Elevator Wire Rope
The elevator wire rope has to be strong to be able to support the heavy loads that are going to be carried by the elevator. To be able to do this it has to be made from steel and have tensile strength. In addition it must be lubricated and have cross section.
The tensile strength of elevator wire rope depends on various factors. It is usually defined in terms of the nominal tensile strength of the inner and outer wires. This strength also correlates with the hardness of the wire.
The nominal tensile strength of the elevator wire rope may vary from cable diameter to cable diameter. Moreover, the nominal tensile strength is not fixed and it is determined based on the conventional values. In addition, local regulations can affect this tensile strength.
The nominal tensile strength is set within broad limits. For example, the working load limit of a rope is 20% of its nominal tensile strength. On the other hand, the breaking strength of an elevator wire rope is usually not lower than its nominal tensile strength.
Wire ropes are commonly used for hoisting in elevator cars and cranes. They are made of steel wires twisted on a central core. A rope with a steel core has a higher tensile strength and breaking force than one with a fibre core.
In recent years, steel cored wire rope has become popular for use in elevators. The tensile strength of such ropes is high, and they offer more stability. However, it requires a lubricating grease to maintain its structure. Too much grease can cause fast rope diameter shrinkage.
For safety purposes, wire ropes are typically analysed for their stress, strain and stiffness. Using special calculation software programs, high performance elevator ropes are designed.
When designing an elevator rope, it is important to consider the wire cross section. This will help to ensure that the rope can maintain its grip on the pulley. Also, it will allow you to estimate how long the rope will last.
The strand cross section of a wire rope varies depending on the size and material of the wire. Thinner wires are stronger than thicker wires. They also provide better fatigue bending properties.
Wires in steel wire ropes may have a thickness between 0.15 mm and 0.5 mm. Steel wire ropes have filler added to elevator wire rope their interior structure. These fillers reduce localized friction of individual wires.
Wire ropes are commonly used in cranes and elevators. They consist of steel wires twisted onto a central core. Various types of wire ropes have been developed for different applications. However, the most common strand construction is known as the Seale strand.
Other types of strand constructions are the Warrington-Seale strand and the Filler strand. Several studies have been performed on the impact of wire rope diameter on its life and fatigue strength.
For traction drive elevators, a rounder cross section is ideal. It offers little permanent elongation and is especially suited for elevators with large shaft heights. A six-strand rope with a fibre core should be considered when there are large undercuts in the U-groove.
Another consideration is the coating. Some pulleys have elastic coatings, which increase friction. Others have rubber-like coatings.
There are a number of different materials used to make elevator ropes. Some of these include steel wire, stainless steel, fibre, and aluminium ferrule. These can vary in price. In addition, the nominal tensile strength of the cable varies.
There are many different types of fibre cores. They are made from natural and synthetic fibres. The properties of the fibre core can influence the quality of the rope.
A fibre core is also good at absorbing grease. It is important to ensure that the correct amount of grease is applied. If the grease is not absorbed in time, it can lead to fast shrinkage of the rope. This can result in a poor service life.
When using a fibre core, it is important to use a lubricant that is suitable for the temperature range. During cooler weather, you may want to consider a solvent-based lubricant.
In addition, you should take into account the elongation capabilities of your elevator rope. The more flexible the cross section, the easier it is to adjust worn grooves. Similarly, the rounder the cross section, the less permanent elongation you will see.
One of the best ways to check the elongation of your elevator rope is to measure it against a steel wire. To do this, you will need to measure it within a single layer and offset it by 90deg.
Another measure of elongation is the length of the longest strand of the rope. As a rule of thumb, you should aim to untwist the rope maximum of 5 twists over a 100-metre shaft.
In order to prolong the life of an elevator wire rope, the lubrication must be applied in a careful and controlled manner. The right lubricant will help to prevent excessive distortion and corrosion of the wires in the rope.
The first step in lubrication is to inspect the rope. A good lubricant will coat the outside of the rope, but will not penetrate the core of the rope. It is also important to make sure that the lubricant is applied evenly across the surface of the rope.
Once the lubricant has been applied, it must be cleaned. Clean the outside of the rope with a elevator wire rope wire brush or steam cleaner. If the lubricant has been hardened, it must be cleaned with a petroleum solvent.
Depending on the type of rope and the type of lubricant, the lubrication may need to be reapplied. However, it is not necessary to perform a full relubrication. You can relubricate small portions at a time.
Specialty grease is another way to increase the life of an elevator rope. These specialty greases provide increased safety and corrosion protection. They are usually applied during the manufacturing process and continued through the entire service life of the wire rope.
Penetrating oils contain solvents that allow them to penetrate the core of the wire rope. Penetrating oils leave a heavy lubricating film on the inside of the rope, which helps to reduce wear.
Elevator wire ropes are designed to resist internal and external wear and tear. Often, they are manufactured from bright or galvanized wires. They can also be fabricated from stainless steel or alternative materials.
While there are many considerations when choosing an elevator wire rope, the type of material used is primarily the most important factor. For instance, steel wire ropes are preferred for precision stopping during loading and unloading. The price of stainless steel ropes is high, however. Similarly, galvanized wires are ideal for aggressive environments.
In addition to the price of the rope, other factors are also considered when choosing an elevator rope. For example, a good lubricant coat on the wires will help to protect the rope from corrosion. Generally, this should be applied after an extended dry period. If a lubricant is not available, solvents can be used.
Elevator wire ropes with fibre cores are capable of absorbing grease, which can be a boon for a dry lift shaft. However, this can lead to a loss in volume in the core. To avoid this problem, the strand construction should be selected carefully.
A nine-strand elevator wire rope is a good choice for traction drive elevators with a lot of deflection sheaves. It is also an excellent choice for large shaft heights.
An eight-strand rope with steel wire core is commonly used for elevators with a nominal diameter of 50 to 100 m. This offers many benefits, including a low amount of permanent elongation and little diameter reduction under load.
Elevator wire ropes have been studied in the quest to improve elevator safety. A range of studies have been undertaken to determine the life span, stiffness, plasticity, bending flexibility, and elongation of elevator ropes.
One study was to measure the smallest possible number of outer strands of a rope. For a rope with an odd number of outer strands, the smallest number of outer strands is measured over the opposite gap between strands.
This was done by examining a few different methods, including the Finite element method, the Ansys software program, and the magnetic concentration method. They concluded that there is no single standard definition of the rope elongation module.
Other studies looked at the traction between the wire and the sheave. In this case, the best method was to design a wire rope with a very narrow wire strand and a very small sheave diameter.
There are two main types of elevator ropes. These are the regular lay and the cross lay constructions. Regular lay ropes have a lower tensile elongation but offer excellent stiffness and ease of mounting. However, a slight tendency to untwist is observed when the rope hangs freely in the shaft.
On the other hand, the cross lay constructions are ideal for speed limiters, dumb waiters, and other applications where high pressure between the wires is desired. It is not, however, a suitable choice for elevator ropes.