7944 bearing: complete specifications & equivalents
The 7944 is a ISO 15 radial bearing sized 220 x 300 x 38 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 220 mm |
| Outer diameter D | 300 mm |
| Width B | 38 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 207 kN |
| Basic static load rating C0 | 239 kN |
| Fatigue load limit Pu | 9.85 kN |
| Limiting speed (mechanical) | 2000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 7740 g |
| Manufacturer designation | NTN 7944 |
| Standard | ISO 15 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & 7900-series range
| Bore d | 8.661 in |
|---|---|
| Outer diameter D | 11.811 in |
| Width B | 1.496 in |
| ISO bore code | 44 |
| Radial section height (D−d)/2 | 40 mm |
| Smallest bore in 7900-series | 25 mm |
| Largest outer diameter in 7900-series | 420 mm |
| Width range across 7900-series | 9–56 mm |
| Bore position in 7900-series (smallest first) | 28 of 32 |
| Bore above smallest 7900-series size | 195 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7944 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the supplier. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 7944 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, 7944 appears as a extra-light, high-speed 7900 single-row family bearing of 220 mm bore, 300 mm outside diameter and 38 mm width. Decoding 7944: 79 is the single-row dimension series (extra-light, high-speed 7900 single-row family), with 44 encodes the 220 mm bore (bore code x 5); with no letter after the digits it is the standard 30 deg contact-angle execution — the 40 deg version carries a B. NTN prints 207 kN dynamic and 239 kN static for this size and a 9.85 kN fatigue load limit Pu. Selection starts from the thrust share: as axial load grows past roughly half the radial load, an angular-contact position of this section usually outlives a deep-groove one. A 220 mm shaft typically takes a m6/n6 fit for rotating inner-ring load; keep the housing bore to G6/H6 class so the contact geometry is not distorted.
Typical equipment & failure modes
Common applications
- large pump and turbine auxiliary shafts
- steel-plant conveyor and table roll drives
- wind-turbine and heavy-machinery auxiliaries
- heavy industrial gearbox main shafts
Known failure patterns
- impact brinelling dents on the 30 deg contact path after a shaft-side hammer blow during mounting, because axial shock travels straight through the contact angle
- loss of preload after housing-fret or shaft creep, leaving the pair loose — ball skidding, cage rattle and a falling natural frequency follow
- machined-cage land scoring when a high-speed spindle runs past its grease rating and the cage runs dry on its guidance surface
- contamination-induced denting — hard particles rolled into the contact ellipse become the initiation points for surface fatigue
- current-erosion pitting on VFD-driven motor shafts, first visible as a grey frosted band across both raceways
Selection pitfalls — read before you substitute
- At this size the shaft fit, shoulder geometry and preload procedure dominate the outcome; a 220 mm bore bearing forgives nothing in a poorly machined housing.
- The 7900 extra-light section is chosen for speed and stiffness, not for load margin — check that C0 239 kN really covers the worst static case before substituting it for a 7000.
- A 7944 mounted the wrong way round still turns smoothly by hand; the failure shows up weeks later as raceway flaking on the unloaded-looking side.
- If the application vibrates at standstill (transport, idle machine next to a running line), specify protection: the contact ellipse of a preloaded bearing false-brinells faster than a loose one.
- Never use a four-point or double-row bearing as a like-for-like swap for a single 7944 without re-checking axial float, heat and housing width — the kinematics differ.
- The 207/239 kN ratings and 9.85 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7944; internal geometry legitimately differs between manufacturers, so re-verify ratings, contact angle and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 7944?
7944 is a single-row angular contact ball bearing to ISO 15: 220 mm bore, 300 mm outside diameter, 38 mm width (8.661 x 11.811 x 1.496 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 207 kN, C0 239 kN and a 9.85 kN fatigue load limit Pu; the grease limiting speed is 2,000 r/min and the oil rating 2,700 r/min; mass about 7740 g.
How is the 7944 designation structured?
79 is the single-row dimension series (extra-light, high-speed 7900 single-row family); 44 encodes the 220 mm bore (bore code x 5); with no letter after the digits it is the standard 30 deg contact-angle execution — the 40 deg version carries a B. The 300 mm OD and 38 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7944 support?
One 7944 alone takes thrust in one direction only, along its 30 deg contact angle; reversing thrust calls for a second bearing or a factory-matched DB/DF/DT pair (the catalogue right-hand columns list the paired ratings). Radial load is always carried as a combined load through the angled contact.
What lubrication speeds does NTN print for 7944?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 2,000 r/min and the oil rating 2,700 r/min. These are catalogue ceilings for a correctly mounted bearing with the stated lubricant; preload, fill quantity, ambient heat and paired arrangements all move the real limit.
What should be checked before substituting another make for 7944?
The 220/300/38 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 207 kN / C0 239 kN, the speed figures, contact angle and suffix meaning against the donor catalogue before swapping on a rated drive.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.