The pulley, widely known as one of the “simple machines”, was among the first machines ever used by humans. The pulley consists of a wheel attached to the axle, and around the wheel a rope is attached to lift and move heavy objects. Pulleys allow you to change how things work, such as pulling a rope to lift a box. There are several types of pulleys: fixed, movable, or double.
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Method 1 of 3: Keeping the Pulleys Simple
Step 1. Prepare the necessary equipment
A pulley is a simple mechanism, and can be a great way to teach children certain concepts, such as strength, gravity, and efficiency. If you want to make a simple pulley, prepare the equipment mentioned below. You can replace items that don't exist with other items. This will be discussed later.
- Wire coat hanger
- Yarn, rope, or cable (at least 3 m)
- A wooden bobbin, like the one used to wind yarn (with a hole in the middle)
- Expenses for testing (e.g. a half-filled milk bottle, a book, a piece of pipe, etc.)
Step 2. Cut the wire at the bottom of the hanger, right in the middle
Stretch it so that you can insert a wooden bobbin, which will act as a pulley, in the center of the wire. The hook at the top of the hanger can be held or hung from the ceiling to allow the pulley to stand on its own. If you don't have hangers, you can use:
- Skewers, nails, or long sticks that you can hold at each end.
- The rope is tucked through the bobbin, then tied at the top.
Step 3. Insert the exposed end of the wire through the bobbin
Carefully stretch the cut wire and thread the bobbin on a coat hanger. If you don't bend the wire too much, it will be easier to insert the bobbin while keeping the wire in position. If you can't find a wooden bobbin, try these items:
- Ready-made pulley wheels can be purchased at most hardware stores for around $50.
- Pulley wheels can be found in toy sets, such as Lego building blocks.
- A spool of ribbon like the one used to wrap gifts.
- A roll of toilet paper or a roll of paper napkins (in an emergency).
Step 4. Close the hanger wire to secure the bobbin
You may have to bend the wire around the bobbin, just bend it slightly to hold the bobbin in place if the bobbin is too heavy for the wire. You can do this by pushing the two ends of the hanger closer together until they are only half their initial length. Then bend both ends up so the bobbin won't go through it.
Step 5. Loop the rope over the pulley
This step is very simple. You just need to drape the rope over the pulley. When you pull on one end of the rope, the other end will shorten as it moves up.
If you want to do a lot of experimenting with pulleys, you can attach a small metal hook to one end of the rope, allowing you to hang and test different loads with ease
Step 6. Hang the pulley system and make sure the pulley wheel can rotate smoothly
Hang a coat hanger hook on top so that the bobbin and rope hang down and rotate easily. You can also ask a friend to hold the hanger hook. If you're using a stick or towel around the bobbin, you can place the two chairs close to each other and balance the dowels over the two backs.
Step 7. Tie a weight at one end of the rope
The pulley facilitates work by distributing the load and force along the “different” sides of the rope created by the pulley. Pulleys also allow you to lift things more easily, just pull the rope down and use gravity to help. Feel the weight of the object you are experimenting with (half-filled milk bottle, thick book, etc.) before attempting to lift it with a pulley so you can make comparisons.
If your school has a force meter, use it to test and record the weight before using the pulley
Step 8. Pull one end of the rope to lift the weight easily
Even tight pulleys (wheels don't turn smoothly, ropes get stuck, etc.) will allow you to lift books more easily. What is the reason? This is because when you pull the rope down, you move with gravity, making the movement more efficient. Even the most complicated set of pulleys, known as “block and tackle” (a system of two or more pulleys with a rope or threaded cable between them) allows a person to lift a car alone, although you will need the help of multiple pulleys used together. Weigh the load with the help of a force meter to see how the pulley makes it easier for you to lift things.
Step 9. Ask yourself a few questions while setting the pulley to test your experiment
What happens if the rope is longer? What if you use a larger or smaller pulley? Pulleys teach a lot about forces, gravity, and machines. What can you learn? Focus on finding ways to improve the pulley's effectiveness in order to test how each component of the pulley works.
- What would happen if you added two or more pulleys to the system, and slipped a rope through them? Would it be easier for you to lift weights or more difficult? The answer is easier.
- Is the weight being lifted by the same amount as you are pulling the rope? The answer is yes; The length of the string remains the same, so the lengths on both sides of the pulley will always increase by the same number.
Method 2 of 3: Making a Fixed Pulley
Step 1. Choose a mounting location that is strong enough to support the weight on the ceiling
You need to screw the pulleys into the beams or roof rafters, not the gypsum board. The pulley is designed to make it easier for you to handle heavy objects, but the entire weight must be supported by screws attached to the ceiling. If you don't know how to find the right location for the pulley installation, maybe you can hire a professional to install the pulley.
Step 2. Purchase a simple fixed pulley system
Of course you can make your own pulley wheels, buying axles and mounting frames to suit the size of the wheels and axles. However, ready-made mounting wheels and frames cost less than IDR 150,000, not worth the effort to make your own. Ready-to-use pulley systems have all components measured and tested to ensure they work properly.
Step 3. Install the axle through the center of the wheel
If the pulley wheel is not equipped with an axle that can be easily installed at the mounting point, you will have to insert the axle manually. You can simply thread it through the wheel, applying a small amount of all-purpose oil (eg WD40) all over to loosen it up.
Step 4. Attach the axle to the ceiling with the help of the included screws
Fasten the axle to the wall or ceiling using the appropriate tools. Usually, you will need to use a hammer and nails to attach the axle to the installation site, or use a drill and long screws for systems that handle more weight. Again, if you are not comfortable doing it yourself, contact a professional or a friend with experience in this matter.
Often a fixed “block” or pulley will have a hook. In this case, you can simply attach the screw ring to the ceiling and attach the pulley system hook to the ring
Step 5. Make sure the wheel can rotate freely
The wheel must be able to turn without experiencing obstacles. Tighten all screws carefully so that no parts wobble, and apply a small amount of lubricant to moving parts in case of jams.
Step 6. Insert the rope over the pulley
You must thread the rope along the “rails” or between the grooves at the top of the wheel. Make sure the strap is attached to the top half.
Step 7. Hang a weight from one end of the rope or attach a hook to make a pulley that can be used over and over again
Take the end of the rope that will not be pulled and tie a weight. You can tie objects directly with string or make simple hooks.
Step 8. Test the pulley
Pull the other end of the string and let the pulley change the direction of the force. If the pulley is working properly, you should be able to lift the object up to the axle.
Method 3 of 3: Making Double Pulleys (Moving)
Step 1. Design the pulley system first
A pulley system is a great way to lift heavy objects with as little force as possible, but it must be properly installed to operate. Find the right diagram online because you can find every type of pulley imaginable there. You must know the differences between each pulley system to understand the diagram:
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Fixed pulley:
The wheel of the mechanism turned, but the rest didn't move. The rope just goes through the top of the wheel. You pull one end down and the other end up. There is an axle in the center of the wheel.
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Moving Pulley:
The pulley has a hook in the middle, no axle. So, this kind of pulley is almost always used with other pulleys. As you pull on the rope, the area around the pulley shortens, allowing you to lift and reduce the weight and length of the rope. The load that must be lifted is usually attached to the hook.
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Double Pulley:
Let's take an example and imagine a hanging PowerPoint screen. You pull the rope on one side, but both sides go up at the same time because the same rope is attached to both sides. The rope goes through the left side, then to the right, then back to the double pulley on the left, where you pulled the rope.
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Block and tackle system:
This type of mechanism refers to a series of pulleys and ropes that you use, and in this system the rope goes through the same pulley 2-4 times. In general, such mechanisms are provided with specific assembly instructions.
Step 2. Make sure you have a secure platform to place the pulleys on
The entire mechanism must be mounted on a support post or truss. If you don't have this kind of facility to securely attach the pulleys, you can build a platform. Mount the two pulley systems on a 2x4 board. This construction is known as a “vertical block” system because it has a fixed position to form a fixed pulley. Then, securely attach the boards to the ceiling or roof. Install it approximately 30 cm above the standard 2x4 board.
The 2x4 board should be high enough, slightly above the position where you want to lift the object with the double pulley
Step 3. Mount the pulley on the board or ceiling according to the instructions in the diagram
For this example, you can use the most common dual M-shaped system. To do this, install the pulleys in a line, with the two fixed pulleys on the outside and the moving pulley in the middle. However, the movable pulley is not fixed to the ceiling, but is held in place by a rope. For now, align the two fixed pulleys and screw them in.
- Make sure you use the right level, straightedge, and measurements to make sure the two pulleys are level.
- There should be an equal distance between each fixed pulley and the center pulley.
Step 4. Wrap the rope through the bottom of the moving pulley
Start winding the rope around the third pulley, which isn't attached to the board. This system is known as a moving block. The rope runs through the bottom of the wheel, and most movable pulleys have small metal tabs that prevent the rope from slipping.
Step 5. Insert the rope into the other two pulleys
Wrap each side of the rope through the other two pulleys. Now, the moving pulley will hang from the top of the two fixed pulleys. The rope will be at the top of each fixed pulley and at the bottom of the moving pulley.
The rope should form an "M". The rope will descend from each end of the pulley that is on the edge and through the bottom of the moving pulley that is in the middle
Step 6. Hang the object you want to lift on the movable pulley
Hang the item you want to lift from the bottom of the movable pulley, attaching it to the hook. You may have to use a bench or hold onto the rope to keep it from jerking down if it's not long enough.
