For demanding applications requiring smooth, reliable guidance along tracks, rails, or cam profiles while supporting significant radial loads – often under harsh conditions – INA (a Schaeffler Group brand) offers a specialized range of Track Rollers, also widely known as Cam Followers or Cam Rollers. These robust components are engineered to handle combined rolling and sliding forces, impacts, and environmental challenges. This analysis delves into the design, variants (Yoke Type, Stud Type), features, and critical applications of INA track rollers.
- Core Function & Design Principle
Track rollers act as the interface between a moving machine element (like a carriage, linkage, or follower arm) and a fixed or moving track, rail, or cam. Their primary function is to guide linear or curvilinear motion while supporting substantial radial loads perpendicular to their axis of rotation, often including significant edge loads or moments.
Key Design Elements
Thick-Walled Outer Ring: The defining feature. This hardened and ground outer ring (crown) forms the rolling contact surface with the track/cam. It’s significantly thicker than a standard bearing outer ring for rigidity and load capacity.
Internal Bearing Unit: Houses the rolling elements (needle rollers or cylindrical rollers) and cage. This unit provides the low-friction rotation of the outer ring. Common internal types include:
Needle Roller Bearings: Provide high radial load capacity in a compact axial space (lower section height). Ideal for most track roller applications.
Cylindrical Roller Bearings: Offer even higher radial load capacity and rigidity, often used in extremely heavy-duty applications but have a larger axial section height.
Seal/Shields: Integral sealing (typically 2RS: double lip seals with steel washers) is standard on most INA track rollers. This is critical for excluding contaminants (dust, dirt, water, splash) and retaining lubricant, ensuring long service life in exposed environments.
Element: The method of attachment defines the main types: Stud Type (integral bolt) or Yoke Type (integral yoke for straddle mounting).
Crown Profile: The outer ring’s running surface profile is vital:
Crowned (Spherical): The most common profile. Compensates for minor misalignment between the roller axis and the track. Reduces edge stress concentration, promoting longer roller and track life. Essential for uneven tracks or imperfect mounting.
Flat: Used where alignment is precisely controlled and maximum contact area is needed on a perfectly flat track. Less tolerant of misalignment.
Special Profiles: Occasionally used for specific cam geometries.
- INA Track Roller Types: Yoke Type vs. Stud Type
The choice between Yoke Type and Stud Type hinges primarily on mounting constraints, load direction stability, and required rigidity.
- Stud Type Track Rollers (e.g., KR, KRV, KRE, KRIB, KT, KTV Series):
Design: Feature a solid, integral stud (bolt) protruding axially from one side. The stud is threaded for direct mounting into a tapped hole on the machine component or via a nut. The outer ring rotates around the fixed stud axis.
Advantages:
Compact Design: Minimal space requirement radially around the mounting point.
Simple Installation: Direct threading into a tapped hole is straightforward. Some series (e.g., KRE..-PP) feature an eccentric collar (suffix AXW) on the stud, allowing fine adjustment of the roller position relative to the track after mounting – crucial for setting preload or compensation.
Cost-Effective: Often simpler manufacturing than yoke types.
Wide Range: Available in numerous sizes, internal designs (needle/cylindrical), crown profiles (crowned/flat), and seal options.
Load Characteristics & Considerations:
Cantilever Mounting: The stud acts as a cantilever beam. This makes them sensitive to overturning moments (loads acting perpendicular to the stud axis, away from the support point).
Edge Loads: Significant edge loads or moments can cause high bending stresses in the stud and uneven load distribution on the internal bearing and outer ring.
Suitability: Best suited for applications with predominantly radial loads passing close to the mounting surface, minimizing bending moments. Avoid high edge loads or moments.
INA Track Rollers (Cam Followers) – whether the compact and versatile Stud Type (KR, KRE, KRIB, KT) or the exceptionally stable and moment-resistant Yoke Type (KRVU, KUKU, KRVPP) – are engineered solutions for reliable, high-load guidance along tracks, rails, and cam profiles. Their robust construction, featuring thick-walled crowned or flat outer rings, high-capacity internal bearings, and superior integral sealing, makes them indispensable in demanding, often harsh industrial environments. By carefully considering load types (especially moments), mounting constraints, track profile, and environmental conditions, designers can leverage INA’s extensive range and engineering excellence to select the optimal track roller, ensuring smooth operation, extended service life, and reduced downtime in applications ranging from high-speed packaging and material handling to rugged construction and agricultural equipment. INA track rollers provide the dependable, high-performance rolling interface essential for precision motion control under load.
