BEARING REMOVAL AND CLEANING

Proper bearing removal and cleaning can mean the difference between a performance and bearing failure. If done incorrectly, either procedure can damage the bearing, shaft or housing before installation even begins.

Bearing removal

There are a number of recommended tools and methods that assure safe, reliable bearing removal. Using hammers and drift pins, or an uneven application of force, for example, can cause as much damage to the shaft and housing as to the bearing itself.

Safe bearing removal tools include:

1. Arbor press;

2. Mechanical (or hydraulic) jaw-type pullers that grip parts by their press-fit edges;

3. Mechanical (or hydraulic) push-pullers that use forcing screws to push or pull parts out of the housing

4. Slide hammer pullers with a weighted sliding handle. It strikes a “stop” on its own rod and removes parts from blind holes

5. Special purpose pullers for timing gears, crankshaft sprockets, flywheel pilot bearings.

Selecting the right puller for bearing removal depends on how well the part can be gripped, how much reach and spread (height and width) are needed, and how much power or force is required. To aid in bearing removal, accessories such as extensions for jaw and cross-block pullers, attachments that split bearings, and shaft protectors are also required.

Here are some suggested methods for safe, reliable bearing removal.

Arbor press method

An arbor press applies great force, so it requires little manpower to remove bearings. It is a good method to use where one or both races have been press-fit during installation

An arbor press can be set up to:

• Support the bearing while the press forces the shaft out of the bearing, or;

• Support the shaft while the bearing is being forced off the shaft.

To remove a bearing with a press-fit inner race, first support the inner race on the press base plate with a bar or ring. Using the press, apply force only to that race. This should loosen the race and force the shaft out of the bearing. With two separable races, such as

tapered roller bearings, both races may have been press-fit and should be loosened. Never apply force to the slip fit race or the cage.

Bearing pullers

Bearing pullers should be used when the shaft is too large, obstructed or inappropriate for removal with an arbor press. Mount the puller so that the grip is firm and the puller is square with the surface. Again, apply force only through the press-fit race. The bearing should start to give and be easy to pull out of the housing. With either the bearing pullers or the arbor press, be sure to cover the parts around the bearing to prevent them from damage. Be sure to wear safety goggles to protect yourself against eye injury.

Methods not recommended

Hammering the inner race and flame heating the bearings are two commonly used, but dangerous, methods of bearing removal. The practice of hammering or prying to force removal can be costly and dangerous. The blunt force of the hammer can damage the shaft as well as the bearing. Even when a wood block is used to muffle the blow, splinters and wood chips can get into the housing and damage the bearing.

Using a torch to remove parts is even more dangerous. In addition to the possibility of igniting grease, oil or gas, the intense heat and open flame can weaken component parts and cause subsequent failures.

Cleaning bearings

Soak the bearings in a metal basket suspended in a clean container or tank holding a recommended solvent, overnight if possible. If a basket is not available, suspend the bearings with a wire or place them on a metal plate at the bottom of the container. Do not rest the bearings directly on the bottom of the bucket. (They may not clean as efficiently due to sediment on the bottom of the container.) Under ordinary conditions you can use recommended solvents for cleaning bearings. Oils heavier than SAE 10 should not be used. Gasoline or high flash point naphthas should never be used; they are flammable as well as carcinogenic (that is, they have been known to cause cancer if handled or inhaled).After dirt and grease are removed, rinse the bearings in another clean bucket of solvent. The bearings should then be thoroughly dried. The safest method is natural air-drying. Compressed air, which is free from condensed moisture, may be used to blow out the bearings, but only after all dirt and chips have been removed .If compressed air is used, do not allow bearings to spin and always wear safety glasses to protect your eyes from injury. Caution: Equipment must conform to OSHA standards.

After cleaning, inspect the bearing thoroughly for nicks, leftover dirt and damage. Inspected bearings, which are considered “good” may be used again. However, if re-assembly can not be done immediately they should be protected. Dip the cleaned bearings in a protective lubricant or coat all surfaces with a light grease. Rotate each bearing to work the grease thoroughly in and around the roller and on the races. Then wrap the bearings in waterproof paper and place each in a clean box or carton. If cartons are not available, just wrap them in waterproof paper. Mark the outside of each package to identify the bearing enclosed. Bearings which have a shield or a seal on only one side should be washed, inspected, and handled in the same manner as bearings without

shields or seals. Bearings with shields or seals on both sides should not be washed. Instead, wipe them off to keep dirt from getting inside. Smooth rotating bearings can

be coated with a protective lubricant, then wrapped and s