A pulley is a simple machine that lifts large objects by combining a rope or cable with a wheel and axle. Modern elevators use pulleys with large metal cables. The cable is encircled by a groove in the wheel and axle.
A Look at the Physics of Elevators
Elevators rely on the principles of physics in order to remain in motion. In this video from TED-ed, you will take a look at how the physics of elevators work. When an elevator car moves, the forces of gravity, weight, and relative motion help to keep its passengers at a stable rate.
Understanding Elevator Pulley Systems
When you install a new elevator in Salt Lake City , your technician will install a pulley system that is designed to lift the elevator car up and down the shaft safely. This video from Michael Clarke will provide you with a basic understanding of how pulley systems work.
What is an elevator pulley and how does it work?
A pulley is a device on which the system's ropes turn and can be either a deflection or a traction pulley. Divertor pulleys are divided in two categories: dead eye (with the internal structure practically closed) or spoked.
Are the pulleys certified?
No, because there is no reference standard for pulleys. Nevertheless, PFB has carried out static load tests, taking the pulleys up to their breaking load, in order to guarantee a minimum safety coefficient of 6 between the static load indicated in our catalog and the breaking load measured during the test.
Do they need maintenance?
No, it is however necessary for the maintenance technician to carry out regular checks on the wear of the pulley grooves and the correct functioning of the bearings. If one of these checks proves to be non-compliant, it is necessary to replace the pulley as soon as possible to avoid compromising the functionality of the system.
PFB pulleys
PFB fully satisfies the needs of the market, providing a wide range of pulleys in G25 cast iron with hardness HB 200 ± 20. Our range includes: divertor standard, homelift pulleys, divertor pulleys for high static load, traction pulleys, dead eyes pulleys for ropes in derogation, solid for hydraulic systems, special pulleys.
How does a hydraulic elevator work?
In this design, the passenger car (1) is supported by a direct-acting hydraulic ram (2), connected through a hydraulic pump (3) operated by a motor (4) connected to a second hydraulic ram (5) that operates a counterweight (6). As the elevator car falls, the pump transfers hydraulic fluid from one ram (2) to the other (5), so avoiding the need for a fluid reservoir. My drawing is based on a design by Otis described in US Patent 5,975,246: Hydraulically balanced elevator by Renzo Toschi, Otis Elevator Company, patented November 2, 1999.
What are the parts of an elevator?
For those of us who are more curious, the key parts of an elevator are: One or more cars (metal boxes) that rise up and down. Counterweights that balance the cars. An electric motor that hoists the cars up and down, including a braking system. (Some elevators use hydraulic mechanisms instead.) A system of strong metal cables ...
How much energy does an elevator use?
Photo: Elevators don't just hang from a single cable: there are several strong cables supporting the car in case one breaks. If the worst does happen, you'll find there's often an emergency intercom telephone you can use inside an elevator car to call for assistance.
How much energy does an elevator use to lift an elephant?
If an elevator has to lift an elephant (weighing let's say 2500 kg) a distance of maybe 20m into the air, it has to supply the elephant with 500,000 joules of extra potential energy. If it does the lift in 10 seconds, it has to work at a rate of 50,000 joules per second or 50,000 watts, which is about 20 times as much power as a typical electric toaster uses.
How long does it take an elevator to lift elephants?
Suppose the elevator is carrying elephants all day long (10 hours or 10 × 60 = 600 minutes or 10 × 60 × 60 = 36,000 seconds) and lifting for half that time (18,000 seconds). It would need a grand total of 18,000 × 50,000 = 900 million joules (900 megajoules) of energy, which is the same as 250 kilowatt hours in more familiar terms.
What is the annoying thing about elevators?
The annoying thing about elevators (if you're trying to understand them) is that their working parts are usually covered up. From the viewpoint of someone traveling from the lobby to the 18th floor, an elevator is simply a metal box with doors that close on one floor and then open again on another. For those of us who are more curious, the key parts of an elevator are:
Why is the elevator safer?
Since less force is involved, there's less strain on the cables—which makes the elevator a little bit safer.
How does a sheave work in an elevator?
The sheave is connected to an electric motor ( 2 ). When the motor turns one way, the sheave raises the elevator; when the motor turns the other way, the sheave lowers the elevator. In gearless elevators, the motor rotates the sheaves directly. In geared elevators, the motor turns a gear train that rotates the sheave.
Where is the sheave located in an elevator?
Typically, the sheave, the motor and the control system ( 1) are all housed in a machine room above the elevator shaft. The ropes that lift the car are also connected to a counterweight ( 4 ), which hangs on the other side of the sheave. The counterweight weighs about the same as the car filled to 40-percent capacity.
What is the most popular elevator?
The most popular elevator design is the roped elevator. In roped elevators, the car is raised and lowered by traction steel ropes rather than pushed from below.
When did Tom Harris write How Elevators Work?
Tom Harris "How Elevators Work" 12 February 2002.
Does a motor have to overcome friction?
Basically, the motor only has to overcome friction -- the weight on the other side does most of the work. To put it another way, the balance maintains a near constant potential energy level in the system as a whole.
Is a roped elevator more efficient than a hydraulic elevator?
Roped elevators are much more versatile than hydraulic elevators, as well as more efficient. Typically, they also have more safety systems. In the next section, we'll see how these elements work to keep you from plummeting to the ground if something goes wrong. 1 …. 3 4 5 …. Cite This!
What is an electric pulley?
An electric motor pulls the cable, lifting the car between floors. Several pulleys can be combined to reduce the necessary work to lift a load. Flag poles, cranes, and window blinds all use pulleys. Simple Machines. The Case of the Powerful Pulleys. Museum of Science and Industry: Simple Machines Game.
How does an elevator work?
In an elevator, the wheel and axle works together with a pulley to pull the metal cars to the floors above. The gears used in the elevator’s motor are also examples of a wheel and axle. A pulley is another simple machine that combines a rope or cable with a wheel and axle to lift large objects.
What is wedge in elevator?
A knife, saw, or scissors are examples of wedges. In an elevator, the braking system drives a wedge into notches on the rail the elevator car is attached to so the car stops in case of emergencies (such as cables snapping).
What is the mechanism used to trip the braking system in an elevator?
In an elevator, a lever mechanism is used to trip the braking system if the car is moving too fast. This braking system is used when the cables on pulleys break. The teeth of gears used in the electric motor that drives an elevator may also be considered levers.
What are elevators made of?
Elevators, like all complex machines, are made up of several simple machines working together. Unseen by most elevator users are the hidden parts needed for an elevator to work. These include the metal box or “car” a user rides in, counterweights for balance, an electric motor and braking system, pulleys with cables that run between the motors, ...
What is the fulcrum of an elevator?
The fulcrum is the part of the lever that the beam pushes against. If a fulcrum is close to the object being lifted, then the object can be raised with less effort than if the fulcrum was farther away. In an elevator, a lever mechanism is used to trip the braking system if the car is moving too fast.
What is a pulley?
A pulley is another simple machine that combines a rope or cable with a wheel and axle to lift large objects. Pulleys with large metal cables are used in modern elevators. The cable is wrapped around a groove in the wheel and axle. An electric motor pulls the cable, lifting the car between floors.
What is the first line of defense in elevators?
Elevators are built with several redundant safety systems that keep them in position. The first line of defense is the rope system itself. Each elevator rope is made from several lengths of steel material wound around one another.
How many ropes are needed to hold an elevator?
But elevators are built with multiple ropes (between four and eight, typically). In the unlikely event that one of the ropes snaps, the rest will hold the elevator up. Advertisement.
Do elevator cars fall to the bottom of the shaft?
Even if all of the ropes were to break, or the sheave system were to release them, it is unlikely that an elevator car would fall to the bottom of the shaft. Roped elevator cars have built-in braking systems, or safeties, that grab onto the rail when the car moves too fast.
When did Tom Harris write How Elevators Work?
Tom Harris "How Elevators Work" 12 February 2002.
Do hoist ropes snap in two?
In the world of Hollywood action movies, hoist ropes are never far from snapping in two, sending the car and its passengers hurdling down the shaft. In actuality, there is very little chance of this happening. Elevators are built with several redundant safety systems that keep them in position. The first line of defense is the rope system itself.
