MP-308

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MP-308

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Sealmaster MP-308 Gold Line Mounted Cast Iron Two Bolt Pillow Block Ball Bearing, 52100 Bearing Steel, Black Oxided w/Setscrew Lock, Item# 710220. Non-Expansion (Fixed), 40mm Straight Bore, ±2.0° Static Only Misalignment, Lithium Complex NLGI 2 Grease, Relubricatable. Felt Labyrinth Seal. Zone-Hardened Inner Race, Standard Clearance, Replaceable Insert. A Regal-Rexnord Brand Product.

$651.66

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Item: MP-308 | Model #: 710220

Overview
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MP-308

Base Model Number	MP
Base to Center Height	2.938"
Base Width	2.625"
Bearing Housing	Gray Pillow Block-High Base, One Piece
Bearing Insert Coating	Black Oxide Coated
BOLT	0.625"
Bolt Center Max	6.750"
Bolt Center Min	5.500"
Bolt Center to Center Length	5.5000" to 6.7500"
Bore Size	40mm (Straight Bore)
Category Name	Mounted Bearings
Centerline to Front Face	1.188"
FOOT HEIGHT	0.813"
Housing Base	Solid
Housing Material	Cast Iron
Includes	No End Cap
Inner Race Length	1.938"
Insert Material	52100 Bearing Steel, Black Oxided
Insert No.	5308

Locking Type	Setscrew
Lubrication	Lithium Complex NLGI 2 Grease, Relubricatable
Misalignment	±2.0° (Static Only)
Model Number	710220
Model Series	Gold Line Mounted Ball Bearing
Overall Height	4.563"
OVR LENGTH	8.750"
Parts Series	Medium Duty
Product Notes	Zone-Hardened Inner Race, Standard Clearance, Replaceable Insert
Quick Specs	Mounted Cast Iron Two Bolt Pillow Block Ball Bearing - 52100 Bearing Steel, Black Oxided - Setscrew Lock
Radial Dynamic Load Capacity	7901 lbs
RETAINER	Brass Land Riding Retainer
Rolling Element	Ball Bearing
Seal Type	Felt Labyrinth
Speed (RPM)	3800 RPM Maximum
Type	Non-Expansion (Fixed)
UPC	662461053973

Gold Line Mounted Ball Bearings Information

Product Type

Bearings

Features & Benefits

FEATURES AND BENEFITS

WIDE OUTER RING
Sealmaster® has the industry’s widest outer ring. The black oxided outer ring is 20 to 30% wider than industry standard outer rings. This feature results in increased grease capacity, and room for improved sealing options. A wider outer ring has increased surface area contact with the housing to better absorb shock load.

LOCK PIN AND DIMPLE
The Sealmaster exclusive locking pin and dimple system provides a direct lubricant path into the bearing cavity & ball path instead of around a lubrication groove. The pin also prevents outer ring rotation (sometimes referred to as “creep”), and allows ±2° static misalignment of the bearing insert.

MULTIPLE SEALING OPTIONS

FELT SEAL WITH FLINGER
The standard felt seal provides a tight labyrinth seal which retains lubrication and acts as a filter to exclude contamination. The external stamping is a flinger which shields the felt from large contaminants and directs them away from the sealing surface. The design operates with less drag and less heat generation than rubber contact seals.

SINGLE LIP CONTACT SEAL
Single Lip Contact Seal consists of a nitrile rubber washer in metal shroud to shield the lip from large contaminants. The seal is designed to balance drag and protection in wet and dry environments. This can be specified by adding the suffix C to the part number.

MULTIPLE LOCKING METHODS

SETSCREW LOCKING
120° spaced, balanced three point contact minimizes inner ring distortion vibration, reduces noise, and improves reliability. Precision manufactured diamond faceted setscrews contribute to improved clamping and resistance to back out.

SKWEZLOC® CONCENTRIC LOCKING COLLAR
SKWEZLOC is a concentric locking collar clamp design that results in near perfect concentricity of the shaft to the bearing bore and maintains near perfect ball path roundness, while reducing fretting corrosion. This design eliminates the shaft damage of setscrew locking, and minimizes bearing induced vibration for smoother, quieter operation. The collar has a TORX® Plus head cap screw that outlasts stripping 12 times longer than hex head cap screws. The Skwezloc locking collar has been redesigned to accommodate “Commercial” grade Turned and Polished (T&P) shaft tolerances with improved lock reliability on Turned, Ground and Polished (TG&P) shaft tolerances. The new design has been a rolling implementation beginning in 2017 continuing through 2018.

ZONE HARDENED INNER RACE
Sealmaster® incorporates a unique heat treat process that hardens the inner race only where it is needed…under the ball path. The black oxided zone hardened inner race results in improved lock reliability as a result of less distortion at the setscrew location and improved thread conformity resulting in improved clamping and resistance to setscrew back-out

LAND RIDING RETAINER
The Sealmaster unique land riding metal retainer design provides superior pocket clearance that allows for 360° grease circulation around the rolling elements resulting in better retained and utilized lubrication. The land riding design of the retainer minimizes wear on both Ball and retainer, while maximizing stability, which is especially important in applications involving vibration, shock loading or high operating speeds.

SOLID BASE
Solid bases are standard on Sealmaster Gold ball bearing pillow blocks. The solid base provides improved stability, resistance to shock and vibration and prevents frame buckling under base compared to semi-solid and hollow mounting bases.

HOUSING FIT
All bearings are assembled with a controlled housing fit between the bearing outer ring and housing bore. This fit allows the bearing to properly self-align in common industrial applications. Special fits are available based on your specific application need.

NAMEPLATE
Metal nameplate riveted to the housing allows for easy identification even after years of operation.

TIME SAVING™ AXIAL GROOVE
Patented design that provides clearance from the burr created by the setscrew used to lock the bearing to the shaft. This feature has no impact to ball path roundness, load and speed rating, strength or bearing performance. This feature is available in both a medium 2 7/16" and up, and standard 2 11/16" and up shaft sizes.

Options

SEALMASTER® GOLD MOUNTED BALL BEARING OPTIONS
Bearings are typically selected using L10 fatigue life calculations based on ideal operating conditions. However, most bearing problems are not fatigue related, but occur due to contamination, lubrication starvation, or other environmental issues. As a result, our engineers have developed custom solutions to meet the varying severity, operating parameters and maintenance regularity, such as Reduced Maintenance and Custom Select.

REDUCED MAINTENANCE “RM”
Sealmaster Reduced Maintenance bearings are the result of a patented Tapered Lands bearing race profile which means that critical lubricant is circulated more efficiently, while requiring no regular service intervals. The bearing are supplied from the factory with a plug instead of a lubrication fitting.

The outer land surface in a conventional bearing is parallel to the axis of the inner ring. The Tapered Lands surface is tapered in a radial direction toward the bearing race. This subtle yet crucial design change allows lubricant to more easily flow back to the raceway. With improved bearing lubricant circulation comes significantly longer bearing service life. This improved circulation and service life comes without any reductions in bearing radial or thrust capacities.

* For bearings that are maintained and relubricated on a regular basis, there is no significant difference in expected service life.

HIGH TEMPERATURE "HT"
High temperature bearing with increased radial internal clearance to accommodate thermal expansion of components and Nomex* seal and high temperature synthetic grease.

HIGH PERFORMANCE HIGH TEMPERATURE "HI"
High temperature bearing with increased radial internal clearance to accommodate thermal expansion of components and Nomex** seal and Krytox* 226 grease. Available in expansion version in some sizes with half-dog and wire, suffix “HIY”

HIGH TEMPERATURE AIR HANDLING “HTA”
Utilizes the same features as our high temperature “HT” option with the additional features that are important in Air Handling equipment:
• Controlled air handling housing fit that allows the bearing to properly self align when mounted on lightweight frames
•Two stage noise testing verification procedure for quiet operation
• For standard operating temperatures, consider the Air Handling “CXU” option shown below

HIGH TEMPERATURE CONTACT SEAL “HTC”
High temperature bearing with increased radial internal clearance to accommodate thermal expansion of components, single lip silicone fiberglass or FKM spring seal and high temperature synthetic grease.

HIGH CONTAMINATION “DRT”
Heavy Duty Multi-Lip contact seal (depending on size and series, either supplied with “2C” double lip or “3C” triple lip seal), 100% Grease Fill with Sealmaster GoldPlex HP Grease.

HIGH SPEED “HS”
• Available in SKWEZLOC locking collar only
• Backed off, felt seal reduces contact area between the felt sealing material and the internal metal flinger
• Controlled air handling housing fit that allows the bearing to properly self-align when mounted on lightweight frames
• Increased radial internal clearance to accommodate radial thermal expansion of components

AIR HANDLING “CXU”
Utilizes many of the same features as standard Sealmaster Gold Mounted Ball Bearings but designed and manufactured for Air Handling equipment.
• Controlled air handling housing fit that allows the bearing to properly self-align when mounted on lightweight frames
• Available with the standard Sealmaster felt seal for decreased energy consumption
• Two stage noise testing verification procedure for quiet operation

HIGH TEMPERATURE AIR HANDLING “HTA”

LOW DRAG “LO”
• Felt seal cut down to reduce drag
• Provides excellent barrier that works to retain grease and acts as a filter to reduce the ingress of debris contaminants
• Features a channeling grease that reduces drag while lubricating the bearing
• A reduced housing fit to allow for the bearing to properly self-align on light weight frames

X-TRA LOW DRAG “XLO”
• Felt seal cut down and oil soaked for extra low drag
• Oil lubricated and supplied with an adapter and plug for easy field relubrication
• A reduced housing fit to allow for the bearing to properly self-align on light weight frames

CSK - 90° Grease Fitting
CSJ - 45° Grease Fitting
CTJ - Adapter and Plug
CTY - Plug
W - Adapter and Grease Fitting

NOTE:
• Fittings are designed to properly position the lock pin anti-rotation device. Other fittings not designed for Sealmaster® brand bearings may not provide this function causing reduced bearing life.
• Fittings are factory adjusted to properly position the lock pin anti-rotation device. Improper field adjustment of the fitting may cause reduced bearing life.

EXPANSION UNITS OPTIONS
Axial shaft expansion is compensated by a non-expansion (fixed) and expansion (float) arrangement. Many bearings are offered in both fixed and float arrangements and have identical mounting dimensions. It is recommended to use both units on one shaft in high temperature applications to help account for linear shaft expansion.

GREASES
Optional greases are readily available, consult Application Engineering for complete list

HIGH TEMPERATURE SYNTHETIC
• Used in HT, HTA, and HTC suffix modified bearings
• High quality, synthetic hydrocarbon, lithium complex thickened grease NLGI#2, and ISO 220 viscosity
• Superior high temperature (200 F to 400 F) stability

KRYTOX* EXTENDED LUBE
• Used in HI suffix modified bearings
• KYRTOX® GPL 226, an extremely high performance perfluorinated oil and PTFE thickened grease
• KRYTOX grease has a superior service life and therefore diminishes re-lubrication frequency and extends life
• Engineers have found that, compared to other high temperature greases, the thermal stability and lubricity of the KRYTOX can improve high temperature bearing life by a factor of 4 to 45 times