Question About Jake Brakes

[Rookie McRookerson]

During my OTR training, my trainer told me to turn off the Jake Brake switch when going uphill. He said that having the switch in the on position effected the horsepower of the engine.

I did as directed. But, it didn't make any sense to me.

Is this true?

[terrylamar]

During my OTR training, my trainer told me to turn off the Jake Brake switch when going uphill. He said that having the switch in the on position effected the horsepower of the engine.

I did as directed. But, it didn't make any sense to me.

Is this true?

I'm not a mechanic, but I don't see how with one exception. The Jake Brake is not functional when the clutch is pushed in. So when you down shift it won't make a difference, unless you have a splitter, as in 13 or 18 speeds. I forget to turn mine off until the first time I split and I always wonder what's up with the engine.

[Rookie McRookerson]

Ahhhh, I guess I should add, I drive an auto-shift.

[ben45750]

During my OTR training, my trainer told me to turn off the Jake Brake switch when going uphill. He said that having the switch in the on position effected the horsepower of the engine.

I did as directed. But, it didn't make any sense to me.

Is this true?

Nope, doesn't make any sense at all.

The only way a Jake brake is going to come on is to let off the fuel. Why would you let up off the fuel while going up a hill? The Jake brake is turned on and off by a electrical switch so there is nothing mechanical in the switch (being a Jake brake is mechanical), thus making no difference if the switch is on or off when the Jake brake is not activated.

I might be wrong? But I can't see how there would be a difference?

You were told a load of poo.

[Roadhog]

Only time I turn my Jake off is in backup traffic...or when I enter areas other Truckers are likely sleeping.

First time I heard of something like this...and now I guess I've finally heard it all. .....er...naw...plenty more BS where that came from.

Tell this Trainer to become a member of CAD. He could use our help. :P

[Jackrabbit379]

During my OTR training, my trainer told me to turn off the Jake Brake switch when going uphill. He said that having the switch in the on position effected the horsepower of the engine.

I did as directed. But, it didn't make any sense to me.

Is this true?

Bull butter! Jake brakes work when you let off the throttle. As long as you have your foot into it, they wont come on. As soon as you let off of it, they come on. Your trainer is full of beans. He needs to be trained. :P

[Kranky]

During my OTR training, my trainer told me to turn off the Jake Brake switch when going uphill. He said that having the switch in the on position effected the horsepower of the engine.

Your trainer if F.O.S.

[TK THE TRUCKER]

I agree with everyone else. Having the jake switch on or off shouldn't matter. However, there can be different horsepower settings between the cruise control and the pedal. It depends on the truck and whoever programmed it. Some are 470 on the cruise and 430 on the pedal, or 430 on the cruise and 370 on the pedal, etc. It's power ratings depends on the the engine make and whoever in in control of the ECM parameters. Maybe this is what your trainer meant ? 8) 8)

[flood]

just had the wife try it nothing changed still 43mph, and yes it's an auto-shift

a side note on our 05 & 06 freightliner with detroit power the jakes were set to come on when you hit the brake's, :shock: on both truck thats the way the ecm was set so we had to have then plug in the laptop to change it

[PackRatTDI]

Ahhhh, I guess I should add, I drive an auto-shift.

The engine brake works in conjuction with the autoshift transmission to make quicker shifts, so it's essentially always "on".

[flood]

Ahhhh, I guess I should add, I drive an auto-shift.

The engine brake works in conjuction with the autoshift transmission to make quicker shifts, so it's essentially always "on".

true the trans will over ride the switch for faster upshifting (when needed)
but if the switch is off that is the only way thay will come on

[ssoutlaw]

Full of shi^, plain and simple....lol

[Rookie McRookerson]

Thanks for all the replies. I thought my trainer was "FOS" but was in no position to say so!

I guess I'll stop flippiing the switch off when climbing hills!

[Windwalker]

During my OTR training, my trainer told me to turn off the Jake Brake switch when going uphill. He said that having the switch in the on position effected the horsepower of the engine.

I did as directed. But, it didn't make any sense to me.

Is this true?

I've also had a couple of trainees that said the instructor told them you could use the "clutch-brake" to help you stop the truck.

If you understand a wiring diagram, look at the wiring connections for the jake brake. The switch that turns it on and off goes in series with the switches on the clutch pedel and throttle. If you're going uphill, you have the throttle engaged, right? With the throttle engaged, the switch on the throttle is open and the jake is disabled. That switch does almost exactly the same thing as the switch on the dash. BUT... the switches on the throttle and clutch automatically engage the jake when either pedel is released. In a manual shift, this could (and often does) reduce the rpm of the engine faster than you can react with the shifting lever.

On an auto-shift, (I have never driven one), I would expect to find that the computer that does all the work shifting, would also control the jake.

On my own truck, I never turn if off unless I'm going through a town with a restriction, or after 8PM if I'm near a residential area. Parents tend to get a bit irate if a loud noise, like a jake brake, wakes up an infant they've been trying to get to sleep for several hours. It's a matter of courtesy.

I know of NO instance that it effects the operation other than engine RPM during shifting, if you float the clutch. It's rather like the guy that tried to tell my wife that if she plays "country-western music" on the stereo, it will degrade the speakers and stereo components. My vote says it's a bunch of HOG-WASH.