You have DC powered trains trying to run on an AC powered transformer. To do so, you need a full-wave bridge rectifier hooked between the transformer output and the track.

When you press the whistle button, the transformer supplies a DC voltage to the track to trigger the whistle/horn circuits, and that is why your loco tries to run then.

Trying to run the DC powered loco on AC will burn out the motor.

A power pack with the equivalent DC power of the CW80 is this unit. It will safely run your trains.
http://www.modelrectifier.com/product-p/0001310.htm

Larry