Topic: Scary stuff, transport loses wheels

[Ex-airbalancer]

Do u think volvo roofs wiuld have been able to withstand this impact?

They do test their roofs and a pillars extensively...

I would think not
Volvo would probably testing for rollover  not a thin 100 lb wheel hitting it at over 200 kph

...they roll their cars on their roofs on purpose and drop the whole car upside down on their a pillars......   and do   Moose hit tests..     and mythbuster proved that object going one way at one speed and another object going the otherway at the same speed does not make the impact twice as powerful.

That may be true but saying over 200 kph sounds better

Also the hood is caved in , then the window shield , so who really knows how it hit the SUV

All I know I would not want to try it in a Volvo to find out the answer

[EV Dan]

Looks like lug nuts were loose and the entire weight was applied to the lug bolts breaking them right off. I wonder if a self driving car in some distant future will be able to avoid such a thing, coz not even every driver can react quickly and appropriately to something like this, even if he/she is not texting, eating or sipping coffee.

[tortoise]

and mythbuster proved that object going one way at one speed and another object going the otherway at the same speed does not make the impact twice as powerful.

No way is that correct.

Pretty sure hitting a car head on is the same as crashing into a wall. 

You can definitely double the velocity for a tire heading your way.

[Noto]

Not sure what style of wheel this situation was. There is this type of wheel that commonly develops cracks around the lug/hub bore. It's extremely hard to notice and requires a careful look. This style of wheel  was popular in the 80's to mid 90's called a non piloted budd wheel. This type was a real pain, it had two sets of studs, one to hold the inner wheel and another set to hold the outer wheel with lug nuts. These types were prone to crack stress and stud failure (hence why they're not used anymore) New style budd wheels have one stud (much larger) and one wheel nut. as most cars use.

 This is the old, dangerous two stud system

The OP link above shows the officers hauling the wheels into a van, and already inside said van is a wheel hub.  I suspect you're on to something.  What a revelation!

[Fobroader]

What was inside the van was the brake drum......which is a couple of hundred pound piece of metal.

[Noto]

What was inside the van was the brake drum......which is a couple of hundred pound piece of metal.

I tried...

[tortoise]

[PJungnitsch]

Random tragedy...any idea why regular car wheels don't go ballistic...SHEAR FORCES on big vehicles? lack of maintenance! crappy parts being used?............

If you notice it is always the trailer wheels that go flying off, not any part of the tractor tandems.

Two reasons:

1. Tractors are invariably better maintained than trailers.

2. But by far the more significant reason is that when turning, sometimes while going forward, but mostly and especially when backing up and turning at the same time the back tandems often twist in the same place as the truck pivot's around e.g. to back up into a loading dock. That places tremendous shear forces on those back wheels as they rotate while in place. When new they can withstand that force but as they get older and with exposure to salt and corrosion they can snap off easily, anywhere, including on the highway.

To get around this problem, they will have to change the law and make it mandatory to replace the back trailer tandems of every trailer say every 3-5 years. It will be expensive but the only way I see to make this problem go away. It is physically impossible to evaluate how much stress a wheel assembly will take before it snaps in any kind of daily inspection. I doubt whether even a qualified mechanic will be able to definitely certify a wheel assembly as road worthy based on a visual inspection.

Sounds plausible.

Don't the Europeans use pivot plates on some of the trailer axles for this reason?

Europeans have a lot of body jobs with trailers, vs the semi trailer setups preferred in NA.

I always thought the reason was for greater maneuverability when navigating narrow windy streets, at the cost of being ungodly difficult to backup because of the double pivot.

[quadzilla]

I heard that there were 127 flying tires in 2015. Wow.

[blur911]

and mythbuster proved that object going one way at one speed and another object going the otherway at the same speed does not make the impact twice as powerful.

No way is that correct.

Pretty sure hitting a car head on is the same as crashing into a wall. 

You can definitely double the velocity for a tire heading your way.

No, you can't just double the velocity of the wheel, it's not the same kinetic energy when 2 things each going 100kph hit together as when one object is going 200kph, it's only half the energy as the single object at twice the speed.

[warp]

Steerable axles on trailers weigh more, cost more and need more maintenance. The additional weight of 1500-2000 lbs takes away from payload. In Europe secondary roads are narrow and steerable axles are a must. In North America truck yards are expansive and even secondary roads do not have sharp curves so the cost benefit equation favors fixed axles.

One of the things stressed by good Class A driving instructors to their students is the importance of ensuring that the trailer wheels are moving at the same time as they pivot as the student backs up to avoid stressing those trailer wheels.

On steerable axles, the steer angle on the trailer wheels is remotely controlled and is programmed to mimic the angle of turn of the truck tandems though in the opposite direction. Hence backing such a trailer does not require any more skill than backing up a fixed axle trailer. 

[safristi]

I see many an Ad on Bill boards for "Drivers"...what comes next when an applicant phones the 800 number....rushed training off ya go laddie..................... .......i'm not expecting a novice driver to fix the issue just be able to detect it................but some say even the top mechs at these truck inspections can't always tell so whats UP Doc???...why did we allow these behemoths double trailers on the road.....BUCKS and GREASING the POLS!!!! not the wheels that go round and round............

[Brig]

Turns out the victim was a high-profile executive in the construction industry.

http://www.thestar.com/news/gta/2016/01/29/flying-tire-accident-kills-former-aecon-ceo.html

[safristi]

2017/HR 21/325'S.......................

[tortoise]

No, you can't just double the velocity of the wheel, it's not the same kinetic energy when 2 things each going 100kph hit together as when one object is going 200kph, it's only half the energy as the single object at twice the speed.

However, the amount of kinetic energy possessed by an object is dependent upon the frame of reference.  So if you use the car as a frame of reference then indeed the kinetic energy would be 1/2mV^2 where V was the sum of the two velocities.

[Brig]

No, you can't just double the velocity of the wheel, it's not the same kinetic energy when 2 things each going 100kph hit together as when one object is going 200kph, it's only half the energy as the single object at twice the speed.

However, the amount of kinetic energy possessed by an object is dependent upon the frame of reference.  So if you use the car as a frame of reference then indeed the kinetic energy would be 1/2mV^2 where V was the sum of the two velocities.

[Fobroader]

No, you can't just double the velocity of the wheel, it's not the same kinetic energy when 2 things each going 100kph hit together as when one object is going 200kph, it's only half the energy as the single object at twice the speed.

However, the amount of kinetic energy possessed by an object is dependent upon the frame of reference.  So if you use the car as a frame of reference then indeed the kinetic energy would be 1/2mV^2 where V was the sum of the two velocities.