Elevator Wire Rope Construction
The elevator wire rope is an essential component in traction drive elevators. Its optimum performance depends on the design of the strands and the core material, as well as the use of appropriate lubricants.
Elevator ropes should be inspected regularly in order to determine their remaining service life or to change them when necessary. They should be stored in a dry, frost-free and dust-free environment.
The construction of a wire rope is important because it can have a major impact on strength, flexibility, fatigue life and torque resistance. It is a significant factor in determining the performance of your elevator wire rope, aircraft cable, or wire rope.
Strands (wires laid together in the finished rope) are designated by their outside diameter and number of wires per strand. The design arrangement of the strands is called a “construction.” The most common strand constructions are Ordinary, Scale, Warrington and Filler (fig. 5-2).
In addition to ordinary strand constructions, there are strand constructions that are made from multiple wires or fibre cores in each strand. These constructions are known as “multiwire” or “fibre core” strands.
A standard strand construction has the wires in a strand cross-laying over each other. This leads to an increase in contact between the wires and a higher level of flexural stress, which can lead to internal wire breaks.
Due to the increased wear and risk of wire break nests, this type of strand construction is usually found only in thin ropes for dumb waiters, speed limiters and other low-speed applications. However, the high tensile strength and stiffness of this strand construction makes it an excellent choice for large elevators that require a heavy load capacity, particularly in traction drive elevators.
In addition to a high number of strands, full steel ropes also offer the advantage of having a more flexible structure and better fatigue bending characteristics. This makes it an ideal choice for traction drive elevators with a large shaft height and a large number of deflection sheaves.
STEEL WIRE CORE
Steel wire ropes are used in most industries for a number of reasons. They offer superior strength, durability, and safety in many applications. In addition, they are incredibly versatile in their use and can handle a wide range of jobs, making them a cost-effective choice for most projects.
The optimum design of an elevator wire rope depends on a few important factors, including the material it is made from and the structure of the rope itself. One of the most significant aspects is the type of core used.
A core can be made of either natural or synthetic fibres. The latter option is preferable in environments that require a high degree of flexibility and resistance to fatigue over time.
Another consideration is the resistance elevator wire rope to crushing. This is important for environments such as the mining industry.
Generally, the more wires that are in a rope, the more resistant it is to breaking. The strand construction of the rope can also have a major influence on this aspect.
The most commonly used strand construction for elevator ropes is the 19-wire Seale strand (strand: 1-9-9). Its thick outer wires provide good resistance against external wear when running over the traction sheave and deflection points.
It is also recommended to use a filler strand when the rope diameter is over 16 mm (5/8″), because it offers improved flexibility and is more resistant to fatigue bending tests.
The elongation factor of an elevator wire rope is also another important factor to consider. It is a measure of how much a wire rope will stretch over the course of its service life. This can vary greatly depending on the strand and rope construction, as well as the load conditions.
The fiber core in an elevator wire rope provides support for the outer strands and keeps the wires in place. Fibre cores are also used to ensure that a rope is flexible and resists fatigue over time. They are best suited to applications that require flexibility and where the temperature may exceed 180 deg F.
The optimum type of fiber core depends on the application. The most common fiber core for elevator ropes is a fibre core (FC), which is made of natural or synthetic fibres. This type of core has a high degree of flexibility and makes the rope more easily adjustable up to the groove shape.
Another option is an independent wire rope core, which is a steel core wrapped around the strands. This type of core reduces tensile stress in the individual wires and increases the metallic cross-section of the elevator rope.
As a result, the elongation of elevator ropes can be reduced. This is particularly important for slow-moving freight elevators, which must be able to accommodate large loads without breaking.
In some cases, a higher tensile strength in the outer strands can be achieved by means of a suitable pre-stretching process, which involves a separate work process. However, this requires more intensive measures than the stranding process described here.
A relubrication of an elevator rope is necessary from time to time in order to avoid the development of cracks and other damages in the outer strands. The use of lubricants with solvents is recommended. These should be applied to the rope from the outside in such a way that they penetrate the fibre core as well.
An elevator wire rope is an extremely complex mechanical device that consists of numerous moving parts that work together to support and move loads. As such, there are a number of different specifications and properties that can affect its performance and service life.
One of the most important factors that affects the performance and service life of an elevator wire rope is the filler standard used in the manufacturing process. The filler standard is designed to help improve the bending fatigue of the rope by reducing wear and damage internally and externally.
The filler standard is usually made from a matrix of plastic, which is then impregnated into the internal spaces between the strands and wires. This helps to reduce abrasion and protects the wires from corrosion, which can cause serious injury in certain elevator applications.
In addition to the filler standard, an elevator wire rope can also have a plastic coating applied to its exterior surface to help protect the rope from abrasion and other environmental factors that may cause corrosion. This can be a great advantage in certain applications, but it can also make it difficult to inspect the individual strands and wires.
Lastly, an elevator wire rope can have a pre-stretching effect applied during the stranding process to help it spool more uniformly on the drum and help to increase its flexibility. This type of stretching is often done by applying load to the wires and strands while they are still being stranded, which can be accomplished in several ways.
An elevator wire rope can also be manufactured with a variety of different constructions that are used to meet the specific elevator wire rope needs of different applications. This includes traction drive elevators, roped hydraulic elevators, dumb waiters, car suspensions and counterweights, and overspeed governor devices, among other things.
Filler materials play an important role in many constructions. Adding them to concrete, composite materials, and plastics can reduce the usage of expensive binder materials. They can also improve the processing properties of the respective material.
For example, gravel, stone, and sand are used as filler materials in concrete. They reduce the usage of cement and improve the volume and tenacity of the concrete. Cardboard is also a common filler in dry wall partitions. Saw dust is used in particle board.
Elevator ropes are often discarded due to wire breaks, wear-and-tear, or diameter reduction. These factors have a negative impact on the service life of the elevator wire rope and can even lead to the development of vibrations in the rope.
To avoid this, the strands of an elevator wire rope are pre-stretched during production. Experienced manufacturers use suitable procedures to achieve this.
Besides, the outer wires of an elevator wire rope are regularly checked for signs of abrasion. Those wires which show heavy signs of abrasion are likely to break in relatively quick succession.
It is therefore possible to determine the residual service life of an elevator wire rope with relative ease. This can be done using the strand breaks in the elevator wire rope as a reference point.
It is also possible to estimate a maximum service life of an elevator wire rope by measuring the strand breaks and their distribution. The service life of an elevator wire rope can be influenced by the type and quality of the strand breaks, as well as the conditions in which the elevator is installed.