modern 4-4-0 locomotive pulling power

[UP5521]

I have a bachmann Modern 4-4-0 American in HO-scale that is based on the prototype of Maryland and Pennsylvania #4 and my locomotive can't haul no more than 2 cars and I was wondering if there is anyway to increase this locomotive's pulling power and thanks!

 

[whitepass]

Add wight over the drivers and/or put in a bigger motor.

 

[American_Connections]

Hidden power

You could make a power unit as a passenger car to add to the power of the 4-4-0.