Brakes Locked up on Freightliner While Bobtailing?

I can't see how that happen either. If the driver did lockup the brakes to avoid something the ABS should have stopped the front brakes from locking up. If the truck had automatic emergency braking the ABS still shouldn't let the brakes lock up. It was a new truck basically. So is it possible the ABS was not working and had dash warning that driver did not say anything about. Then the driver hit brakes hard and they locked up. It could have been anything. Maybe something in steering linkage broke like some else said and

 

Maybe the foot valve went bonkers and put full psi on fronts and nothing on rears? Abs valves will not be able to keep 120 psi of pressure from locking the brakes.

 

Had to be a wild ride for your driver. There is no way to control that. Those steers are going where they want and taking you with them.
Back in the ancient times that is why we did not have steer axle brakes on anything with 3 axle or more.

 

Look the truck over real good yourself if you can. You mentioned it was a rental unit so hopefully they will allow you to do that without hassle. Check the steering out from head to toe and make sure it didn't fail like has been mentioned already. Navistar and Freightliner both have had recalls on steering components.
Not sure what year you guys had but both our ‘99 and ‘03 Freightliner’s had a recall on the rod that goes from the brake pedal through the firewall to the foot valve for breakage.

 

Does this truck have some kind of collision avoidance or stability system on it?

Reason I ask is that a truck with only ABS has no way of applying any brakes as brakes are solely 100% from the treadle valve or trailer spike. ABS just modulates the air supplied to the brakes from those valves.

I would have to assume that stability or collision mitigation systems have seperate air feeds to allow the system to apply brakes independently. ABS should still be modulating brake pressures to prevent a wheel lockup.

 

Was that one of the trucks that had the recall for the tie rod ends that could fail/break with no warning???? I know that Frieghtliner Cascadias had that issue around the year of your truck. Not sure if or how this could cause what you describe, but might be worth looking into.

 

Also even had a air valve switch on the dash that shut off air supply to the front brakes. Think above the switch-valve it said something like " for use on slippery roads"? IMO this accident had more to do with than the front brakes locking up.

 

Man thats old school brakes that had the blue knob or the switch to reduce front braking force!!!!