FAQs Part 8: Identifying and Measuring Bearings

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To Begin: Please fill out our Conveyor Roller Quote Form and a Heinrich Brothers representative will contact you. For more immediate help, call us at 724-969-1188.

How Do You Identify Bearings?

First, please let us know the following:

  • Do you have a specific bearing you would like to use?
  • What are the markings on the bearing? (For example: model #, mfr name…)
  • Is there a category description below that matches your type of bearing?
  • Do you have any preferences to features or applications?

What are the Bearing Options?

Sealed: On non-precision bearings, a seal can be detected if the balls are covered and a plastic/rubber “wall” can be seen through the inner and outer races. Semi-Precision and Precision bearings with seals will have a plastic/rubber cover over the balls between the inner and outer races.

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Shielded: A bearing with shields will have a metal cover over the balls between the inner and outer races.

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Grease Packed: Often times grease packed bearings can be identified by the grease coming out between the races. Grease Packed bearings do not rotate as easily as a free-spinning oiled bearings because of the increased rolling resistance the grease creates.

Oiled: An oiled bearing, when spun, will spin for an extended amount of time compared to a grease-packed bearing. Oiled bearings are typically used in gravity applications because they require less energy to move than grease packed bearings.

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Regreasable Bearings: If the axle is missing, regreaseable bearings can be identified by the holes through the inner race that allow grease to be directed into the bearing.

If the axle is intact, it will have a regrease zerk fitting on the end. If the roller contains regreasable bearings, it is important to note the frame thickness of the conveyor in order to line up the regreasing holes (zerk fittings) on the axle. You must use calipers to measure the frame thickness if the frame thickness (measured in gauge) is unknown. Measure to the nearest 0.001″.

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What are the Bearing Types?

Unground (Non-Precision) Bearings: Unground or Non-Precision Bearings have stamped metal housings with very loose tolerances. If the bearing is not shielded or sealed, sometimes the balls can be seen between the inner and outer races. Unground bearings can be crimped or press fit. If crimped, they are non-replaceable.

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Semi-Precision Bearings: The Semi-Precision Bearing has machined metal raceways with tighter tolerances than unground bearings. The raceways can be made from mild steel, stainless steel, or polypropylene. All bearings in this category are pressed into tubes and can be replaced.

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ABEC Precision Bearings: The ABEC precision bearing has ground and polished raceways made from hardened chrome steel. ABEC bearings have many styles. The most common styles are:

Polypropylene Housed Bearings: These bearings consist of a radial ABEC bearing inside a polypropylene housing assembly, typically black. The housing must be crimped into the tube which means they are not replaceable.

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“All Metal” ABEC Bearings: These bearing feature hex bores, extended inner races, and flanges. They have metal shields and rubber contact seals on both sides of the bearing.

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Agricultural Bearings: These bearings are heavily sealed ABEC bearings, which are designed for use in agricultural equipment. They are available with hex bores and square bores. They are also available with both spherical and cylindrical body shapes.

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Insert (Set screw) Bearings: These bearings have oversized round bores. The inner race is extended and features set-screws, or some other mechanism, that locks the inner race to the axle. They are available with both spherical and cylindrical body shapes.

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What are Bearing Assemblies?

Adapter Bearings: are bearings pressed into a stamped metal adapter. Standard adapter assemblies must all be crimped into tubes.

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Sleeve Bearings: Large ABEC bearings, either Insert bearings or Agricultural bearings, with spherical body shapes, cannot be installed directly into a tube alone. They must have a sleeve. The sleeve is a machined piece of steel with a spherical inner diameter that the bearing can be installed into.

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Plastic Bearings: The bodies of the bearings are molded plastic, usually Acetal (Delrin). The balls are 420 stainless steel. These bearings usually come in various colors.

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Bushings (Roll End Bearings): These bearings are solid pieces of material with NO rolling elements and NO moving parts.
These bearings are commonly made of:

  • UHMW
  • Hardwood
  • Teflon
  • Nylon
  • Polypropylene
  • Acetal (Delrin)
  • Bushings (Roll End Bearings)

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Framesaver Bearings with Axle: Framesaver Cartridges consist of two radial ABEC bearings and a spring loaded stub axle in a polypropylene housing. When installed in a roller, they do not require a thru axle. Use the picture to help identify framesavers. It can be difficult otherwise to know for sure it is a framesaver unless the roller is cut to show no thru axle. As shown in the picture, it is also available with a plastic hex sleeve.

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How do I Measure Bearing Dimensions?

If unable to identify the bearing, measure the appropriate dimensions.

  • Place the angles or straight edges against the front face of the bearings.
  • Using calipers, measure between the angle or straight edge and edge of tube to determine the bearing extension.
  • Measure to the nearest 0.001″.

If the roller can be taken apart and the bearing can be removed from the tube, use calipers to measure the outer body diameter (OD), similar to the tube OD.

  • Use calipers to measure the flange OD, similar to the tube and bearing body OD.
  • Use caliper depth gauge to measure the length of the bearing through the bore.
  • Identify the bore shape to determine if it is a hex or round axle bore. Measure the bore to determine the axle size for that bearing.
  • For round axles, measure the diameter.
  • For hex axles, measure the distance across the flats.

How do I Determine the Bearing Material?

Use a magnet on the bearings to identify if the material is steel. If the bearing is magnetic it is steel. Hold the magnet by the face of the bearing to stay as far away from the bearing balls as possible to ensure the magnet is not attracted to the balls. Bearing balls can sometimes be made from high quality 420 Stainless Steel which can have magnetic properties.