Elevator Traction Sheave

The sheave, an important piece of elevator equipment, holds the ropes in place. Its built-in grooves allow it to keep a tight grip on the cables as they pass over it.

In traditional gearless systems, traction sheaves range from 0.6 to 1.2 meters (2-4 ft) in diameter. An electric motor drives them at 50-200 revolutions per minute.

Ropes or Belts

Typical elevator ropes are made up of several strands of wires bonded together with a fibre core. In some cases, this also means that the wires are pressed onto a metal core and are thus protected against wear. Various rope constructions are available, and they vary in terms of their breaking strength, fatigue bending properties and permanent and elastic elongation.

The optimum rope length for each application depends on the required service life of the drive machine and also on the requirements regarding the number of deflection sheaves. A drive arrangement that places the machine laterally at the top of the shaft reduces the required rope length compared to a bottom-positioned machine. This is a positive feature, as it increases the service life of the traction sheave in particular.

In addition, a high number of deflection sheaves requires the use of large diameter ropes with thick outer wires, in order to ensure sufficient frictional wear protection. These wires must be selected carefully, as they are not only subject to a high flexural stress but also have to cope with the unavoidable effect of slip.

Ropes with a steel wire core are the preferred solution for suspension ropes in medium to long shaft heights, as they have very good breaking strengths and excellent fatigue bending properties. They offer low permanent and elastic elongation and are also easy to maintain.

There are also ropes with a fibre core, which offer very high breaking strengths, but lower permanent and elastic elongation. They are ideal for a variety of applications, including slow travelling freight elevators and passenger elevators.

A special feature of these ropes is their excellent lubrication characteristics, because the fibre can absorb a high quantity of grease and then press it out of the core. However, this is a disadvantage in terms of fast rope diameter shrinkage, as a result of the increased amount of pressed out grease.

The most frequently used strand construction for elevator ropes is the 19-wire Seale strand (1-9-9), which is characterized by the thick outer wires. It offers a higher degree of resistance against external wear in use and is therefore particularly suitable for traction elevators with a high number of deflection sheaves.

Counterweight

Elevators use a counterweight to balance the weight of the car. This counterweight reduces the amount of energy required to move the elevator car upward and downward, reducing energy consumption and minimizing maintenance costs.

Counterweights are commonly made of metals such as cast iron and concreate. However, they can also be made from a few metal alloys such as steel, titanium, tungsten, and lead.

Typically, they are used to balance the weight of an elevator car and are designed for a certain maximum and minimum percent overbalance range that will meet traction requirements. These weights can be secured by bars or slugs that are attached to the frame of the elevator.

The counterweight helps provide traction between the ropes and the sheave, which is needed to pull the elevator car up and down. Without a counterweight, the car would not have any traction and the motor would have to work harder to move the elevator.

In a gearless traction machine, five to eight lengths of hoisting cable are wrapped around the drive sheave and pressed into grooves on the sheave. The combined weight of the elevator car and the counterweight pushes the cables into the grooves, providing traction as the sheave turns.

This method of traction can be used for a variety of elevator applications, including cable-hauled elevators and some kinds of movable bridges (e.g., a bascule bridge).

A traction sheave and wire rope can have many different configurations. Elevator Traction Sheave Some are double wraps, which create more traction and minimize rope wear. Others are single wraps, which have less traction and may require more maintenance.

Using a dual-wrap configuration with two sheaves can help to minimize rope wear and improve the ride quality for both geared and gearless machines. It also allows for vibration isolation pads to be added between the sheave assembly and the elevator car, which will reduce the noise that is caused by the sheave and ropes as they move together.

When a rope or groove is damaged, it can cause the elevator to lose traction and even spin out of control. This can be very dangerous and expensive to fix, especially for larger elevators that may need to travel more than 100 ft. A thin coating that is placed over the damaged part of the groove or rope can prevent this from happening.

Motor

A motor in an elevator is used to turn a sheave that raises or lowers the elevator. In gearless elevators, the motor turns the sheave directly; in geared elevators, it turns a gear train that rotates the sheave.

The traction sheave is placed in the top part of the shaft, where the hoisting ropes pass through it from one end. Alternatively, the sheave is provided with diverting pulleys that guide the ropes in a definite manner. These pulleys are typically located in parallel to each other, and are preferably placed in the same plane.

When the traction sheave is turned by the drive machine, it moves a set of hoisting ropes that are supported on the sheave by means of diverting pulleys, and the elevator car is lifted or lowered with the hoisting ropes. These pulleys are primarily used for establishing the desired suspension ratio of the elevator car and/or counterweight, but they can also be used to guide the ropes in other ways.

In this way, power is transferred from the drive machine to the elevator car and/or counterweight, without the need for a separate electric motor. Moreover, the sheave grooves in the traction sheave provide a traction force that is applied to the ropes as they are moved by the traction sheave.

As shown in Fig. 2, the traction sheave is connected to the drive machine Elevator Traction Sheave via an endless drive member. This arrangement reduces the space requirement as it only requires the installation of a single belt for the transmission between the drive machine and the traction sheave.

Furthermore, the invention allows the connection of the traction sheave to the drive machine to be monitored, so that any failures in the connection between the traction sheave and the drive machine are detected in time. The monitoring device can be a separate component or it may be located in the same enclosure as the drive machine.

For the optimum control of the drive system, it is important that the motor is perfectly tailored to the particular needs of the elevator. Only then can it achieve its full potential – and this is exactly what modern elevator technology from ZIEHL-ABEGG delivers. With the ZAdyn series of motors, for example, the drive is based on a permanent magnet synchronous gearless external rotor drive that was specially developed for traction sheave rope elevators. The motors feature high energy efficiency and low noise emissions. They are compliant with the Lift Directive 2014/33/EU and can be installed in both new constructions and as retrofits.

Controls

Elevator controls are systems that are used in elevators to control the movement of the elevator. These systems include relays, electronic components and a PLC (Programmable Logic Controller). They are all interconnected together to make the elevator run properly and safely.

The most common types of controls in elevators are key switch and nonselective collective. These are primarily used in residential elevators and allow users to choose which floor they want to go to, as well as to exit the elevator.

Destination Control – This is a more modern control system for elevators, which allows passengers to identify the floor they need to go to in the hall rather than inside the car. This helps passengers use less energy, get to their destination faster and avoid unnecessary trips, allowing the elevators to run more efficiently.

There are a few drawbacks to destination control, including that the passengers may have to wait for a certain amount of time before an elevator arrives, which can be frustrating. Furthermore, it is possible for someone to press a button twice and then have the elevator stop on that floor, making their trip more difficult.

This problem can be solved by allowing the passengers to disable these buttons if they are no longer needed. This can be done by updating the firmware on the control system and is something that could easily be added.

Some building owners prefer to use this technology for safety reasons, as it prevents people from accidentally getting stuck in an elevator. Another benefit is that it helps to improve security by reducing the number of people who can access an elevator at a given time.

In addition, it allows building owners to control which floors a person can access and when. This can be a great way to improve efficiency and safety for employees, and it can also be an effective way to monitor the traffic flow in a building.

Elevator control is an essential part of elevator operations. Having it set up correctly can lead to safer buildings and better business.