After researching this a bit, it seems I will need something more powerful. Through my examination of LGB locos with single motors, it seems that a small 2-4 amp power supply may be OK, but to power locos such as the 0-6-6-0 Mallet and RhB Croc which have 2 big motors you will need some thing much more powerful.
The locos in question require a Marklin AC transformer, which has a special feature... When the loco is to be put in reverse, the transformer sends a 22v jolt that moves an device inside the loco and switches polarity. Most locos these days can deal with the directional stuff without that, but back in the 60's and 70's this is how it was done.