C class waddle??

Just curious to know. I have a film that show's the 268 leaving Crested Butte with I think close to 10-15 cars loaded with coal and as it's pulling away from the depot is really leaning hard to each side as it gets up speed. A later clip shows it around Jacks Cabin fully underway and "cruising" but it still had a slight waddle to it. I have also seen the 318 doing the same thing pulling to passenger coaches--with the operation of the 315 did anyone notice this waddle? I'm sure the 268's extreme rocking from side to side was due to the weight of it's train---it's said a steamer can pull a train it can't really start. Any comments would be appreciated. Thanks.

William
aka drgwk37