Jake brake in pre-emission engines

My pre-emission 12.7 detroit will hold 80,000 lb on a 6% grade at ~25mph using no service brakes.

I briefly drove a 6nz that would hold ~30mph @ 6%.

For comparison, both the maxxforce 13 & the dd15 that I drove as a company driver would hold that same load at 30-35mph.

 

Some CAT's have a Pac brake and some have a Jacobs brake. Mine has a Pac brake and does about as double yellow described. I've never driven one so I don't know but I've heard Jacobs does a better job braking.

The turbo also has an effect on how effective braking is with either pac brake or jake. Experts would have to explain why but guys with big power who put big turbos on their motors many times complain about poor jake braking.

 

The turbo adds boost with the jake on, more air in the cylinders
Equals more compression, better braking.
Running the overhead can help the jakes work better.

 

Ran a 97 or 98 Mack, that thing's Jake was basically just a noisemaker.

When I went from my 5EK Cat to my 6NZ Cat, I noticed a little bit stronger of a Jake I think, but still not near as strong as the old man's MXS Cat.

Old mechanical Cummins's will pass a mechanical Cat going down hill all day every day.

 

ISX15 jake is pretty strong, 40-43 mph on 6% grades with no service brake. Fully loaded