Important Features of Elevator Wire Rope
Important Features of Elevator Wire Rope
If you’re in need of an elevator wire rope, CED has what you need. We have a large inventory of various types of elevator wire rope, and can cut the rope to fit your exact length requirements. Call us today to order your elevator wire rope! Listed below are some important features of elevator wire rope. These features are essential for safety, as well as ease of installation and maintenance. Also, CED offers competitive pricing, so you can save money by ordering in bulk.
Description of elevator wire rope
There are two basic types of elevator wire rope. Fiber-coated wire ropes are most commonly used, but they are also available with steel cores. Fiber-coated wire ropes are easier to adjust and offer excellent resistance to contact pressure and long-term support. Steel-coated wire ropes have a metallic cross-section and reduce tensile stress on individual wires. Steel-coated ropes are most suitable for low-duty passenger elevators and slow-traveling freight elevators.
An eight-strand rope, or IWRC, has a rounder cross section than its six-strand counterpart. This type of wire rope also has less contact pressure on the groove and little or no permanent elongation. This type of wire rope is generally used in traction drive elevators with multiple deflection sheaves. The wires used in eight-strand ropes are thinner, allowing for ease of adjustment.
There are two main types of elevator wire rope: ordinary lay rope and high-tension lay rope. Regular lay ropes are easier to mount than Lang-style wire ropes, but they have lower elastic elongation and a tendency to untwist under load. Both types are widely used in elevator systems. However, it is important to note that both types are susceptible to twisting and can cause accidents. Because of this, it is important to carefully check elevator wire ropes before putting them into service.
Nominal wire rope strength is lower than the strength of crane ropes. But a rope with high strength banded force must protect traction sheaves from wear and tear. A high-strength banded forced microstructure regains 400 N/mm2 at 480 degC. Heat exposure can also reduce residual serviceability of wire. For the former, 15 to 30 minutes at 480 degC is sufficient. A wire with low strength can be permanently damaged.
There are two types of elevator wire rope. The first is called Warrington-Seale construction and is used for elevators with many sheaves that are closely positioned behind each other. This construction is not suited for elevators with differential groove depths or high-speed elevators. Warrington-Seale construction has a large contact area, so it should not be used in elevators with traction drives.
A 9-strand elevator rope is specially arranged with no wires crossing each other. This construction has minimal permanent elongation and good precision stopping. This type of rope is best suited for elevators with high shaft heights and numerous deflection sheaves. The other type is known as the single-strand rope. If you want to avoid any of these issues, you can choose a strand construction. This rope is used in elevators and dumb waiters.
Bright-colored wires are commonly used for elevator rope. Light lubricant coating on the wires is sufficient for preventing corrosion in dry lift shafts. However, light lubricant coating is not enough for outdoor elevators. In such hostile environments, galvanized wires should be used. Water-resistant lubricants should be used to relubricate elevator wire rope. Once you have decided on the wire rope, you should also consider its service life and maintenance costs.
For safety-relevant applications, wire ropes should be designed with redundancy. Redundancy means that in case of failure of an element, another will take over. Then there is the detectability. This means that the wires can be easily detected before they reach their end-of-life. The higher the degree of fatigue, the more likely they will break. A visual inspection can prevent a problem from becoming dangerous.
Cross lay constructions
The cross lay construction for elevator wire rope is similar to the strand construction for a normal rope. The outer strands of a steel wire core are placed so that they make linear contact with one another. These strands are characterized by reduced elongation and higher tensile strength than ropes made of fibre. Cross lay constructions are available in many different forms, including parallel and preceding work steps.
An 8 or 6-strand elevator wire rope has a maximum permissible number of wire breaks. The number of wire breaks is specified by ISO 4344 and can be used to assess whether a rope should be replaced or monitored more closely. If it is to remain in service, the maximum number of breaks must be studied relative to the crown of a strand. Otherwise, the strand will be destroyed and the remaining strands will be broken.
A nine-strand elevator rope uses a special arrangement of wires to minimize the risk of internal wire breaks. This type of rope features low permanent elongation, good stopping precision, and is the best choice for large shaft heights and traction drive elevators with multiple deflection sheaves. Whether it’s an elevator, a bridge, or a tunnel, a 9-strand rope is the right choice.
In contrast, a pre-formed rope is formed with reduced inner tensions. The pre-stretching process can be more intensive and require a separate work process. The maximum tensile force during pre-stretching should be about half of the minimum breaking strength of the rope. A rope that is pre-formed has low tensile strength and does not spring open with load relief.
Elevator wire ropes are structural elements made from steel wires twisted around a central core. They are tested for tensile and static loads and are commonly used for hoisting in elevator cars. There are several different types of elevator wire ropes. Each wire rope is designed for a specific application. A high-strength banded forced microstructure will regain the original strength of 400 N/mm2 after about 15 to 30 minutes at 480 degC.
The nominal tensile strength of elevator wire ropes is generally lower than that of crane ropes. The wire strength must protect the traction sheaves from wear and tear even with limited wire strength. Elevator wire ropes should have Vickers hardness HV, which is sometimes requested by elevator producers in the Far East. If the wire strength of elevator wire ropes is high enough, they will be suitable for use in heavy-duty applications.
The outer strands of elevator wire ropes are laid in parallel to prevent any damage from occurring to them. Protruding core strands may cause the rope to break. Protruding strands can also weaken the rope’s tensile strength. Luckily, EN 81-1/1998 does not address this issue anymore. The new standard focuses only on the special calculation of the rope safety factor.
The standard strand constructions are referred to as ‘cross lay constructions.’ Cross lay constructions consist of wires crossing over each other. This results in high pressure between the wires and secondary flexural stress. Such ropes are not recommended for elevator wire ropes, however they are perfectly suitable for dumb waiters and speed limiters. The following is a description of the different kinds of elevator wire ropes and their applications.
The service life of elevator wire rope is determined by the number of breaks in a strand. In six and eight-strand elevator ropes with fibre core, the maximum permissible number of wire breaks at discard is specified in ISO 4344. When inspecting an elevator wire rope, look for the number of breaks relative to the crown of a strand. The number of breaks will be larger if the rope has undergone heavy abrasion.
The appendix of this document provides a simple selection aid for the most appropriate rope type. It also describes the factors that determine the type of rope. High metallic cross-section is not a requirement in every installation. Low price often does not satisfy all requirements. In such cases, it is important to choose a rope that is made of high-quality core material. As the height of an elevator shaft increases, the elongation rate of the rope also increases.
The eight-strand rope with a fibre core is a universal type that is used in most elevators. It is a high-grade, medium-priced option that has excellent fatigue bending characteristics. Its diameter is smaller than six-x-19 but has higher breaking load relative to its diameter. It is commonly used in elevators of 50-100 m. It is recommended for a range of applications including high-duty elevators.