What "ladder bars" were designed to do in theory is to lift the front of the car, acting like a long lever, which in turn plants/pushes the tire down on the pavement. A traction bar at maximum efficiency would make the car do wheel stands.
Called Ladder bars because the look like a ladder. 2 semi parallel bars with cross bracing.
Here is a link explaining the basics of each type of traction device.: https://www.moroso.com/pub/media/pdf/UnderstandingSuspensionBasics.pdf
