Six axel passenger cars

It was all about the total weight of the car, when full to capacity.

     The six wheel trucks do ride better than four wheel trucks.  On a four wheel truck, when a wheel drops, like at a low joint, the trailing wheel is still at the normal hieght.  In between the two axles is the bolster with the carbody sitting on it.  The bolster drops only half the distance, thus the carbody drops only half of the distance. 

     On a six wheel truck there are two bolsters connected by a span bolster.  The carbody sits in the middle of the span bolster.  When a wheel drops on the six wheel truck, the boster drops half the distance, as it is half way between two of the axles, and the span bolster drops half the distance the boster drops, as it is half way between the two bolsters.  Thus the carbody drops only 1/4 the distance that the wheel droped.  Half as much as the carbody on a four wheel truck dropped.

If you saw a dome car with six wheel trucks it was probably one of the "Superdomes" the full length dome cars.  These were probably the heaviest passenger cars ever built, approaching 150 tons as I recall.  The extra weight was the result of the increased air conditioner systems to overcome the hear coming through the dome, plus all the extra framing to support and maintain the huge structure of the cars.

Paul Fischer

Most if not all of the older "heavyweights" have six-wheel trucks, as has been mentioned because of the weight of the car. The Washington DC Chapter's Dover Harbor, shown in the photo, weighs 90 tons. As if the steel was not heavy enough, there is a poured concrete floor as well.

B&OBill

Poured concrete?

Probably for Ballasting I bet.

It is my experience from the Gettysburg Railroad, the cars with 6 wheel trucks were valued for the smoother ride over the 4 wheeled trucks. The track in those days... well... they were more or less in gauge.

Strasburg is much better. We enjoyed the 4 wheeled cars for the Clickety clack. I cannot recall if the old Yellow open car "Hello Dolly" had 6 wheel or not. (Whatever happened to that one, anyone know?)

There have been on occasion am track's Texas Eagle come through with one to three privates in tow. Always when I dont have my camera.

Lee, here's what I found on Trainweb:

"The cars were called "heavyweights" for a very good reason. Besides the steel used in construction, the cars often had a six inch slab of concrete cast into their floors. This added a lot of sprung mass which made the car bodies tend to resist the tendency to bump and bounce over track irregularities. This resulted in significantly improved riding qualities, especially at the high speeds often used in the late steam era. Only significant improvements in suspensions allows the newer and lighter streamlined cars to ride better."

B&OBill