The current draw in the Factory service Manual is for new engines on level track with a light load. Put that dual motor Alco on a 4% grade pulling 5 lighted passenger cars and dummy A and B units the complete consist will draw at least 5A. The 4B is 100W input, not output. The output is 75 to 80 watts, basically a 5A output transformer when continuously loaded. It will run the consist I describe plus 2 pairs of track switches and a Talking Station and billboard whistle. After 15 minutes running the train and accessories it will be hot to the touch.
I have no experience with DC supplies for track power other than HO and N. My HO supply was 80VA, it would not run my AF trains. My recommendation is at least 5A for each Gilbert train you want to run plus a separate supply for all the lighted accessories. I used a dedicated 4B just to power all the turnouts (8 pairs) with their lighted controllers.
Be careful about the ratings, almost all are input or primary side VA or watts. Multiply the input rating by 80% to approximate the output rating. If operating Gilbert trains with universal motors use .9 for the power factor to convert VA to watts. For example a 150VA AV power supply input rating is 150x.8x.9=108W output. At 15V it will supply 7.2A. If the output is filtered DC leave out the Power Factor. All this a good reason to switch to high efficiency can motors.
Sorry about the italics, not sure what I did.
