- 4 months ago
Category
🐳
AnimalsTranscript
00:01Elevators revolutionized the way we build and live in our cities.
00:05In this video, we'll be exploring the different parts of an elevator, how it works,
00:10and then the safety mechanisms which protect us as we ride these amazing machines.
00:23In the 1800s, architects and engineers were pushing the boundaries of how high we could build.
00:28As these buildings increased in height, there was somewhat of a limit.
00:32It was hard to utilize the upper floors because you had to walk up a lot of stairs,
00:37and no one really wanted to do that every day.
00:40The reason we started to build higher is because of elevators.
00:43In many parts of the world, it is referred to as a lift, but in this video, I'll use the word elevator.
00:50The elevator is not a recent invention.
00:53The idea of using a machine to lift things in the air, this is not a new idea.
00:57It can be traced back to ancient civilizations over 2,000 years ago.
01:02Various lifting devices such as hoists or cranes, these have been used in various places like factories and construction sites.
01:08But lifting people, that usually wasn't done.
01:11If that rope snaps, there is nothing stopping you from falling to the ground.
01:16In the early 1850s, Elisha Otis invented a safety mechanism that changed everything.
01:22Let's take a look.
01:25This is a simple lift that can be raised or lowered by the rope.
01:30The safety mechanism is made up of a leaf spring, two pivot arms, and the teeth on both sides.
01:38When the lift is being pulled upward, the pivot arms are rotated, allowing the elevator to rise.
01:45But if the rope suddenly loses tension for any reason, the leaf spring immediately pushes the pivot arms down, which then comes in contact with the metal teeth.
01:54This stops the elevator from falling to the ground.
01:57Mr. Otis was so sure of his invention that he demonstrated it to a crowd of people at the World's Fair.
02:03He lifted himself up on the elevator, and then had someone cut the supporting rope above.
02:09He only fell a few centimeters.
02:11This demonstration convinced the public that elevators could be safe enough for people to ride.
02:16Elevators today have multiple safety mechanisms in place, but it all started with Elisha Otis.
02:22Over the coming decades, elevator shafts became the core of most buildings.
02:27This allowed for skyscrapers to reach new heights, and for the buildings to be fully utilized.
02:34And of course, we have to mention the revolving stairs, or more commonly known today, the escalator.
02:40Helpful for moving large amounts of people, but only up a few floors.
02:44Once those buildings get really tall, the best solution? The elevator.
02:49Ah, that music. But for this video, we'll pick up the pace just a little bit.
03:04Let's go over some basic parts of the elevator.
03:06Now, there's a lot of different elevator companies, and different ways to make elevators.
03:10Some of the mechanisms and names will be slightly different depending on the elevator.
03:14So, keep that in mind.
03:15This is called the shaft, or the hoist way.
03:20The elevator pit at the very bottom.
03:23Then we have the cab, which moves up or down inside the shaft.
03:27And these are the guide rails.
03:30The cab usually has guide rollers to move it along the rails.
03:36There are two main types of elevators.
03:40Hydraulic elevators and traction elevators.
03:43In real simple terms, traction elevators lift the cab from above using cables,
03:48and the hydraulic elevators push the cab up from underneath.
03:52For most of this video, we're going to look at traction elevators.
03:55These are the ones you'll find in really tall skyscrapers.
03:58But first, let's at least get the basics of the hydraulic elevator.
04:02This uses a cylinder and a piston.
04:06These usually extend several floors beneath the ground, so there's enough length to push the elevator up.
04:13Close by, you'll find a machine room with a pump unit filled with oil.
04:18When the elevator needs to go up, the oil is pumped through the pipes and into the cylinder.
04:24The pressure pushes the piston up, which raises the elevator into the air.
04:29You'll find hydraulic elevators in smaller buildings, usually not more than six stories tall.
04:34This is due to the length of the cylinder and the pressure involved to push the piston up.
04:40Okay, traction elevators. Are you ready?
04:43Traction elevators are most common in taller buildings.
04:46In some places in the world, these elevators can service more than 100 floors.
04:51Let's not get too carried away though. I'm going to demonstrate this with just four floors.
04:56We'll keep things simple.
04:58At the very top is the machine room.
05:01This is where you'll find the electric motor.
05:05The motor pulls the cables by turning the shiv, which is basically a special kind of pulley.
05:10On one side, the cables go down and attach to the cab.
05:14And on the other side, it attaches to the counterweight.
05:19The counterweight moves opposite to the elevator cab.
05:24So why do we have this counterweight?
05:27Without the counterweight, the motor would have an enormous amount of tension on only one side.
05:32It would have to work a lot harder to lift or lower the cab.
05:38The counterweight makes it so that there is less strain on the motor.
05:41All it has to do is tip the balance so the elevator moves up or down.
05:46The counterweight will weigh as much as the cab when it's about halfway filled up.
05:50Ideally, the system will work best if it's perfectly balanced.
05:54But this won't always be the case.
05:56The weight of the elevator cab will frequently change.
05:59This is the controller box.
06:02It's like the brains of the elevator, safely moving it up and down.
06:07Not all traction elevators are going to have a dedicated machine room.
06:11They're able to fit the motor and other components at the very top of the elevator shaft.
06:15They refer to this as a machine room-less elevator, or MRL.
06:19We won't go into detail about these, but I at least want to mention them so you know that they exist.
06:24Elevators have many safety features built in to protect the passengers riding in the cab.
06:30First, you have the machine brake.
06:34This is used to stop the spinning of the motor and hold the cab steady.
06:39There are usually at least four cables holding up the cab, sometimes as many as eight cables.
06:44Each of these cables is strong enough to hold the weight of a fully loaded elevator.
06:48The likelihood of all of these cables snapping is very small.
06:51But if it did happen, you would still be safe.
06:54Let me show you.
06:55Do you remember Mr. Otis' safety mechanism at the beginning of this video?
06:59The modern version of this is a little different, but the main idea is still the same.
07:03At the bottom of the elevator cab is the emergency brake.
07:09There are two clamps, and these are located on both sides of the guide rail.
07:14Normally they don't touch, so the elevator is allowed to move up and down.
07:20But if the lever is pulled, then they move in and grip the guide rail,
07:24which stops the elevator from falling.
07:27The lever is connected to a cable, and this is a separate cable from the ones that lift the cab.
07:32This cable attaches to another wheel at the top.
07:35Let's take a look.
07:36Back up here in the machine room, this device is called the overspeed governor.
07:40Normally this spins along with the elevator cab as it moves up and down.
07:45Inside is a mechanism with two flyweights.
07:50Let's say, for whatever reason, that the cab starts to move downward too quickly.
07:56The overspeed governor will spin faster.
07:59If it spins too fast, these flyweights will move outward and catch the gear teeth on the side.
08:04This will stop the spinning, which stops the cable, and the weight of the cab now causes the lever to go up.
08:14And there's clamps on both sides of the elevator which firmly hold it in place.
08:19Now if you do happen to get stuck in an elevator, don't try and force the door and climb out.
08:24Press the emergency call button to get connected with someone who can send help.
08:29Let's talk about that door mechanism.
08:31There are essentially two doors on an elevator.
08:35On each floor, you'll find a door.
08:38These are usually called the hoistway doors.
08:43And then on the elevator cab itself, you'll find the cab door.
08:49So when these are together, we have the cab door and the hoistway door.
08:55We don't want either door to open unless the cab has come to a complete stop at the correct floor.
09:00These doors also have sensors so they won't close if something is in the way.
09:05And the elevator won't start moving until the doors are completely closed.
09:11Let's look at just the cab for a minute.
09:13The door operator is located at the top.
09:16This turns some gears, which pulls on the lever, which slides the door open.
09:22Notice how each of the hoistway doors does not have a way to open by themselves.
09:31The doors can only be opened by the door operator on top of the cab.
09:35When this opens, it will pull the hoistway door with it.
09:42Each of the hoistway doors has an interlock.
09:45This ensures that it won't open until the cab is right behind it.
09:48Let's look at the mechanism.
09:51Each hoistway door has a beak.
09:53When this is down, the door won't open.
09:57Push up on this bar and the beak goes up.
10:00This allows the door to open.
10:03Down below, you'll find two black pickup rollers.
10:08Push the one on the left and it rotates.
10:11Which pushes up on the bar, which unlocks the door.
10:18So, how does this get unlocked then?
10:21Well, I'm glad you asked.
10:23On the cab door, there's a piece called the clutch.
10:26As the cab moves up and down, the clutch moves right around the rollers.
10:31When the cab stops, the cab door will open.
10:37The clutch will push on the pickup roller, which will unlock the mechanism.
10:42Both doors can now slide open together.
10:46In a rescue situation, or maybe even for maintenance,
10:49the workers can use a special key to unlock the door even if the cab isn't right behind it.
10:54Now, a key like this should only be used by authorized personnel who have a good reason to be opening the door.
11:01And of course, be safe around elevators.
11:04Please don't be fooling around.
11:06Be responsible and use these machines as they are intended to be used.
11:17My name's Jared.
11:18I create 3D animations to show and explain how things work.
11:21Click the cards to watch another video or click here to subscribe.
11:25Thanks for watching and I'll see you next time.