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Bearing NU 309 NU309 Roller Bearing Industrial Knowledge

236 Published by admin Jun 26,2026

The bearing NU 309 is a separable single-row cylindrical roller bearing widely adopted in global general and heavy mechanical transmission systems. It features a double-ribbed outer ring and rib-free inner ring, enabling full separation of inner and outer components to simplify on-site installation, disassembly and shaft maintenance. Its unified standard dimension is 45 mm bore diameter, 100 mm outer diameter and 25 mm width, achieving full cross-brand interchangeability among mainstream brands,include our own brand LLH brand.

Different from NJ and NUP series bearings, bearing NU 309 cylindrical roller bearings only bears pure radial loads without axial positioning ability, making it a standard free-end bearing for shaft systems. It flexibly compensates shaft thermal elongation, assembly deviation and running displacement to avoid axial extrusion damage. Featuring roller-raceway line contact structure, it delivers 2.5 to 3 times higher radial load capacity than same-size 6309 deep groove ball bearings.

Bearing NU 309 C3 fits high-speed high-temperature sites, and bearing NU 309 C4 applies to heavy-load mining and metallurgical machinery. Steel, brass and nylon cages are optional for cost, high-temperature resistance and low-noise demands respectively. This bearing is commonly used in industrial motors, gearboxes, water pumps, agricultural machinery and processing equipment.

For standard bearing NU 309 use, inner rings require thermal mounting below 110℃, and it must be matched with NJ309 fixed-end bearings for complete shaft axial limitation. Made of GCr15 bearing steel with HRC 60-64 hardness, bearing NU309 remains a cost-effective, durable basic component, with coated and intelligent sensing models emerging for smart manufacturing scenarios.

Structurally, bearing NU 309 cylindrical roller bearings has two retaining ribs on the outer ring while the inner ring is ribless. This separable design allows independent disassembly of inner and outer rings, greatly simplifying installation, inspection and replacement on complex shafts. A core characteristic is that it can only withstand pure radial loads and cannot bear axial force. Therefore, it is usually arranged as the floating-end bearing to absorb thermal expansion of rotating shafts and offset assembly errors, paired with NJ-type bearings to realize full axial positioning of the whole shaft system.

Bearing NU 309 cylindrical roller bearings serve as floating supports for medium-heavy load machinery. They fit industrial motors, gear reducers, water pumps, farm machinery and light metallurgical conveyors, only bearing radial loads to absorb shaft thermal expansion

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