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Semis can't stop like your Little truck.

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Semis can't stop like your Little truck.

Postby good-cause-girl » May 27th, 2017, 3:58 pm

TRUCK.jpg

This should be the image stuck in your head anytime you think about whipping over in front of an 18 wheeler and slamming on your brakes. We can not stop as easy as you think. If you will look close, that used to be a 4 door chevy pick up.


Let us not forget that "if you bought it a truck brought it"..... Give them room. My son and every other trucker out there thank you. No this person did not survive. Please don't be stupid because Darwin is out there waiting for people like this one to add to the list.
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Re: Semis can't stop like your Little truck.

Postby lightspeed » May 27th, 2017, 4:03 pm

Nice sentiment - but you'd be shocked at how fast a rig can stop in normal traffic. Those air brakes be powerful things.

As a professional truck driver, you're always watching for four wheeler goofballs. If you're not, you probably drive an automatic and wear flip flops and drive wearing a hi viz vest and hard hat.
Last edited by lightspeed on May 28th, 2017, 5:06 am, edited 1 time in total.
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Re: Semis can't stop like your Little truck.

Postby Bsuds » May 27th, 2017, 4:31 pm

Well they do it to me all the time when I am driving my F350 and towing a 5th wheel.

I cannot stop as fast!!!

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Re: Semis can't stop like your Little truck.

Postby Bleach » May 27th, 2017, 7:51 pm

Bsuds wrote:Well they do it to me all the time when I am driving my F350 and towing a 5th wheel.

I cannot stop as fast!!!


I have the same problem, the smaller the car, more it ducks in front. That why I have buy a dash cam before my truck is back on the road.

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Re: Semis can't stop like your Little truck.

Postby Dizzy1 » May 27th, 2017, 8:17 pm

Ugh, this picture again. To the OP, please do not misrepresent images with false facts claiming something happened that didn't happen ...

CARROLL COUNTY, Ga. - The Georgia State Patrol say a fatal wreck on Wednesday involved four tractor-trailers and a small pickup truck, killing two people.


The crash happened shortly after 6 p.m. on Interstate 20 eastbound in Carroll County, near Georgia 113.

GSP says a tractor-trailer ran into the back of a second tractor-trailer. That second tractor-trailer then a drove over a silver pickup, crushing it, and ran into a third tractor-trailer. GSP said the third tractor-trailer hit a fourth one.

The driver of the pickup, Larry Donnell Adams, 53, of Benton, Louisiana and the passenger, Peggy O'Neal, 51, of Bossier City, Louisiana were killed in the crash.

The driver of the tractor-trailer that caused the wreck was flown to a nearby hospital. There is no word on the driver’s condition at this point.

Victoria Pope detoured around the wreck on her drive home from work after her friends told her what happened.

"It's like scary, honestly, that it could happen that fast, something like that," Pope said. "And I'm praying."

GSP said charges are pending the completion of their investigation. Troopers have not released the names yet of the people killed in the wreck, pending notification of family members.

The eastbound lanes of the interstate remain closed and there is no word on when they are expected to reopen.


http://www.wsbtv.com/news/local/three-t ... /434341296

Here is a much better representation of what actually happened ...

Image
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Re: Semis can't stop like your Little truck.

Postby dirtybiker » May 27th, 2017, 10:19 pm

OP has the proper sentiment of the very real dangers of snaking a rig.

Even if the effect picture was..off....
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Re: Semis can't stop like your Little truck.

Postby Dizzy1 » May 27th, 2017, 10:45 pm

dirtybiker wrote:OP has the proper sentiment of the very real dangers of snaking a rig.

Even if the effect picture was..off....

I don't disagree with you on that.
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Re: Semis can't stop like your Little truck.

Postby TylerM4 » May 28th, 2017, 7:20 pm

Anyone who looks at that pic and thinks "Truck zipped in front of a rig then nailed the brakes" obviously doesn't have a clue.

Tractor units have bumpers like everyone else, you push the vehicle ahead of you - not drive over it. Unless as per the article - the truck is sandwiched between 2 rigs and it was actually a rig driver who was at fault.

A good sentiment tho I agree. We could simplify to "Don't cut in front of anyone or you could get into a bad accident".

RV, tractor trailer, etc - they can stop ALMOST as quickly as a full size pickup assuming their brakes are in good shape and set correctly. Assuming the driver is paying attention, you may get hit but it's not going to be a violent collision.

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Re: Semis can't stop like your Little truck.

Postby dirtybiker » May 28th, 2017, 9:24 pm

So you say a loaded semi, betwixt 40-63 mt (80-140 thousand lbs) can stop (almost)in the same
space as a f350.
This helps me understand how daft the motoring public is when driving around semi's.

Not a :cuss: ing clue as to how physics works.
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Re: Semis can't stop like your Little truck.

Postby Dizzy1 » May 28th, 2017, 9:39 pm

dirtybiker wrote:So you say a loaded semi, betwixt 40-63 mt (80-140 thousand lbs) can stop (almost)in the same
space as a f350.
This helps me understand how daft the motoring public is when driving around semi's.

Not a :cuss: ing clue as to how physics works.

Um, thats not what he said at all.

He said that the damage to a vehicle if a semi rear ends a vehicle is different then that as if a vehicle is sandwiched between the semi and another object as what happened in the OPs photo.

In comparison, here is what typically happens when a semi rear ends a vehicle that isn't sandwiched into another object ...

https://www.youtube.com/watch?v=WsqKwl8JUy4

So actually, TylerM4s understanding of physics is spot on in his post.
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Re: Semis can't stop like your Little truck.

Postby dirtybiker » May 28th, 2017, 9:44 pm

TylerM4 wrote:
RV, tractor trailer, etc - they can stop ALMOST as quickly as a full size pickup assuming their brakes are in good shape and set correctly. Assuming the driver is paying attention, you may get hit but it's not going to be a violent collision.


Ahem////
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Re: Semis can't stop like your Little truck.

Postby TylerM4 » May 28th, 2017, 10:06 pm

dirtybiker wrote:So you say a loaded semi, betwixt 40-63 mt (80-140 thousand lbs) can stop (almost)in the same
space as a f350.
This helps me understand how daft the motoring public is when driving around semi's.

Not a :cuss: ing clue as to how physics works.


By all means smarty pants. Explain how my physics understanding is lacking! Seriously - use math and facts instead of insults.

Braking is a matter of friction. In other words, your brakes are only as good as friction (traction) available to the vehicle. Once you lock up the tires, it's the friction between the tires(rubber) and the road surface that dictates the braking distance.

So what factors dictate friction? It's simple actually - it's weight and something called "the coefficient of friction". The coefficient of friction is a result of "Rubber against road surface" and doesn't change. It's mostly the same for a pickup and a rig but not exactly the same as the rubber compounds are different.

Long story short the more weight you have, the more friction is produced and it's a linear relationship. As such, you'll find a fully loaded rig and an empty rig have nearly identical stopping distances. It's also why the number of wheels doesn't make a big difference assuming all are braked. It's also why a truck and a rig have similar stopping distances - the factors are the same.

Now the above is hugely simplified because I don't want to write a book. A rig will take longer than a pickup for a number of reasons which is why I said "ALMOST". A modern truck (with antilock brakes, etc) will stop about 20% quicker. "You may get hit, but it won't be a violent collision".

There's no reason a rig couldn't stop SOONER than a pickup. However it would involve expensive antilock braking and stability control systems along with softer tires that wear out too often to be economical.

Here's a simple article to get you started: http://www.understandingforce.com/calcu ... ction.html
Last edited by TylerM4 on May 28th, 2017, 10:36 pm, edited 3 times in total.

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Re: Semis can't stop like your Little truck.

Postby Dizzy1 » May 28th, 2017, 10:10 pm

dirtybiker wrote:
TylerM4 wrote:
RV, tractor trailer, etc - they can stop ALMOST as quickly as a full size pickup assuming their brakes are in good shape and set correctly. Assuming the driver is paying attention, you may get hit but it's not going to be a violent collision.


Ahem////

Sorry, been a long couple of weeks - I was just focusing on the damage aspect of the post which is what I based my post on.
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Re: Semis can't stop like your Little truck.

Postby dirtybiker » May 28th, 2017, 10:48 pm

And the heat generated from brake lining to drum when put to work against the forces of weight vs speed
greatly reduces it impact on stopping power.

there is more to it than just rubber meets road.

I've said it for years, "even a physics professor will pull out in front of
a loaded super b that is at speed."
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Re: Semis can't stop like your Little truck.

Postby Bsuds » May 29th, 2017, 4:28 am

https://www.udot.utah.gov/trucksmart/mo ... distances/

This one shows it very well and I have a very hard time believing a semi can stop "almost" as fast as a pickup truck.
As well the semi will take much farther to stop if the brakes are hot.

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