Poor traction for a 6-8-6 of this weight. My MTH PRR 4-4-0 scale Atlantic easily out pulls it.
The Lionel 6-18018 is a 2-8-2 Southern Mikado locomotive. I would consider replacing the traction tires. I believe the 242-206 woudl work fine and is available from most parts suppliers, including form sponsors @S AND W and @Harry Henning respectively:
Getting a little more involved would be to take a gander at the service manual for the locomotive and tender:
wrong number, it is the scale PRR turbine,not made with tires.
There are a few editions of the turbines - care to confirm its number?
6-38028 has traction tires: https://www.lionelsupport.com/...ec-bb5c-338cc2521727
6-11416 has traction tires: https://www.lionelsupport.com/...5d-9ad9-9fb74aa22855
6-18010 was a scale S2 without traction tires. Catalog stated "Spoked drivers with metal rims".
It is the 18010 scale turbine
What are you trying to pull with it? What kind of track are you using? How steep are your grades, how sharp are your curves? All of these things are important. The scale Turbine is a huge locomotive! If your trackwork isn't perfect, all of the wheels may not even be touching the railhead.
Also, did you check that the wheels on the tender turn freely and aren't creating extra drag? The Turbine tender probably weighs as much as your 4-4-0!
There are folks who specialize in cutting grooves into the wheels, and adding tires. They perform this as a regular service. Personally, I despise rubber tires and prefer a little wheel spin when starting a heavy train. Let's try to cover the basic issues above before we get into modifying the loco.
Make sure the track and drivers are clean and start out slow. Kind of like a real train.
All of the track questions are important ones. My first thought was round rail heads and flat wheels, bent down track between wide spaced tinplate ties, and tight curve diameters. You might try a .001 or .002 feeler gauge or sheet of paper under each wheel to explore the track contact on each wheel set.
Also, drawbar offset shapes and angle of the L bend can effect balance and cause lift up at the rear under heavy loads (or pulls down, squating the rear and loading more on the rear drivers, which is better but not ideal traction either)