Elevator Traction Sheave
In traditional gearless traction systems, an electric motor drives a large drive sheave, turning it at 50 to 200 revolutions per minute. The hoisting ropes wrapped around the drive sheave pull the elevator car and counterweight up and down in the shaft.
While the ropes are not subject to as much wear as the sheave, it is important that they stay in good condition and the tensions between the ropes be balanced. Having herave grooves regularly inspected can ensure that tension is still balanced and that the grooves fit properly on the cables.
Benefits
An Elevator Traction Sheave is an important component of any elevator. These sheaves are used to lift a car up and down, as well as control the elevator’s speed. The sheave can be a gearless or geared unit, and is typically housed in a machine room above the elevator shaft.
Sheaves are often rated for a certain amount of wear before they need to be replaced. Having a trusted professional elevator technician inspect your sheaves at least annually can help ensure your sheaves remain in good condition, and will let you know if regrooving is an option or if a replacement is necessary.
One of the main reasons why sheave wear occurs is due to the tension between the ropes. If the tension is not balanced, it can cause damage to both the sheave and the ropes.
To equalize this tension, the traction sheave uses a spring that slips when the difference between the traction friction force and the equalizing spring force exceeds a specific value. This causes the ropes to move further per rotation of the sheave than the damaged rope/groove, causing them to “slack off” and “equalize.”
The problem is that this movement grinds the sheave material as shown in Figure 1. Sheave material can be expensive to replace, so ensuring your elevator sheaves are properly maintained is key to keeping your elevator in good condition.
A common type of traction sheave used in elevators is made from cast iron. However, there are other sheave types that use steel or brass.
Some elevator manufacturers have also started using flat steel belts instead of traditional ropes. These belts are light, durable, and do not require any oil or lubricant. They can also cut energy costs for buildings and are a great alternative to steel ropes.
The majority of traction sheave elevators use steel wire ropes, and these can be hard on the sheave over time. The sheave’s material may also be affected by wear, so it is essential that elevator sheaves be inspected regularly to ensure they are in good condition.
Installation
An elevator traction sheave is an essential part of an elevator’s operation. Sheaves must be inspected and maintained regularly to ensure that they continue functioning properly and safely. Without this maintenance, sheave damage can occur, leading to inefficient and unsafe operations.
Elevator sheaves are located in the top of an elevator shaft and can either be gearless or geared. Either way, the sheave rotates with the help of an electric motor (2), which raises or lowers the elevator.
Sheaves can be made of steel, brass, or other materials. The sheave’s shape is important, as it determines the sheave’s tractive force and how the rope and sheave interact with each other.
The sheave’s shape and construction also affect the type Elevator Traction Sheave of lubricant that should be used to keep the sheave clean. Different types of lubricants are suitable for sheave wear, so an expert should be consulted before deciding which lubricant is best for the sheave’s specific needs.
In general, a lubricant that is thin and evenly spread throughout the sheave will work best for most sheaves. This is because it will allow the sheave to rotate with minimal friction, resulting in less wear on the sheave and less overall cost for the elevator.
Another consideration is the type of rope that the sheave’s strands are made of. The sheave’s strands should be designed to handle the complex stresses that they will encounter when traveling over the sheave.
Typically, elevator traction sheaves have a round cross-section, meaning that they are able to withstand a great amount of pressure. However, this also means that they are prone to wear, which is why the sheave’s design must be carefully considered.
Traction sheaves are made of various materials, including stainless steel, bronze, and cast iron. Stainless steel is the preferred material due to its durability and ability to resist corrosion. Regardless of the material, a high-quality sheave is essential to ensure that the sheave lasts as long as possible.
Because sheave construction is so important to the elevator’s safety and efficiency, it is imperative to have a trusted technician inspect the sheave before determining whether regrooving is needed. Depending on the damage, an elevator technician may recommend other repair or replacement options. By following their recommendations and having the sheave inspected, you can be sure that your elevator will remain safe and efficient for years to come.
Maintenance
The Elevator Traction Sheave is one of the most critical and central components in traction elevators. Without it, elevators can become dangerous to operate and passengers may be at risk of injury. Having an experienced technician regularly inspect and service your elevator sheaves will ensure that they are in top working condition, allowing them to continue safely transporting passengers throughout your building.
The sheave is connected to an electric motor, which turns it either one way or the other, thereby raising and lowering the elevator. In gearless elevators, the sheave is rotated directly by the motor; in geared elevators, it is turned by a gear train. The sheave, motor and control system are typically housed in a machine room under the elevator shaft.
There are several components within the elevator hoistway that also require routine maintenance, including guide shoes and oil buffers. These parts can be damaged from exposure to water or other contaminants and require routine cleaning and painting as well as oil changes if they are exposed to floods.
Depending on the type Elevator Traction Sheave and age of your elevator, it can be necessary to replace the guide shoes or the oil buffers if they are worn down or damaged. This can be done on-site or at a machine shop.
Another common part of the hoistway that requires frequent maintenance is the elevator brake. A brake is a spring-loaded clamping device that prevents the elevator from moving when the car is at rest or the hoistway motor is not in operation.
Once an elevator brake has been replaced, it is imperative to keep it clean and properly maintained to ensure that it performs at its peak capacity for the longest possible period of time. A regular and thorough inspection of the brake should be performed by a professional technician to identify any damage that has occurred, which can then be repaired or replaced as needed.
Other sheave components that need attention include the girders, pulleys and worm gears. These parts can be inspected and maintained on-site or at a machine shop by a qualified elevator technician.
Replacement
The Elevator Traction Sheave is one of the most important components in an elevator system. The sheave supports the hoist rope, which is used to raise or lower the elevator car, and also acts as a braking mechanism.
The sheave is positioned in the shaft of the elevator and connected to the drive motor by a hoist rope or by a suspension rope. The hoist ropes pass through the sheave groove and are supported by the sheave liner.
Sheave liners are typically made of a rubber-like material, and they provide the necessary traction between the sheave and the hoist ropes. However, they wear down over time and must be replaced.
As a result, the replacement process for sheave liners can be expensive and time-consuming. It can take a specialized repair crew as many as three days to replace each sheave liner on an elevator system.
The present invention significantly reduces the time that an elevator system must be out of service. This is done by eliminating the need to remove the elevator car from the drive sheave and rehang it after the sheave liner replacement procedure is complete.
This new method of replacing a sheave liner can be accomplished much faster than the previous methods and can be performed by a single repair person. In addition, the procedure does not require removing the elevator car from the hoist ropes, which eliminates the time-consuming and labor intensive task of readjusting the hoist ropes.
Another advantage of the present invention is that it reduces the amount of damage to the sheave groove. Sheave grooves have a tendency to become worn and erode over time, particularly when they are exposed to high temperatures. The present method involves running the drive sheave at low speeds and holding onto a rotating liner end that is being pulled in between the rope and the sheave groove.
The sheave liner is then rotated into the proper position within the sheave groove, and it is joined to a first new liner end and to a second new liner end while the elevator car is suspended from the hoist ropes that are supported by the sheave liner. As the elevator car is lowered or raised, it is suspended on the hoist ropes and moves along car guide rails until it reaches an anchorage at the top of the shaft of the elevator.
