It’s inevitable, a bearing will need to be replaced at some point in the life of the bearing. They do not last forever. When the time comes for a bearing to be changed, there are a few different ways to approach the removal of the old bearing.
In order to properly and safely remove a failed bearing, consider using pullers and presses that are specifically designed for that purpose. These are the best options because they save time, the damage to the shaft and housing during the process is minimized, and most of all it is safe.
A common type of mechanical removal of bearings is using two-and three-jaw mechanical pullers that pull on the outer ring evenly as the threaded post is tightened. This is centered on the end of the shaft. Heavy-duty pullers are created with hydraulic-assist rams. This allows for easy removal of the bearing.
Besides pullers and pressers, there is another type of removal tool called the separator or knife type. This tool has two plates that are placed behind the bearing.
If a bearing is being removed with a high-speed, cut-off tool, and if it is being used improperly, the housing and shaft could be damaged. Space and size limitations can dictate the necessity for this method which means that any subsequent damage such as nicks or gouges on the shaft or in the housing can result in metal removal. If any metal is removed, it can change the dimensional tolerances and the way the bearing is supposed to fit.
It is important to avoid having open flames or the making of sparks during this process if that is a possibility. Make sure to follow all of the safety guidelines in order to ensure the removal of the bearing goes smoothly and no injuries occur.
Another way to remove a bearing is to thermally remove it. This can be done by lowering or raising the temperature of shaft, housing within the prescribed limits, and/or the bearing itself.
All of the same safety guidelines for mechanically removing a bearing apply to the thermal removal of bearings as well. When thermally removing a bearing make sure that the shaft and housing are clean and clear of nicks and burrs. Before starting the project be sure to plan enough time for it.
It is important to measure and confirm that the shaft and housing are within the dimensions that are recommended. If either the housing or the shaft is not within recommended tolerances, that piece should be replaced. Using bonding agents may be a temporary fix, but bearing mounting components do not replace the important requirement of a good dimensional fit.
An important note to consider is that the use of dry ice or liquid nitrogen to bring the temperature of the steel components down, should only be used if there is an extreme interference fit. Technicians that work in northern areas during the winter tend to put large-diameter shafts outside overnight for the temperature to go down, then in the morning they heat the bearings and put them together. But be careful to avoid getting water on the steel components when leaving them outside for the night because that can lead to rust.
Both mechanical and thermal methods to remove bearings work well. It is important to follow all of the directions and safety guidelines in order for the removal of each bearing to go smoothly.
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