Well it’s been a lively day here. South of town there’s a gravel pit and after a climb into the valley, it’s about a 3-4% downhill grade from there through town. Highway 36 is also our Main Street. A semi lost it’s brakes just as he was coming into the South end of town and came flying down Main Street, hitting 27 cars and ending up crashing into the Ford Dealership. Dude did a pretty decent job of steering clear of traffic. Several people injured but nobody killed.



[video:youtube]https://youtube.com/shorts/IKXhMtesrBo?si=MhUZtV3o2ZY1gdUX[/video]

Someone missed a brake check this morning. Modern semi’s don’t loose brakes unless they are miss adjusted.

LOL huh?

Carrying 30,000 pounds of bannas?

The guy running that dash cam is a top notch defensive driver.

Could the guy have shut off the engine?

Obviously not a trucker here,

A lot of people don’t think about it this way, but there are truckers who are heroes. Machines fail and the trucker often keeps people from getting hurt, often to their own demise.

Lucky.

Many years ago I was driving north bound coming down the Siskiyou Summit on I-5 and moved over to let a semi fly by with fire coming out of his front wheels.

3-4% grade is no big deal. Failure on all parts.

No Jake brake?

Lose the engine, lose the air compressor, lose the air brakes. Every semi I've driven had an emergency brake lever next to the steering wheel. Pull it and everything locks up. I haven't driven one in 25 years, though, so I can hardly say what's in a modern tractor.

I wondered the same. They’re illegal in town but if you’re out of options who cares. I’m sure the Highway Patrol and UDOT will have a lot to say about it. Wondering if he got the trans in neutral and couldn’t get it back in gear for some reason or snapped a U joint and threw the driveshaft; damaging the air lines.




Definitely tore things up. Kilgore, well their insurance, is going to be writing quite the check. We’re up to 33 vehicles now.

A fellow Harry Chapin fan, I see.

Crystallized the brakes ?
If it had been an air line issue brakes would have locked up once pressure dropped to a certain point
Kenneth

That wouln't do much, but there is a large, yellow, diamond shaped, button on the dash that should have stopped the truck by locking up all the brakes on all the wheels a long way back up the hill.

The guy's pulling doubles, likely 100,000 pounds. The Jake brake isn't slowing that down.

Driver error.

You can see the smoke pouring out of the truck.
When facing a long downhill, the driver has to downshift prior to hitting the downhill. In this case he probably wanted 6th gear. You let the transmission keep you slow on the hill.

If you leave it in tenth gear, the truck will go too fast, and you have to try to slow down with the brakes. The brakes will catch fire, and the brakes will fail, and then, you have a runaway truck.

Lotta misunderstandings here.

Properly adjusted brakes are a huge deal, but modern trucks can certainly lose
brakes even if they started out adjusted properly. Losing brakes is an affect of getting hot, not too much slack. Unevenly adjusted brakes can accelerate problems due to individual brakes heating faster, then failing. Leaving more burden to the remaining brakes.


Shutting a diesel off does nothing.
The hold back effect of a gas engine is pumping loss.
It's the effort of drawing vacuum, caused by closed throttle plates.
Diesels don't have throttle plates. The throttle directly controls fuel, not air movement.



The brake lever by the steering wheel (looks a bit like an automatic gear selector)
does not "lock everything up". It's simply a hand brake that controls the trailer brakes
only. On straight trucks it controls the drives and any lift axles.
It uses the same air as the foot pedal, in the same way. Except it only actuates the trailer brakes.
Mostly, it's used to lock the trailer axles to slide tandems or 5th wheels.

A lot of company spec trucks don't have them. Guys use them instead of the service brakes. Over taxing the trailer brakes and ruining them.(using them for anything other than sliding stuff is controversial)





As to the brakes locking due to low air?
Pulling the yellow button?

Both are the same thing, one automatic, one driver activated.
Usually, if they automatically deploy, the button pop's out. Sometimes, there is a small psi range where the brakes apply but the button doesn't pop.

That braking system is simple spring powered.
Pushing the yellow button supplies air to an actuator that compresses the springs and
releases the brakes. If the button is pulled or air pressure lost, the actuator disengages and strong springs apply the same brakes normally used.
But not with anything like the power of the air system. A heavy truck rolling at some speed, downhill, is very likely to NOT be stopped by the spring brakes.


Jake brakes can and do fail, not often.
Transmissions can jump out of gear. On old mechanical engines, that usually shut the engine off. Losing the air compressor and power steering. There is no way to get back in gear until the engine is running. If the truck accelerates to a speed higher than
It's governed at, it's impossible to get a gear even if the engine starts.


There are numerous possibilities here, the service glad hand popping off is certainly a possibility.


One thing I will bet the farm on.
It's not one issue.
Accidents are almost never a single failure.

Usually in something like this you will find,
Speed
Brake Maintenance
Brake adjustment
Other mechanical failure
Air loss (maybe tied to other causes, especially maintenence)
Over loaded
To name a few.


By the time DOT is done, they will have a list.



If he was overloaded, the quarry may well be involved.
The one I hauled out of refused to let us leave heavy. Following a wrongful death lawsuit that they were involved in. Selling an extra ton of stone cost them dearly.

Yeah, he could - then he would have been without both brakes AND power steering.

All of this. That's a good comprehensive write up.

If I were the speculating type, I would add the two most likely causes were an inexperienced driver not knowing how to come down a hill, or an older driver who's come down that hill a "thousand times with no problem", but doesn't realize each time your brakes are a little more worn out. Eventually, they're too worn out to let you go down again.

First question I'd ask is which Mexican trucking company does that rig belong to.

Nope, not likely.

The power steering pump is run, by gear, off the accessory drive.
Unless the truck was a torque convertor automatic, if it is in gear the power
steering pump would pump.

Unfortunately, I'm not sure about the compressor.
It too is gear driven by the accessory drive or fuel pump.
But there is a pressure switch controlling the valves to allow it to pump.
I can't remember if there is electricity required or not. (Never worked on them, really)
The compressor would turn, but may not pump.


A drive train failure is possible.
If there was a free wheeling situation of any kind, the above is all wrong.



Not gonna do it, no war stories.
However...🙂the longest and scariest event in my trucking career involved a Mack
Tri-axle, loaded, a long downhill on a 4-lane at top speed, the back half of a 13-speed
jumping out of gear, and the Jake brake killing the engine.
Brakes weren't the issue, steering was.

Hint, if ever in that situation.
DO NOT START THE ENGINE IF YOU ARE PULLING ON THE WHEEL TO
KEEP IT ON THE ROAD!!!

I had a jake quit on a steep down hill once. I was luckily plugged into a low gear but ran through that pretty quickly. I wouldn't want to be pulling a trailer/s in traffic when that happened.

When I was welding on the bridge at white bird Idaho we had signal people set up to alert the flaggers and staff to out of control trucks. It happened a couple times in the job....scary stuff.

It’s does take very far down hill to burn the brakes up on a semi. Lose a gear or clutch and stuff happens quickly. Happened to me as I was downshifting to do down about a two mile hill. Clutch cable broke with the clutch disengaged. No link between engine and driveline. Tour busses were going in and out of a tourist site to view the Alaska pipeline. I was terrified of killing a bus load of people but luckily they must have heard the horn blowing and none pulled out. Edk

Crazy...........many lucky people fur sure

Commercial vehicle safety inspections stop too ?

As did the personal vehicles a few yrs ago.......

https://www.ksl.com/article/5077612...d-in-tooele-after-semitruck-loses-brakes

With a 3 axle lead and a 4 axle pup, he was likely grossing 129,000 lbs - stop and think about that if you are used to driving a 4000 lb car or 7000lb pick up. Keep that in mind the next time you think you have the right to jump in front of a truck.
You don't like being behind a truck when the light turns green, why would you jump in front of one when the light turns yellow/red?? Just because there are 3 cars in your lane and 1 car in my lane?? It takes me as long to stop as it does to get up to speed - I need that braking distance, and by you jumping in front of me, to get 2 car lengths further down the road, might be the last thing you do.

Dillon cleared most everything up. At least one mechanical failure, probably more.

Most big rig crashes on downhills are because the driver failed to downshift to a low enough gear, and to let the transmission slow the vehicle. Instead he relied on the brakes and the brakes can't take it and they will catch fire.

Look at the smoke billowing from under this truck, his brakes are smoking.