Special tools and bearing modifications can make removal
and installation much safer and easier for plant technicians.

Large bearings deserve extra consideration
when removing and reinstalling components
in heavy machinery. Particularly in rolling mills and
manufacturing plants where a single bearing can weigh
thousands of pounds, it is paramount to follow industry standards
for lifting bearings properly and safely. The Timken
Company repairs thousands of bearings a year for customers
worldwide and often observes damage that is attributable to
lifting and handling mistakes that could have been avoided.

The service life of any bearing depends greatly on the
care and maintenance it receives. This is especially true in
industrial applications, where operating conditions tend to
be harsh, loads are heavy, and contamination from dirt and
scale are common. Following correct lifting practices is a
critical step to ensuring long-running bearings that minimize
the cost of ownership.

Even the most experienced plant technicians and maintenance
professionals are encouraged to review the following
recommendations for lifting large bearings. Lifting standards
have changed in recent years, and legacy lifting devices may
not be as effective as some might think. Brushing up on the
basics only takes minutes and costs nothing compared to the
expense of repairing a damaged bearing.

Different Methods for Different Bearings

There are many types of bearings, and each has its own removal
process. Smaller bearings can typically be extracted
by hand or with the help of a mechanical puller device that
can be obtained from the bearing manufacturer or approved
vendor. For bearings installed with a press fit or that cannot
be removed with a puller for other reasons, often the inner
ring of the bearing can be heated to ease removal. This is
usually accomplished using a heat lamp or similar device.
(NEVER use a torch to heat the inner ring as it can alter the
properties of the bearing steel.)

Handling larger bearings requires a crane and some simple
fixtures—typically a variety of slings, hooks, chains and
mechanical devices—to safely conduct maintenance. Some
large bearings are manufactured with tapped holes in the
face of the inner or outer rings to allow eyebolts or hoist rings
to be inserted (Figure 1). Other bearings have threaded lifting
holes in the cage ring that can be used to lift the inner
ring assembly.

Thus, it is risky to assume that any one removal method
or device will work for all bearings. Always be sure of the
manufacturer’s exact requirements for lifting large bearings,
and exercise added caution when handling bearings that are
equipped with a cage, as the cage tends to be the component of the bearing that is most deformable and susceptible to
damage.

Lifting Large Bearings

Two ASME standards—BTH-1-2017 and B30.20-2018—govern
the lifting industry with concern to below-the-hook devices.
In simple terms, ASME states that a below-the-hook
lifting device is “a device used for attaching a load to a hoist.
The device may contain components such as slings, hooks,
and rigging hardware… ” Bearing lifters fall into this category.

Most heavy industrial facilities own some type of lifting
equipment, having used the same rig for decades or, in
other cases, a fabricated solution that takes advantage of
the available tooling at the plant. While these lifting fixtures
may function effectively, many such legacy or custom-built
devices may not adhere to today’s lifting standards.

Investing in a purpose-built lifting assembly is a wise
choice when it comes to large bearing maintenance, especially
in plants where several bearing lifts a week are
required. Two lifting devices are common across all industries—three-legged
fixtures and sliding-foot fixtures (Figure
2). These fixtures can be used to remove bearings from the
housing and reinstall them after completing maintenance.

Three-legged fixtures are used to lift the entire bearing
or to handle one subassembly at a time while maintaining
concentricity of the bearing components. Keep in mind that
certain fixtures may work for certain types of bearings but
not others. For instance, in an application where a bearing
changes from an open to a sealed design, there is the potential
for bearing seal damage to occur due to the length of the legs of the old fixture.

A sliding-foot fixture, meanwhile, engages the bottom
row of the bearing assembly, allowing removal of the entire
assembly at once, which can then be stacked outside the
housing, thus reducing the risk for raceway damage to occur.
This method does require ample overhead crane capacity
and the availability of machined reliefs in the chock that will
allow for the feet of the lifting fixture to properly engage the
bottom row of the bearing assembly. Hence, the use of a sliding-foot
fixture can be limited in some instances.

Bearing Features for Easy Lifting

As noted above, bearing features can make lifting individual
components much easier and safer when removal of the entire
assembly is not required. These features typically include
tapped holes in the face of the bearing race for eyebolt and
chain lifting, blind holes in the bore of the inner ring allowing
the use of turnbuckle-style lifting devices.

It is advisable to consult bearing makers directly about the
features that will provide the optimal lifting arrangement for
a given application. Depending on the bearing design, adding
lifting features may in fact compromise a bearing’s integrity.
At the same time, proper lifting practices are essential
for safe handling.

Consider what can happen when correct procedures are
not followed, where a large four-row cylindrical roller bearing
having eight tapped lifting holes in the cage (set up as
four pairs to accommodate a crossbar through the eyebolts)
is lifted using only two eyebolts, causing fracturing of the
welds that join the roller pins to the cage. This can require
the assembly to be repaired before the bearing can be used again, or where damage is severe, the assembly may even
come apart, causing components to fall to the ground.

Also, be sure to lift bearings only from a level, stationary
position to avoid potential problems. During installation, for
example, large bearings are sometimes propped at an angle
or may be resting against a table in preparation for handling.
Hence, the eyebolts may not bear the load of the lifting chain
evenly, which can result in broken eyebolts and stripped lifting
holes, creating a serious safety hazard.

A Little Care Goes a Long Way

It is critical to follow proper lifting practices for large bearings
to attain reliable operation with the lowest possible
ownership cost. Tools for lifting bearing components and
assemblies should be evaluated during the early stages of
a facility upgrade or maintenance cycle, and plant technicians
should engage bearing makers in conversation about
product modifications that can make their lives easier. With
simple planning, additional safe handling features can be
implemented before bearings are shipped and installed, saving
potentially tens of thousands of dollars for every accident
or incident avoided.