Braking with no engine power

I’m trying to get a sense of braking ability in the event of engine failure on the freeway or a mountain pass (especially a steep downhill grade). I assume the power braking system will not be working. These trucks (like any) are obviously very heavy. Can the brakes be fully applied in this scenario, or will there be pressure build up that makes this ineffective? Is the parking brake an option for further braking ability? The recall mentions loss of motive power being a safety issue, but doesn’t mention braking. This leads me to assume this will still be fully possible, just with more force being needed.

 

The parking brake will probably lock up the rear tires, be ready to drift….
Unless more than likely there is a safety mechanism so it will not engage above a certain speed. Only one way to find out!

 

There will be vacuum in the brake booster, enough for a braking event, or two.

 

If none of the above happens, then pump pump pump pump the brake pedal….unless brake actuation is electronic, now, too (not talking about the P brake).

 

This. I've had it happen several times on older vehicles and you get one good solid brake application from the vacuum left in the booster, maybe half a second brake application, so make it a good one. If you run out of vacuum, you need to try and Fred-Flintstone that brake pedal through the floor. It will work, but you may bend the steering wheel pulling up on it for leverage. I may or may not have done that in another vehicle..

 

Stick her in 4wd (if ya have it) and force the parking brake.

 

Yikes, drifting or Fred Flintstone’ing sounds fun but what about the trailer. I guess one could use the trailer brakes to slow down if you can grab the lever fast enough.

 

If the engine fails - which I believe is the case being discussed - the electrical system would remain intact and the trailer brakes would still work as they are electric. So, yes, you can use the trailer brakes to slow down. They will still engage when you use the vehicle brakes for the one or two applications that you will get. Manually actuating the trailer brakes would be a good strategy once the vacuum in the booster has dissipated, but you would need to be carefully not to lock them up. If they are setup properly to begin with, that should be less likely to happen but still possible.