NAF200 Series 4-Bolt Flange Bearing Units — Standard Duty, Eccentric Locking Collar
The NAF200 series combines the square four-bolt flange housing of the UCF200 with the eccentric locking collar insert of the NAP200 pillow block. The eccentric collar engages the shaft by rotating in the direction of shaft rotation — as the shaft turns, the collar tightens against the inner ring, making retention more secure under sustained unidirectional drive than a static setscrew. This self-reinforcing grip under rotation makes the NAF200 the standard choice for flange-mounted bearings on drives where the shaft runs in one direction and removal of the bearing for maintenance must be quick and clean.
Eccentric Collar Locking — Mechanism and Application Logic
The NAF200 insert carries an eccentric locking collar on the non-drive side of the inner ring. The collar's bore is offset from its outer diameter by a small eccentricity. When the collar is rotated in the direction of shaft rotation and locked with the set pin, the eccentric geometry creates a wedging force that increases with load, making the NAF200 progressively more secure under operation — unlike a setscrew whose retention is fixed by the torque applied at installation.
The trade-off is directionality: the eccentric collar releases if the shaft rotates in the opposite direction to the collar's lock direction. NAF200 is therefore not suited to reversing drives, jogging, or oscillating shafts. For bidirectional drives in a four-bolt flange housing, the {link('/product/uef200-series-4-bolt-flange-bearing-units/','UEF200 concentric collar series')} or the {link('/product/ucf200-series-4-bolt-flange-bearing-units/','UCF200 setscrew series')} are the appropriate choices.
Key Features
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Eccentric Collar Self-Tightening
Collar tightens under shaft rotation — grip increases with operating load. More secure than setscrew under sustained unidirectional drive and vibration.
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Square Four-Bolt Flange Plate
Four-corner bolt pattern resists housing tilt under eccentric radial load from belt tension or chain pull. Hollow base standard; solid base (SB) available.
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Wide Inner Ring UC Insert
Self-aligning spherical OD accommodates 2° misalignment. Same housing footprint as UCF200 — direct swap to eccentric locking without re-drilling.
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NAF201S–203S Compact Variant
Slim S-series for 12–17 mm bore where the F dimension is omitted — lighter and narrower for compact machine frames.
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Standard Grease Access
Grease fitting at 45° standard. Re-lubrication accessible without housing removal in standard mounting orientations.
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GB / ISO / ANSI / JIS Compliant
Drop-in replacement for NAF200-pattern eccentric collar flange units. Housing J, A, bolt-circle identical to UCF200 for same bore.
Full Dimensional Specifications
| Unit No. | d mm | d inch | L mm | J mm | A2 mm | A1 mm | A mm | N mm | S mm | Z mm | F mm | Bolt | kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NAF201S~203S / 201-8S~203-11S | 12~17 | 1/2~11/16 | 76 | 54 | 15 | 11 | 25.5 | 12 | 13.9 | 38.4 | — | M10 | 0.5 |
| NAF201 / 201-8 | 12 | 1/2 | 86 | 64 | 15 | 12 | 25.5 | 12 | 17.1 | 41.6 | 32 | M10 | 0.66 |
| NAF202 / 202-10 | 15 | 5/8 | 86 | 64 | 15 | 12 | 25.5 | 12 | 17.1 | 41.6 | 32 | M10 | 0.66 |
| NAF203 / 203-11 | 17 | 11/16 | 86 | 64 | 15 | 12 | 25.5 | 12 | 17.1 | 41.6 | 32 | M10 | 0.66 |
| NAF204 / 204-12 | 20 | 3/4 | 86 | 64 | 15 | 12 | 25.5 | 12 | 17.1 | 41.6 | 32 | M10 | 0.66 |
| NAF205 / 205-14~16 | 25 | 7/8~1 | 95 | 70 | 16 | 14 | 27 | 12 | 17.5 | 42.9 | 36 | M10 | 0.80 |
| NAF206 / 206-18~20 | 30 | 1-1/8~1-1/4 | 108 | 83 | 18 | 14 | 31 | 12 | 18.3 | 48.1 | 42 | M10 | 1.20 |
| NAF207 / 207-20~23 | 35 | 1-1/4~1-7/16 | 117 | 92 | 19 | 16 | 34 | 14 | 18.8 | 51.3 | 49 | M12 | 1.60 |
| NAF208 / 208-24/25 | 40 | 1-1/2~1-9/16 | 130 | 102 | 21 | 16 | 36 | 16 | 21.4 | 55.9 | 55 | M14 | 1.90 |
| NAF209 / 209-26~28 | 45 | 1-5/8~1-3/4 | 137 | 105 | 22 | 18 | 38 | 16 | 21.4 | 56.9 | — | M14 | 2.30 |
| NAF210 / 210-30/31 | 50 | 1-7/8~1-15/16 | 143 | 111 | 22 | 18 | 40 | 16 | 24.6 | 60.1 | 64 | M14 | 2.60 |
| NAF211 / 211-32~35 | 55 | 2~2-3/16 | 162 | 130 | 25 | 20 | 43 | 19 | 27.8 | 68.6 | 71 | M16 | 3.80 |
| NAF212 / 212-36~39 | 60 | 2-1/4~2-7/16 | 175 | 143 | 29 | 20 | 48 | 19 | 31 | 75.8 | 78 | M16 | 4.80 |
| NAF213 / 213-40 | 65 | 2-1/2 | 187 | 149 | 30 | 22 | 50 | 19 | 34.3 | 81.4 | 85 | M16 | 6.00 |
| NAF214 / 214-44 | 70 | 2-3/4 | 193 | 152 | 31 | 22 | 54 | 19 | 34.3 | 82.4 | 91 | M16 | 6.30 |
| NAF215 / 215-47/48 | 75 | 2-15/16~3 | 200 | 159 | 34 | 22 | 56 | 19 | 37.3 | 88.8 | 96 | M16 | 7.20 |
→ Scroll horizontally to view all columns. Catalogue dimensions for reference only — engineering drawings required before order.
S-suffix (NAF201S–203S) = slim variant without F dimension. F = eccentric collar locking pin hole diameter. Solid base: suffix SB. Collar lock direction must match shaft rotation direction — specify at order if non-standard.
Applications
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Unidirectional Belt & Chain Conveyors
Drive sprocket and pulley shafts on single-direction conveyors where the eccentric collar tightens progressively under sustained belt tension, providing more reliable long-term retention than setscrew in high-vibration environments.
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Agricultural Harvester Frame Drives
Threshing cylinder and straw walker frame-mount drive shafts where the drive direction is fixed and the flange mounting simplifies bearing installation on vertical implement frame panels.
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Fan & Blower Unidirectional Shafts
Centrifugal fan shaft supports on panel-mounted blower units where the fan runs in one direction continuously and the eccentric collar provides better retention than setscrew under persistent vibration.
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Packaging Machine Main Drives
Main drive shaft supports on vertical-frame packaging machinery where single-direction operation and easy bearing replacement without shaft damage are both priorities.
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Aggregate & Mining Auxiliary Drives
Feeder and transfer conveyor drive shafts on vertical side-frame structures where the eccentric collar's self-tightening action compensates for frame vibration that would loosen a conventional setscrew.
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Upgrade from UCF200 on Unidirectional Drives
Drop-in upgrade from UCF200 setscrew where field experience shows setscrew loosening under vibration. Housing dimensions are identical — replace only the insert bearing and collar.
📦 MOQ & Order Information
- Standard parts: quantity-based MOQ applies per model number.
- High-value / large items: minimum order by USD order value.
- New-client samples: 1–5 pcs available at sample price for first-time buyers.
- Multi-model combines: aggregate orders of USD 1,500 or more across models accepted.
- Special materials / processes: subject to process MOQ — confirm at inquiry stage.
- Retail (1–2 pcs): not accepted. Minimum sample order is 1–5 pcs at sample pricing.
Engineering drawings must be submitted and approved before order confirmation. Catalogue dimensions are for reference only.
Frequently Asked Questions
Can NAF200 be used on a reversing drive?
No — eccentric collar releases under reversal. Use UCF200 (setscrew) or UEF200 (concentric collar) for bidirectional drives.
What is the F dimension?
Diameter of the locking pin hole in the eccentric collar. S-suffix variants omit F.
Is the housing interchangeable with UCF200?
Yes — J, A, bolt-circle identical. Replace insert only to switch locking style.
What is the MOQ?
Standard parts: quantity-based MOQ. Samples 1–5 pcs. Multi-model from USD 1,500. Retail 1–2 pcs not accepted.
Request a Quote for NAF200 Series
Provide shaft diameter, shaft rotation direction, bore type, and quantity. Contact us.
