What it takes to stop a train from 45 mph

"Dusty Ventures" (dustyventures)
11/18/2019 at 13:31 • Filed to: None

Trains have a reputation for being big, heavy, and hard to stop. But just how much does it take to stop a fully loaded freight train?

This UP double stack train was put into full emergency stop when an air line ruptured. On a standard train all the cars are connected on a single air line that operates the brakes. A compressor in the engine charges the line, increasing pressure in the line decreases pressure on the brakes. A fully charged (brakes fully off) line is in the 70-90 psi range. If this brake line separates the loss of pressure automatically applies full braking force on each car on the train.
TL;DR: separating an air line results in the hardest a train can brake.

Now for some numbers:

The first number requires no math. It took one minute and four seconds for this train to come to a complete stop.

Next, establishing the speed. The !!!error: Indecipherable SUB-paragraph formatting!!! in front are 71 feet each. it took about 3.25 seconds for all three to pass the right edge of the frame. That gives us a speed of 65.5 feet per second, or 44.7 mph.

And lastly, distance. Rail manufacturer !!!error: Indecipherable SUB-paragraph formatting!!! puts their double stack cars at 76.75 feet long. 39 cars pass by from the time of brake application to the time the train finally stops. That gives a stopping distance of 2,993 feet. More than half a mile.

So, put simply, a large freight train like this, under maximum brakes, still requires over a minute and roughly 3,000 feet to come to a stop from 45 mph

DISCUSSION (23)

For Sweden > Dusty Ventures
11/18/2019 at 13:33

Sure but what if the brakes were slotted

CarsofFortLangley - Oppo Forever > For Sweden
11/18/2019 at 13:35

Drilled and slotted. COOLING BRO, DON’T WANT MY BRAKES OVERHEATING.

Also, red calipers = +15% braking force.

Get on board train manufacturers

f86sabre > For Sweden
11/18/2019 at 13:36

Drilled?

davesaddiction @ opposite-lock.com > Dusty Ventures
11/18/2019 at 13:44

Inertia’s a bitch.

LongbowMkII > Dusty Ventures
11/18/2019 at 13:50

Surprisingly quickly all things considered. I wonder how much heat was generated, whew

facw > davesaddiction @ opposite-lock.com
11/18/2019 at 13:51

Nibby > Dusty Ventures
11/18/2019 at 13:54

put a person at 3,000 feet from where it starts braking

jimz > Dusty Ventures
11/18/2019 at 13:57

air brakes on heavy trucks work similarly. Amusingly, I found out after a ride in an F-750 that auto transmissions in these things don’t have a “Park” selection. They just put it in neutral and de-pressurize the brake actuators.

This is what we'll show whenever you publish anything on Kinja: > Dusty Ventures
11/18/2019 at 14:02

Kinja'd!!!

Manwich - now Keto-Friendly > Dusty Ventures
11/18/2019 at 14:08

So Consumer Reports would rate their braking as ‘poor’, eh?

TheBloody, Oppositelock lives on in our shitposts. > Dusty Ventures
11/18/2019 at 14:17

I remember one time coming home from work the train I was on hit a trespasser (read: dude jumped in front of the train) and it took us about 40 seconds to come to a stop from about 70mph.

Darkbrador > Dusty Ventures
11/18/2019 at 14:54

Were the locomotive still pulling the train while the cars were at full braking, or is there a system to get the engines to idle if a brake line ruptures ? So many questions ...

benn454 > facw
11/18/2019 at 14:57

Best. Overheard Citadel conversation. Ever.

benn454 > jimz
11/18/2019 at 14:58

Waiting for the low air pressure buzzer to finally shut up at dawn is the fucking WORST.

wafflesnfalafel > Dusty Ventures
11/18/2019 at 15:42

yup, Newton’s first law...

HammerheadFistpunch > For Sweden
11/18/2019 at 16:25

Cryo or get out.

HammerheadFistpunch > jimz
11/18/2019 at 16:30

WE nearly missed the last ferry back to the mainland in Norway once because an air line rupture. Thats when I discovered the way air brakes worked. Then my wife and I both had a learn more when she got her CDL with airbrake endorsement.

Where have all the lightweights gone? > Dusty Ventures
11/18/2019 at 16:32

The only thing that sucks worse than a disconnected brake hose? Being on this crew and having to walk the entire train and inspect every single connection.

Whoever is stuck at that crossing is either turning around or will be stuck there for a couple hours.

Dusty Ventures > Where have all the lightweights gone?
11/18/2019 at 16:50

Yeah, you can see the worker walking the train in the video. Looks like he had to go at least 3/4 mile

Dusty Ventures > benn454
11/18/2019 at 16:53

Which is saying something since there's some absolute gold in those background conversations.

WilliamsSW > Dusty Ventures
11/18/2019 at 16:56

Bonus question - where are the brake “ drums” on a train?

A: they are the wheels. The air pressure drop applies the brake shoes directly to the wheel tread. It’s entirely possible for wheel tread temps to reach 800+ degrees. I have seen wheel treads turn blue from heat on the Sierra Nevada grade descending into Sacramento.

Source - I was a field engineer for a maker of RR wheels and brake shoes for 8 years

benn454 > Dusty Ventures
11/18/2019 at 17:01

My other favorite is when it slowly dawns on the human, turian, and salarian that maybe the asari aren't actually the sexy space babes we see them as. (insert Keanuwhoa.gif)

ttyymmnn > Dusty Ventures
11/18/2019 at 17:40

I’d also be interested to know how long it takes for a train like that to attain 45 mph.