I was under the impression that someone got in on the ground and then made the arm go up while carrying things and at the end of the day, the person made the arm go down and went home.
But cranes are always up at night. So what do they do? How do they work?
In: Technology
You are going to have to be more clear. There are many kinds of cranes, that do many things. Are you talking about a truck mounted crane, a construction crane that is 40 stories tall, a cargo crane for moving cargo on and off of ships? Give us a little bit more to work with here.
they have a ladder for the person to get to the arm, and at the end of the arm there is a pully sytem that lets down a very long chain or cable, that chain/cable is attached to what needs lifting, the the cable is spooled up, bringing the materials with it, and at the end of the day the person in the crane climbs down the ladder to the ground
Often cranes are up at night to hold valuable equipment and materials up off the ground to make these materials and equipment harder to steal.
If you’re talking about the big tall ones that look like the letter T, they usually get assembled (or rather, sort of assemble themselves) at the beginning of the project by adding vertical pieces and raising the top part (the “arm”) as more are added, then there is a [little elevator](https://youtu.be/P1wmkxE4Gek) that the operator takes up and down when they are done for the day. The ones on trucks or that don’t have the big tall vertical bit usually have the operator area closer to the ground.
As another user mentioned, they might also hold stuff on it at night to make it harder to steal. Same reason you’ll often see excavators left with the scoopy bit resting on other attachments or equipment. Basically the Thor’s hammer approach to security heh.
Cranes work because of pulleys. If you want to lift something off the ground, you are actually lifting the weight of the object and the weight of yourself also. It’s the most ineffecient way to lift something.
It’s a lot easier to lift something if you use a pulley. Basically tie a rope to the load and feed it through a “block”, so that you pull down on the rope, and the object goes up.
It’s easier to pull down on the rope because you have gravity working with you, not against you.
The interesting thing is that if you add more ropes and more blocks, you increase the mechanical advantage. So if I tie multiple ropes to the object and feed them through many blocks in the same setup as before, you can pull the rope down with an input force of let’s say 1 and the object would be lifted by let’s say 4 ropes and you would have 4 times the lifting power.
cranes are like giant robot arms that lift heavy stuff without a human on the arm. they use motors and controls to move up and down. at night they just chill up there don’t worry about them they can take care of themselves
I assume you’re talking about crawler cranes that you see in road construction or similar ventures.
https://images.app.goo.gl/RzrgsvuinXD1d8AH6
So.. this is a friction drive crane.
Almost all of its functions are driven by a clutch and brake system. The brake system has an air driven mechanical locking system. Kind of like the hand brake on a car. But it locks when the air pressure is released.
So the operator gets in. Starts the engine, Closes the air tank release valves, builds up pressure in the tanks and then is able to release all the mechanical brake locks.
He does his duties with the machine. Operating it in a safe and controlled manner and being mindful of all the redundancy features and settings.
Then at the end of the day. He positions his crane in a safe direction. Holding any valuable items up out of reach of thieves. Like generator trailers. Or mixing plants. Or light towers. Then he sets all his brake mechanisms and redundancies, Shuts the engine down and purges his air tanks.
ELI5.
Crane is very large and very strong. It can easily hold itself up when you tell it to stop and wait. And it won’t move again until you tell it to go.
so cranes are like giant robotic arms that lift stuff. they have a cab at the top where a person controls it. they dont just go up and down like you thought. they use pulleys and counterweights to be stable and lift heavy things. even at night they stay up to keep construction sites safe. nobody wants to step on a crane in the dark right?
Latest Answers