Iron Dragon chassis question

I've long wondered about a particular part of the Iron Dragon train. It's the small, crooked piece on the back of each wheelset (running wheels) that appears to slide front to back in a slotted bracket on top and attaches (presumably) to the chassis of the car. Does this help the wheels track better? Some sort of passive steering? I was at PKI on Aug. 4, and noticed that Top Gun does not feature this part. Maybe in the time span (1987-1993) between these coasters this part was found to be uneeded?

I believe that is a safety arm.

The arm attaches to the wheel carrier, extends behind it, and over the track. If the train should lose a wheel, or if it should lose the road wheel assembly, that arm should catch the car.

The Top Gun wheel carrier is designed differently. The axle cross-arm has a set of safety pins on it above the attachment pin and between the road wheels, so if the attachment pin (or a road wheel) goes, the safety pin will land on the track. I'll try to find some appropriate illustrations, but at first glance I don't seem to have any handy...

--Dave Althoff, Jr.

Thank God for Dave's infinite ride wisdom ;).