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Rex BMF5215S 2-15/16" bore mounted spherical roller bearing in a fixed cast iron 4-bolt square flange block with pilot. Part of the 5000 heavy duty series, it features a double setscrew locking collar and a spring-loaded heavy contact lip seal. This unit includes one closed auxiliary cap and is designed for high-load industrial applications.
MODEL 10407321
Contact supplier for technical support on: 800-626-2120
$1,330.90 Each
Prices are subject to change
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Typically Ships in: 1 day
Returnable: See conditions
Ability to Relubricate
Yes
Auxiliary cap kit
A9215; B9
Auxiliary Cap Kit
A9215; B9
Auxiliary seals
1 open 1 closed cap cast iron
Auxiliary Seals
1 OPEN 1 CLOSED CAP CAST IRON
Available Seal Type
K Light Contact Lip Seal; M Spring Loaded Heavy Contact Lip Seal (Buna and Viton); Z Clearance Seal; G Triple Lip
Bearing Brand
REX ROLLER BEARING
Bolt circle radius (in)
4 1/4 in
Bolt Circle Radius (in)
4 1/4 in
Bolt Size (in)
2.9375 in
Bore length (in)
4 7/8 in
Bore Length (in)
4 7/8 in
Bore size (in)
2.9375 in
Bore Size (in)
2.9375 in
Cage Material
Engineered Polymer
Clearance
C3 STANDARD
Distance between bolt holes (in)
6 1/64 in
Distance Between Bolt Holes (in)
6 1/64 in
Fixed vs. Expansion
Fixed
Foot Height (in)
0.88
Grease Fitting Thread Size
1/8 NPT
Height
9.88
Housing Cast Face to Outermost Bearing Face (in)
0.88
Housing coating
Powder coated
Housing Coating
POWDER COATED
Housing construction
Solid
Housing Construction
Solid
Housing material
Cast iron
Housing Material
Cast Iron
Housing style
Flange block
Housing Style
Flange Block
Housing type
Flange, Four Bolt, Pilot
Housing Type
Flange, Four Bolt, Pilot
Housing width (in)
7 3/4 in
Housing Width (in)
7 3/4 in
Inner Ring Outside Diameter (in)
3.37
Insert
5215U
Length
10.00
Length Through Bore (in)
4.88
Locking collar outside diameter (in)
4 1/16 in
Locking Collar Outside Diameter (in)
4 1/16 in
Locking device kit
SC9 QTY 2
Locking Device Kit
SC9 QTY 2
Locking Type
Double Set Collar
Lubrication type
EXXON RONEX MP STD
Lubrication Type
EXXON RONEX MP STD
Maximum Speed (RPM)
1700 rpm
Maximum Temperature (C)
107 C
Maximum Temperature (F)
225 F
Microlock kit
ML3
Microlock Kit
ML3
Misalignment Capability
±2.0° Misalignment - Dynamic
Misalignment Type
Dynamic
Mounting bolt size (in)
3/4 in
Mounting Bolt Size (in)
3/4 in
Mounting pad height (in)
7/8 in
Mounting Pad Height (in)
7/8 in
Net Weight
33.00
Overall Height to End Cap (in)
7
Overall Length (in)
7.75
Overall width
7.75
Pilot diameter (in)
6.3125 in
Pilot Diameter (in)
6.3125 in
Primary seal
Buna spring loaded lip seal
Primary Seal
BUNA SPRING LOADED LIP SEAL
Radial Dynamic Load Capacity (lb)
57750 lb
Radial Static Load Capacity (lb)
71500 lb
Retainer material
Engineered Polymer
Retainer Material
Engineered Polymer
Rolling element
Spherical Roller
Seal kit
MS9
Seal Kit
MS9
Seal type
Heavy Contact Seal
Seal Type
Heavy Contact Seal
Setscrew torque (in-lbs)
680 in/lbs
Setscrew Torque (in-lbs)
680 in/lbs
Size code
9
Size Code
9
Unit of dimension
in
Unit of Dimension
IN
Vibration frequency fundamental train
0.0072 cps
Vibration Frequency Fundamental Train
0.0072 cps
Vibration frequency inner ring defect
0.1701 cps
Vibration Frequency Inner Ring Defect
0.1701 cps
Vibration frequency outer ring defect
0.1299 cps
Vibration Frequency Outer Ring Defect
0.1299 cps
Vibration frequency roller spin
0.0591 cps
Vibration Frequency Roller Spin
0.0591 cps
Volume
3.42
Volume unit
GLL
Volume Unit
GLL
Weight unit
LB
Width
8.00
2 15/16" Mounted Spherical Roller Bearing, Fixed Cast Iron 4-Bolt Square Flange Block with Pilot, Double Setscrew Locking Collar, Spring Loaded Heavy Contact Seal, One Open and One Closed Auxiliary Cap
How do I choose the right type of bearing for my application?
Start with the load and how it’s applied. You need to know if you’re dealing with radial loads, axial loads, or a mix of both. Then look at speed, operating environment, and space constraints. For example, ball bearings are great for high speed and lighter loads, while roller bearings handle heavier loads but usually at lower speeds. If there’s contamination, moisture, or heat involved, you may need sealed bearings or specific materials. In most cases, the right choice comes down to matching load type, speed, and environment to the bearing design.
What is a bearing and what does it do?
A bearing is a mechanical component that enables smooth rotational or linear motion by reducing friction between moving parts. Bearings support loads and facilitate the transfer of forces between moving elements, preventing direct metal-to-metal contact that would cause wear and heat buildup. Rolling element bearings contain balls or rollers that rotate within races (raceways) to minimize friction. Common types include ball bearings (used for moderate loads and high speeds), roller bearings (used for heavy loads at medium speeds), and angular contact bearings (designed for combined radial and axial loads). Bearings are essential in industrial equipment including motors, pumps, compressors, gearboxes, turbines, and conveyor systems.
What bearing materials are available and which should I use?
Standard bearing materials include: - Chrome Steel — Premium bearing steel used by SKF, NSK, Timken, and most manufacturers. Offers excellent hardness, fatigue resistance, and durability in standard industrial applications. Most common for ball and roller bearings. - Stainless Steel — Provides corrosion resistance for applications in wet, humid, or chemically corrosive environments. Used in food processing, marine, and pharmaceutical equipment. - Ceramic Hybrid Bearings — Combine steel races with ceramic rolling elements. Offer reduced friction, lower heat generation, and higher temperature capability. Used in high-speed, high-precision applications and aerospace. - Polymeric Bearings — Utilize fluoropolymer composites with embedded graphite or PTFE. Provide low friction in high-speed applications where lubrication film breakdown would be problematic. Material selection depends on operating environment (temperature, moisture, chemical exposure), speed, load, and precision requirements. Standard chrome steel bearings suit most industrial MRO applications.
What is bearing life (L10) and how does it affect my equipment maintenance?
L10 Life Definition (ISO 281) — L10 is the basic rating life at which 90% of a large group of identical bearings are statistically expected to survive under constant load and speed. It is calculated in millions of revolutions using the formula: L10 = (C/P)^p, where C is the basic dynamic load rating, P is the equivalent dynamic bearing load, and p is the life exponent (3 for ball bearings). Converting L10 to Operating Hours — To express L10 life in hours: L10h = (L10 × 10^6) / (60 × n), where n is rotational speed in RPM. For example, a bearing with L10 = 1,000 million revolutions operating at 3,600 RPM has approximately L10h ≈ 4,630 hours. Modified Life (L10a) — Actual bearing life also depends on lubrication quality, contamination, speed, temperature, and bearing accuracy. ISO 281 defines a modified life factor (a₁ × aISO) that adjusts the theoretical L10 for these real-world conditions. High-quality lubrication and proper maintenance can extend bearing life significantly; poor lubrication or high contamination reduces it. Why It Matters for Maintenance — L10 life helps you schedule preventive maintenance, budget for bearing replacement, and select bearings adequate for your duty cycle.
How do I choose the right bearing for my application?
Bearing selection depends on five key factors: 1. Load Type and Direction — Determine whether your application has radial loads (perpendicular to shaft), axial loads (along the shaft), or combined loads. Deep groove ball bearings suit primarily radial loads; tapered roller bearings excel at combined loads; thrust bearings handle pure axial forces. 2. Rotational Speed — Ball bearings support higher speeds with lower friction. Roller bearings are better for medium-speed, heavy-load applications. Verify bearing speed ratings against your operating RPM. 3. Load Capacity — Select a bearing with adequate load capacity for your application. Basic dynamic load rating (C) and basic static load rating (C₀) determine how much load the bearing can safely carry. 4. Lubrication Requirements — Choose between grease and oil lubrication based on speed, temperature, and load. High-speed or high-temperature applications typically require oil circulation; lower-speed applications can use grease. 5. Precision and Rigidity — Evaluate your application's tolerance for runout deviation. High-precision applications require tighter tolerances and higher-grade bearings.
What are dynamic and static load ratings, and why do they matter?
Static Load Rating (C₀) — The maximum load a stationary or slowly rotating bearing can support without permanent deformation of its rolling elements or raceways. Defined by ISO 76 as the load producing 0.01% permanent deformation of the rolling element diameter. Static load capacity is the limiting factor when a bearing operates at very low speeds or remains stationary under heavy loads. Dynamic Load Rating (C) — The constant load a bearing can endure for a specified number of revolutions (the L10 life, at which 90% of identical bearings are expected to survive). Dynamic load rating determines how long a bearing will last under rotating or oscillating motion. ISO 281 defines the L10 calculation using the formula: L10 = (C/P)^p, where C is dynamic load rating, P is equivalent dynamic load, and p is the life exponent (3 for ball bearings, 10/3 for roller bearings). Why They Matter — Static load rating determines if a bearing can handle peak loads without permanent damage (even if not rotating). Dynamic load rating determines operational life. For high-speed applications, dynamic rating is critical. For low-speed or stationary loads, static rating may be the limiting factor. Always verify both ratings against your application's load profile.
How should I maintain and lubricate bearings?
Lubrication Importance — Improper lubrication causes over 40% of bearing failures. Proper bearing lubrication prevents friction damage, dissipates heat, protects against corrosion, and acts as a barrier against contaminants (dust, moisture, debris). Lubrication Selection — Choose between grease and oil based on: - Grease: Suitable for low-to-medium speed, sealed bearings, and applications without continuous circulation. Easier to apply and retain. Common for motors, household appliances, and sealed units. - Oil Mist or Circulating Systems: Better for high-speed applications, high-temperature environments, and heavy-load machinery where heat dissipation is critical. Best Practices: 1. Map all lubrication points and create a maintenance schedule. 2. Use the correct lubricant type and viscosity grade specified by the bearing manufacturer. 3. Store lubricants in sealed, labeled containers away from moisture and contaminants. 4. Monitor bearing temperature and vibration; unusual heat or noise may indicate inadequate lubrication or bearing wear. 5. Replace bearings before reaching L10 life if contamination or lubrication failure is detected.
Slew ring bearings, also referred to as slewing bearings, slewing rings, or turntable bearings, are forms of bearings designed to allow rotational motion between several components.
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