NMT Ltd.
Corporate Communications Department
Japan NMT HJ 306 EC Inner Ring Loose Rib for Cylindrical Roller Bearing, EC Optimized Rib, Bearing Steel Material
1 Model Information & Technical Parameters
Model：HJ 306 EC
Dimensions
Bore d：30 mm
Outer diameter D：44.95 mm
Rib width B：5 mm
Material & Surface Attribute
Material: Bearing steel
Coating: None
Logistics & Industry Codes
Net weight：0.042 kg
Indicative carbon footprint：0.16 kg CO₂e
eClass code：23-05-09-01
UNSPSC code：31171505
Model Description
HJ series are independent loose ribs specially designed for cylindrical roller bearings. HJ 306 EC matches NUP 306 series single row cylindrical roller bearings. It is mounted on the non-flange side of inner ring, cooperating with fixed inner ring flange to restrain rollers and realize bidirectional axial load capacity. EC stands for optimized contact profile to improve end contact condition of rollers, reduce edge stress concentration and abrasion. The loose rib is a precision ring component and must be assembled together with matched inner ring and roller assembly.
Important reminder: HJ 306 EC cannot work as bearing independently; it is only a spare part for NUP type cylindrical roller bearing maintenance. Ensure flat surface fitting during installation. Impact or collision on rib outer edge is forbidden. Deformation will lead to bearing sticking and abnormal temperature rise. Clean inner ring seating area and remove burrs and metal chips before assembly; do not mix with mismatched inner rings.
2 Structure & Operating Characteristics
Japan NMT HJ 306 EC EC optimized inner ring loose rib is precisely machined and heat-treated from high-quality bearing steel with stable hardness and contact fatigue resistance. EC optimized end profile improves contact status between roller end face and rib, relieves edge stress, reduces frictional heat and extends service life of complete bearing set.
The loose rib is a critical axial limiting component inside NUP bearings. If original rib suffers impact dent, pitting or wear deformation, HJ 306 EC can be replaced separately instead of changing the whole bearing, greatly cutting maintenance cost. The rib freely fits on inner ring journal, only undertaking axial force transmitted by rollers without radial load bearing function.
3 Core Performance Advantages
1. EC optimized contact profile alleviates roller end stress concentration, lowers friction and abrasion, suitable for continuous medium-high speed operation.
2. Fully heat-treated bearing steel with uniform hardness, outstanding contact fatigue resistance and wear resistance.
3. Dimensional accuracy consistent with original specification for direct interchange and on-site maintenance of NUP306 bearings.
4. Supplied as individual spare part; single replacement avoids waste caused by exchanging complete bearing unit.
5. Coating-free design compatible with lithium grease, circulating oil and other common industrial lubricants.
4 Matched Bearings & Application Fields
Matched bearing model
NUP 306 EC single row cylindrical roller bearing
Typical equipment
Gear reducers, industrial fans, air compressors, general motors, light conveying machinery for NUP306 bearing maintenance.
5 Assembly Specifications & Usage Guidelines
5.1 Assembly Environment & Operation Standards
Maintain clean assembly area free of metal chips and burrs. Position the rib by smooth fitting; never strike the rib body directly with heavy tools. Rotate roller assembly manually after assembly to verify smooth rotation without sticking.
5.2 Selection Guidance
Replacement loose rib for NUP 306 EC bearing → HJ 306 EC
Do not use this rib on other series NUP bearings (NUP2203, NUP205 etc.)
5.3 Lubrication Maintenance Instruction
Apply uniform grease on contact surface between rib and roller end face during assembly. Carry out lubrication maintenance together with bearing in operation cycle.
5.4 Environmental Application Notes
No anti-rust coating. Apply anti-rust oil and seal for long-term storage. For humid and corrosive working conditions, rely on bearing lubrication and housing sealing for protection.
6 Fault Identification
Typical rib failure modes: surface pitting, edge impact deformation, contact surface scuffing. Spare part replacement is mandatory once permanent deformation or extensive pitting occurs.