what do i need?

[george71]

new to this..bought a cheap bachmann set & later got passenger cars (4) and the power unit will not pull them..what do i need to do?

[Pacific Northern]

You need to define your problem in such a way to explain what is wrong.

First of all which set did you buy and which scale is it?

You mentioned you later obtained 4 passenger cars, please tell us the manufacturer and model.

Engine will not pull cars? Does that mean the engine will run on its own? How many passenger cars can the engine pull if any?

What is the basis of your layout and what size is it?

[SteamGene]

What is the locomotive? (Type, not road or part number - Bachmann 2-8-0, F7, GP40, etc) Does it have horn hook couplers or knuckle?  (Horn hook look realy strange while knuckle look very much like real train couplers.) 
Gene

[Yampa Bob]

If it will run at all, put it on the track by itself and break it in at full throttle for about 30 minutes. The mechanism might be very tight, could even use a bit of lubrication.

The cars must roll freely on their own, or the loco might not pull them.