There are different ways you can make pulley systems out of cardboard. I have created a new system that is clever and works really well.

A typical way to do a pulley system is to use two pulleys and a rubber band between them. Like this:

You can see the two pulleys with a rubber band as the belt that goes around both of them.

Here is the new way to do it.

The pulley on the right is just a normal pulley with a little handle on it so you can turn it.

The string is just average string. But it is tied with an Arbor knot so you can tighten it and it will not slip. Clever little knot.

The real secret to this improved pulley set up is the idler pulley and tensioner that you see on the left.

This idler pulley and tensioner is a great way to keep the pulley string taut regardless of any inconsistencies in the spinning.

It's easy to understand.

The pin at "A" is the pivot pin. This pin goes all the way through and into the sheet of cardboard that is our base.

The pin at "B" is only for the pulley to rotate on. It doesn't go into the base. Here is a sideways look at it.

So, "A" is the pivot point.

The Rubber band at "C" keeps tension on the tensioner. THe whole thing pivots on the pin at "A".

You can adjust and knot the rubber band so it keeps just a firm amount of pressure on the tensioner arm. This rubber band tension will make up for any irregularities in your pulleys. You get a nice and smooth pulley action.

Let's take one last look at how I am using it in this train derailment game.

The Captain America shield goes back and forth when you turn the hand crank. This is achieved by Gluing the bottom of the cardboard that the shield is on to the string. This is shown by a series of black dots.

The other part, where the other string is, (marked with X's) has no glue. The cardboard just slides over that string.

You can see this pulley set up in action. I have something called the train derailment game. Here is a video: