Why are freight train cars wheels/axles always detached in accidents?

Question

Why is it every time I see freight trains in accidents that the freight car wheels/axle assembly is detached from the axle truck? Do the cars just sit on the axles and the axles are not secured to the wheel truck?

Answer 1

the cars are sitting on springs. the wheele are free to move. in a wreck what little holds them on goes first. they are hooked on, just not well

Answer 2

Actually the AAR (Association of American Railroads) rules require the car no stenciled on either both sideframes or the bolster of each truck (or bogie).   Every wheel is marked by the shop the mounted it, and every bearing is marked by the shop that mounted it and the date.

Since shops must keep records, it is very easy to trace the history of a wheelset.

In addition, the castings are marked by the manufacturer, dated, and pattern numbers.  Thus if a manufacterer produces faulty products, they can be recalled quickly, and the manufacturer held accountable.  In theory anyway.  The last major recall was of castings made by a manufacturer that was out of business by the time failures were occuring.

Answer 3

yes they just sit on the bear pad which is inside a box clled the journal and thyis is filled with a heavy oil which keeps everything from getting to hot from huge weight of the load carried on the frieght car

Answer 4

Freight cars do not have locked center pin assemblies between the frame center plate and the truck bolster. Likewise, the wheelsets are not locked to the truck frame.

The frame uses its weight to stay centered on the truck bolster. The frame has a center plate that sits into a cast bowl in the bolster. There is also a small guide pin that protrudes up into the frame from the bolster.

The bolster transmits and equalizes the weight to the sideframes of the truck assembly via a nest of high capacity springs and hydraulic stabilizers.

The truck assembly  sits on top of the ends of the wheelset axles. This section of the axle is called a journal and is where the bearing assembly is placed.

Today, anything that is interchanged between railroads is required to have roller bearings.

These sealed roller bearings are open and have adapters that sit on the bearing and the sideframes sit on the adapters.

In addition, there are "side bearings" on top of the truck sideframes to keep the car stable and avoid rocking heavily side to side.

   As you see, nothing is really locked together. It is all held in place by weight.



When a railcar is derailed and rolls over, or other such unhappy circumstance, the wheels, trucks and axles are free to come apart. And trust me, they do. I know from experience.

Being held by weight is nothing new and has been the practice for ages for freight cars.

The advantage is when they are shopped for repair or replacement of wheels and trucks, it can be done quickly and efficiently to keep the large commodity on the move to the customer.

On the other hand, passenger cars, or least older ones, had locking center pins between the frame and truck bolsters.

There are different weight classes of trucks, 50ton, 70ton and 100ton are the most common. The bearing sizes differ between them

There is an animated freight car truck disassembly on the top of this web page that will show you a little of what I explained.

http://www.amstedrail.com/freightcar/ind...

I hope that helps.

Answer 5

The gentleman above is quite correct.  

Some railroads have the car number painted on the trucks that the car sits on.  This is a handy investigative tool when equipment does scatter all over the place, to help in determining what belongs to which and perhaps completing the picture when trying to determine the cause of the derailment.

Answer 6

The wheel and axle assembly sit on the track.  The truck assembly sits on the wheel/axle assembly.  The truck has a bolster pin, which is a vertical pin sticking up from the centre, that fits into a hole in the carbody.

There is no actual device that secures these pieces together - it's only their immense weight that keeps them together.  But, except for big wrecks and repairs, they stay together rather well.