How to make a pulley
There are 3 types of pulleys.
1. Fixed pulley- a fixed pulley stays in place as the rope is pulled through it.
2. Movable pulley- a movable pulley moves with the rope as it is being pulled.
3. Compound pulley- a compound pulley system uses a combination of both fixed and movable.
How to make a simple compound pulley
What you will need:
- 2 wheels from a K’nex set
- 7 paper clips
- 1 – 3 pound hand weight. If you don’t have a hand weight, you can use an unopened can of food.
- Bend open 2 paper clips into an S shape like this:
- Tape the long S shaped paper clip to the kitchen counter or a table leaving just a bit of the end extending over the edge, and hook another paper clip to each end.
- Pop off the black rubber tread on the 2 K’nex wheels.
- To make your pulley, straighten out a paper clip and slide a k’nex wheel to the center of the paper clip. Bend the paper clip until it touches at the top and squeeze it tight to the wheel. Twist the ends together and then bend the ends to form a hook.
- Repeat on the second k’nex wheel.
- Tie a string securely around your weight and tape it in place to keep it from slipping, then hook a paper clip to the string.
- Hook one of your pulleys to the paper clip attached to your weight, this is your movable pulley.
- Hook the other pulley to one of the paper clips attached to the counter or table, this is your fixed pulley.
- Measure the height of your counter or table and cut a piece of string 2 ½ x the length.
- Tie one end of the string in a loop and hook it to the remaining paper clip secured to the counter or table.
- Run your string through the movable pulley on your weight, then through the fixed pulley. Adjust the string so that it is in the track of the wheel.
Your compound pulley system is complete, it’s time to give it a try! First test how heavy your weight is without using the pulley. Now try your pulley system.
How to make a simple movable pulley
To really test your strength with the help of movable pulleys try this fun pulley vs. people tug of war.
You will need:
- 40-50 feet of rope (close line rope works well)
- Two broomsticks
- And two of your strongest friends
- Have each friend hold broomsticks with both hands (we will call them broomstick A and B). With arms extended, stand so the broomsticks are about five feet apart.
- Tie one end of the rope to broomsticks A, and then loop it once around broomstick B.
- Stand a few feet behind the friend with the broomstick.
Can you pull your big strong friends together? Probably not.
Now loop the rope around broomstick A and back around broomstick B. Stand in the same spot and try to pull them together. Any easier?
How about if you loop the rope around broomstick A and B again? I bet you and the pulleys are winning the tug of war now! Each time you loop around the broomsticks it will give you even more of an advantage.