Nervous Nancy Wrote:
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> I see from the NW Railway Museum blog that they
> put this old coach on trucks.
>
> Question: Without the truss rods installed,
> aren't the structural members in the side sills
> under a lot of stress? I am biting my nails
> looking at this situation. The truss rods are
> tension members that keep the body from sagging.
> So what's to keep the car from breaking in two?
>
> Yours Sincerely,
> Nervous Nancy
> Lester, Wash.
>

The car siding is acting like a diaphragm, spreading the load throughout the car and lessening the strain on the side sills. Left unsupported, the car would eventually start to sag and possibly snap in half, but that would happen over time. An outside force, like a sudden shock, might also cause too much stress for the supporting members, so care must be taken in situations like this.