPhone using Tapatalk

I'm not sure about the gear limiter, but when I tow, I put it in tow/haul mode. When going down hills or steep grades, it will hold your gear after the first brake application so that the engine is maintaining your decent. Once it starts that engine braking process, it doesn't drop the RPM like you are describing.

 

[Trooper4]

As far as I can tell, the only time brakes are automatically applied is when using cruise control. Gear limiter will let the engine over-rev if the load and grade are steep enough. When towing I use cruise and have the etorque, and notice that it uses resistance breaking to reduce break usage. but still uses the breaks if needed to hold speed.

 

[silver billet]

Manuals will slow down too if you downshift, that's how they often get away with longer brake intervals. So no, using the gear limiter does not activate the brake pads, it's just standard engine braking.