Elevator Wire Rope Maintenance
Elevator Wire Rope Maintenance
Evaluating the performance of elevator wire ropes is critical to maintaining the smooth running of an elevator. This article discusses the various aspects of rope maintenance, including inspection of elevator wire ropes, the impact of vibrations on the rope, and the rotation of the rope. Whether an elevator wire rope is a fiber core or independent wire rope construction will depend on the specific situation. However, you should also make note of the apt dimensions of wire ropes before installation.
Inspection of elevator wire rope
The Inspection of Elevator Wire Rope is the responsibility of the maintenance personnel. This process helps determine whether a wire rope is beyond repair or needs replacement. It also outlines the conditions that warrant such inspection. The inspector should follow the applicable standards when inspecting the rope. Broken wires should be repaired or removed from service. The inspection frequency must be determined by a qualified person based on several factors including the amount of traction load, expected rope life, and the severity of the environment.
Corrosion is more difficult to evaluate than abrasion. It is more severe than abrasion, but often occurs internally, before the outer evidence is visible. Even slight rusting may signal that a wire strand needs lubrication. Severe corrosion can lead to premature failure of the wires and strands and should be replaced as soon as possible. However, if you discover signs of excessive corrosion, you should contact your elevator maintenance service provider for assistance.
Fortunately, the industry has established guidelines for inspection. ASME A17.1/CSA B44 section 8 and other regulatory sources now include inspection terms for elevator wire ropes. The safety standards define the permissible diameter reduction for eight-mm and larger ropes. Under certain conditions, ropes may reduce by up to six percent. Under “unfavorable wear,” the percentage of crown wire breaks is reduced to a half. For more information, see “General Notes” in Table 126.96.36.199-1.
When performing an inspection of elevator wire rope, use a portable or handheld wire rope tester. This portable inspection device can be used for multiple targets and provides quantitative and qualitative data. It can inspect both high-speed and normal-speed elevator wire rope arrays. The tester is computer-assisted and features a built-in database of history track records. In addition to its portability, TST Portable Elevator Wire Rope Tester can generate inspection reports onsite, and has a large built-in database for recording test results.
When wire rope fails, it is crucial to replace it. Besides preventing damage from occurring, it is also required to inspect it for safety reasons. A faulty wire rope will result in dangerous operating conditions. If it breaks, the rope will be unable to support its own weight. In addition to its lifespan, a poorly maintained wire rope will not function efficiently. Therefore, regular inspections should be performed for this purpose. For this purpose, it is important to inspect elevator wire rope on a regular basis.
Impact of vibrations on the rope
An elevator’s wire rope is susceptible to vibrations, but it is not completely immune. A recent study of a steel wire rope in a large elevator has revealed that it is highly resilient to vibrations. Vibrations of elevator wire ropes are the result of a combination of various factors, including the elongation module, the length, and the tensile strength. These factors all contribute to the strength of elevator wire ropes, but the impact of vibrations on these components is the most significant.
While the effects of vibrations on the transverse and longitudinal axes of an elevator are quite different, these two modes of motion are similar. While the transverse and longitudinal axes of vibrations have similar characteristics, the latter is enhanced in amplitude by a larger amount. At the 23.6 Hz excitation frequency, the transverse amplitude enhancement is slight. With increasing the excitation frequency, the amplitude enhancement becomes stronger, but the longitudinal axis no longer exhibits a symmetrical distribution.
In addition to the above, the ropes may rotate and impact each other in an elevator’s 2:1 suspension system. This is not necessarily a sign of a lower service life, but it can produce a perceptible noise that passengers can hear. Despite the fact that the elevator’s deflection sheaves are not rotating in their central axis, the impact on elevator wire rope is still significant.
Another important issue is the impact of wind vibrations on the wire rope. In some cases, wind-induced vibrations can cause the steel wire to fatigue and eventually break. This is not the case with all ropes, however. Despite this, elevators often encounter vibrations that are too high to be eliminated by friction. However, in some cases, the vibrations are so high that the elevator rope has no other option but to change the design.
When compared to the high-speed elevators, vibrations in the container can cause physical discomfort for passengers and damage delicate equipment. In addition, vibrations from the container cause the rope to vibrate, which will also cause vibrations in the connected rope. These vibrations will reduce the effectiveness of the traction friction pulley. The resulting vibrations can cause severe damage to both the rope and the building itself.
Fiber core versus independent wire rope core construction
There are several differences between independent and fiber cores in elevator wire rope. Independent cores offer higher strength, better resistance to crushing, and greater bending fatigue life. However, the benefits of fiber cores outweigh the downsides, and you should use them only when needed. Here are some tips to help you decide which type is right for your elevator wire rope. Fiber cores are more flexible than independent cores, and are less likely to crush.
The major difference between fiber and steel-core elevator ropes lies in the direction of the twist. The inside wires of a fiber rope lie parallel to the axis. This increases their resistance to fatigue. Both types of cores have different benefits. Typically, steel cores are preferred for use in high-temperature environments. These ropes can be galvanized or stainless steel.
Both wire rope types have their advantages. Fiber-core elevator wire ropes are more flexible and have less elongation, while steel wire-core elevator ropes are less elastic and tend to have shorter service lives. However, steel wire core ropes require much less support, which may be an important consideration for your elevator wire rope. If you’re not sure which is best for your elevator wire rope, take the time to assess the application of different types.
In the elevator industry, there is no standard wire-core construction. There is a range of variations in shaft height, car suspensions, and counterweights, which require different rope constructions. Then there are the high-speed installations, which require tensioned balance ropes and overspeed governor devices. And, of course, there are the nuances of traction drive elevator wire rope, which often demand different kinds of rope construction.
Both types of wire rope can have a steel core. While fiber cores provide more flexibility and greater strength, steel cores are better for operations where a fiber core may not be enough. Furthermore, steel wire cores can handle operating temperatures over 180 degrees F. Steel cores can also be made in many different shapes and sizes, which will enhance the strength of the elevator wire rope. Depending on the type of core, it can be used in a wide range of applications.
Rotation of the rope
The service life of elevator wire rope is highly dependent on its traction capability, but the installation conditions also play an important role. In the right-hand illustration, a full steel rope with six, eight, or nine outer strands is installed in undercut U-grooves that have extreme undercut angles of 105deg. The rope cross-section on the right-hand illustration shows the fixed centre point of the rope and the rotating cross-section.
The main advantages of the 8-strand rope construction for elevators are low maintenance and high breaking load relative to diameter. It also features little permanent elongation. Its optimum performance is found in elevators with large shaft heights and low-speed, high-capacity traction, and high traffic flow. However, this rope is not suited for all applications. High-speed elevators often use ropes with a Warrington-Seale core.
Besides the design considerations, the safety performance of the elevator wire rope is also an important factor. It is crucial to select a high-performance rope, since simple rope constructions are no longer suitable for high-rise installations. All the rope constructions shown in Fig. 13 are special ropes. Their elongation under load will affect the deflection of an elevator car. The load is directly proportional to the rope’s elongation module, which must be calculated with respect to elevator safety factors.
The elongation module describes the elongation behavior of steel wire ropes in the longitudinal direction. It is derived from a static tension testing procedure. It is nonlinear, and is dependent on several parameters, such as rope construction and core. It also depends on the use of the rope and the manner in which it is handled. It is important to avoid unnecessary twists in the steel wire rope. However, there are no definite guidelines for its elongation module, and it is largely a case of using the right technique.
One of the key components of an anti-rotation device is an anti-rotation cable 360. This cable is threaded through anti-rotation devices 350 attached to the top and bottom of the cable shackle 320. In addition, the anti-rotation device is placed in the mechanical room. As with any other anti-rotation device, the cable can rotate in some degrees. However, it is highly unlikely that it will rotate in full 360 degrees.