A pulley is a machine in which a rope or cable passes back and forth over one or more grooved wheels. In a pulley system, one end of the rope is attached to the load and the other end is pulled in order to move or lift the load.
A single pulley has only one wheel. The pulley makes the task of lifting a load more convenient since it is easier to pull the rope down than it is to lift a weight up.
Pulleys come in many forms—fixed, movable, cone, swivel, compound, and more. In this post, we’re zooming in on the second type: the Movable pulley.
In a movable pulley, the wheel isn’t fixed to a solid support—the rope is. The load is attached to the pulley itself, and when you pull the rope, the pulley moves upward along with the load. Because the pulley shares the weight, you need much less effort to lift the object compared to pulling it straight up by hand.
Examples of Movable Pulleys in Everyday life
There are many examples of movable or moving pulleys around us. Here are some of the most common examples:
1. Construction Cranes
On big building sites, heavy beams or buckets of cement are lifted using cranes with movable pulleys. The pulley is attached to the load, so when you pull the rope, the pulley itself rises along with the object, making the lift much easier. This setup cuts the amount of force needed almost in half compared to lifting directly.
2. Window Washing Platforms
Have you seen workers cleaning tall building windows while standing on a hanging platform? That platform is lifted with ropes that run through movable pulleys. The pulleys travel upward with the platform, allowing workers to raise themselves without needing a superhuman pull.
3. Elevators
Inside many elevator systems, movable pulleys help carry the elevator car up and down. The pulleys move with the elevator, spreading the weight across several ropes so the motor doesn’t have to work as hard to lift the heavy cabin.
4. Construction Hoists (Material Lifts)
Temporary lifts on construction sites often use movable pulleys attached to a bucket or cage. As workers pull the rope or the motor drives it, the pulley moves upward with the load, reducing the effort needed to hoist bricks, tools, or sandbags.
5. Block and Tackle Systems on Ships
Sailors use block and tackle rigs to lift heavy cargo onto ships. In these systems, at least one pulley is attached directly to the load, so it rises with the cargo. This movable pulley allows sailors to lift barrels or crates that would otherwise be impossible by hand.
6. Theater Stage Curtains
In theaters, large stage curtains are sometimes raised and lowered using movable pulleys attached to the curtain rod. When the crew pulls the rope, the pulley moves upward with the curtain, making it easier to lift the heavy fabric smoothly.
7. Garage Car Lifts
Some home or workshop garage lifts use movable pulleys to raise cars for maintenance. The pulley is attached to the car’s platform, so it goes up as you operate the system, letting even a small motor lift a heavy vehicle.
8. Rescue Stretchers in Mountain Climbing
When rescuers need to lift an injured person up a steep cliff, they often use a rope and movable pulley system. The pulley travels with the stretcher, reducing the force rescuers need to apply while keeping the lift smooth and controlled.
9. Portable Well Buckets
In some deep wells, a movable pulley is attached to the bucket itself. As you pull the rope, the pulley moves upward along with the bucket, making it easier to draw heavy water compared to pulling it straight up.
10. Gym Weight Machines
Certain weight machines in gyms use movable pulleys connected to the weight stack. When you pull on the handle, the pulley moves with the weights, allowing you to lift heavy plates while applying a manageable force.
11. Zip Line
On a zip line, the pulley that rides along the cable moves with you as you glide from one end to the other. The wheel isn’t fixed in place—it rolls along the rope or wire while carrying your weight. This moving pulley reduces friction and lets you travel smoothly and quickly down the line.
12. Patella (Kneecap)
Your own body has a movable pulley built right in: the kneecap. The patella acts like a small pulley that slides as you bend and straighten your knee, guiding the tendon over the joint. This movement helps your leg muscles lift and straighten the leg with less effort, just like a pulley system at work inside you.