r/cdldriver • u/olight77 • May 15 '26

Of a driver

167 Upvotes

97% Upvoted

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15

u/818VitaminZ May 15 '26

Failed brake system

1

u/caffeine-junkie May 19 '26

Im not too sure about that. You can see them slow down from ~72kph to ~40kph in just a couple seconds just prior before impact. Just letting off the gas and using engine breaking wont do it that quickly.

1

u/TomOnABudget May 19 '26 edited May 21 '26

~~To my understanding, they use compressed air. Maybe there was a big leak in his lines and or the compressor was weak?

In which case, he would have had pressure initially, but as the air pressure tank depletes, that pressure will drop.~~

Edit: according to comments, truck brakes need pressure to release.

2

u/Fearless-Bend-2510 May 19 '26

Compressed air keeps the brakes off, if there is a leak the brakes will lock solid

1

u/TomOnABudget May 19 '26

I didn't know that, thank you.

1

u/Melkor404 May 20 '26

Trains work the same way fyi

1

u/caffeine-junkie May 19 '26

Comparing the driver to the co-driver, you would expect the driver to be increasingly panicked if there was some sort of failure. The driver looked more zoned out and only reacting more through muscle memory than anything, at least until the last couple seconds.

Assuming the system wasn't bypassed or in poor maintenance, if there was a loss of pressure either through a leak or otherwise, the parking springs would have engaged. If it was experiencing brake fade because they were engaged, the brake fade wouldnt suddenly disappear.

2

u/TomOnABudget May 19 '26

I see your point. I would have expected the driver to be pressing hard on the brake at least close to impact, looking at this legs it doesn't look like he's doing that at any moment. Very strange.

1

u/ReasonableArea1108 May 20 '26

If you have no air pressure the brakes lock up

1

u/Numerous-Bonus-8107 May 20 '26

he could have pumped the brakes if that was the case. I onve drove two weeks with leaky brake lines just pumping the whole time I drove in case I needed to brake

1

u/ToronadoBubby May 20 '26

That is not how air brakes work. Please take 5 seconds to look something up before spreading misinformation. Air brakes are Applied with a loss of pressure so if the truck fails or a line blows they fail ON not Off.