Cam followers are specialized bearings that are supported from a single point on their circumference. On the point of contact, singular roller forces create a bending of the outer ring. This bending creates an outer ring deformation with reversed bending stresses in dynamic applications, a decreased load zone, and a higher maximum roller load. In attempts to minimize deformation, cam followers need to include a heavier cross-section than a standard bearing. This requirement conflicts with the need for maximum dynamic bearing capacity which calls for the largest roller diameter possible.
Video Credit: Emerson Power Transmission Solutions
Needle roller cam followers are used in a wide range of linear motion systems. These cam followers are equipped with the necessary heavy-duty, outer ring cross-section. They also include complementary needle rollers. Needle rollers are designed to be compact while providing a stable load carrying capacity and anti-friction performance.
One type of heavy-duty needle rollers is the “yoke-type”. The yoke-type design is used when loading conditions exceed the abilities of regular stud-type cam followers, or where clevis mounting is useful. Clevis mounting accommodates support on both sides of the cam follower and grants use of a high-strength pin. Yoke-type cam followers can be purchased with or without seals and crowned outer rings.
Caged roller followers are cam followers which provide increased internal grease-storage to assist with infrequent re-lubrication. Caged rollers permit operation at high loads and speeds, much like when using the heavy outer-ring cross-section. Much like the yoke-type, caged roller followers are available with and without seals.When mounted, caged roller followers normally placed directly on a hardened ground pin.
Bearing Surface Configuration
Crowned Outer Rings
The purpose of having crowned outer rings is to minimize outer-ring thrusting in applications where the axis of the cam follower is unparallel to the surface of the track or is skewed in relation to the direction of travel. For this reason, crowned outer rings are an ideal selection for use with curved or circular tracks; however, in well-aligned applications, crowned outer rings can contribute to rapid track wear.
The unsealed design provides decreased friction, which assists with the prevention of skidding in lightly loaded applications and flow-through lubrication.
Cam followers come in a variety of designs with specialized options. These options include re-lubrication with built-in grease fittings, an integral threaded-stud mounting option, crowned outer rings to handle misalignment, additional stud strength for high-shock loading, and corrosion resistance for food processing and pharmaceutical applications. Before choosing cam followers, it is important to consider these options.
ABMA STD 13411 - Aerospace - airframe needle roller, cylindrical roller and track bearings - technical specification
ABMA STD 13412 - Aerospace - airframe needle track roller, yoke type, single-row sealed, inch series
ABMA STD 13413 - Aerospace - airframe needle track roller, yoke type, double-row sealed, inch series