HM88648-HM88611AS bearing: complete specifications & equivalents
The HM88648-HM88611AS is a ANSI ABMA 19.2 radial bearing sized 35.717 x 72.626 x 25.4 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 35.717 mm |
| Outer diameter D | 72.626 mm |
| Width B | 25.4 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 72 kN |
| Basic static load rating C0 | 84.5 kN |
| Limiting speed (mechanical) | 5400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 482 g |
| Manufacturer designation | NTN 4T-HM88648/HM88611AS |
| Standard | ANSI ABMA 19.2 |
| Catalog version | NTN 2203E 2026-09-25 |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN 2203E 2026-09-25) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN 2203E 2026-09-25); 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 & 4t-inch-series range
| Bore d | 1.406 in |
|---|---|
| Outer diameter D | 2.859 in |
| Width B | 1 in |
| ISO bore code | 48 |
| Radial section height (D−d)/2 | 18.5 mm |
| Smallest bore in 4t-inch-series | 12.7 mm |
| Largest outer diameter in 4t-inch-series | 260 mm |
| Width range across 4t-inch-series | 10.998–77.788 mm |
| Bore position in 4t-inch-series (smallest first) | 38 of 148 |
| Bore above smallest 4t-inch-series size | 23.017 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| HM88648-HM88610 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN cone 4T-HM88648 paired with a different cup (HM88610): cone interchangeable, cup differs — OD, assembled width T and ratings follow the cup. Verify the full cone/cup reference before substituting. |
| HM88648-610 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 35.717×72.626×25.4 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
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 HM88648-HM88611AS model number is decoded
For an inch shaft of 35.717 mm carrying combined radial and thrust load, NTN lists 4T-HM88648/HM88611AS, a single-row 4T tapered roller set of 72 kN C and 84.5 kN C0 inside the 72.626 mm OD cup. Reading the designation: 4T-HM88648/HM88611AS follows the ABMA inch convention — the number before the slash is the cone (inner ring with roller set and cage), the number after the slash is the cup (outer ring), and the heavy-medium HM family lettering ties the pair to its boundary plan. The 18.5 mm radial section over the 35.717 mm bore positions the contact line of the pair; abutment shoulders and spacers are dimensioned from that geometry, not from the bore alone. Cup-side note for HM88611AS: within the heavy-medium HM family tables the HM88648 cone is listed against several cup options, and it is the cup that fixes the 72.626 mm OD and the 25.4 mm assembled width — quote the full HM88648/HM88611AS pair, never the cone alone. NTN grades inch 4T bearings as open bearings without integral seals; at 35.717 mm bore the application supplies sealing and the grease fill or oil feed.
Typical equipment & failure modes
Common applications
- construction-equipment pivot and wheel positions
- mining and quarry conveyor drive pulleys
- machine-tool headstocks on inch spindles
- pump and blower drive shafts with combined load
Known failure patterns
- cone-rib and roller large-end smearing when the adjusted pair runs with preload but starved lubricant film
- cup creep and housing fretting when the cup seat is cut too loose for the rotating load
- flaking on one cone only when a bent shaft loads the O/X pair unevenly
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- brinell marks on cone and cup raceways from impact during handling or hammer fitting
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 35.717 mm class are adjusted in pairs; verify end play against the axle or gearbox drawing and re-torque after bedding-in instead of trusting the first setting on 4T-HM88648/HM88611AS.
- The heavy-medium HM family is proportioned for a high thrust share; swapping to a lighter LM or pure-numeric series at the same 35.717 mm bore cuts axial capacity even when the envelope fits — re-verify the load split before downgrading.
- Inch and metric bores collide on paper — 35.717 mm is 1.406 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- Open 4T-HM88648/HM88611AS sets have no seals: a hub or gearbox needs external sealing or the 5,400 r/min grease figure is meaningless once water reaches the cone rib.
- Fit selection follows the rotating ring: a rotating cone on a 35.717 mm shaft takes a k5/m5 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- The 72/84.5 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-HM88648/HM88611AS; internal geometry legitimately differs between inch-series makers, so re-verify ratings, adjustment and the exact cone/cup references before substituting another brand on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 4T-HM88648/HM88611AS?
4T-HM88648/HM88611AS is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 35.717 mm bore (1.406 in), 72.626 mm outside diameter and 25.4 mm assembled width T (2.859 × 1 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 72 kN, C0 84.5 kN, grease limiting speed 5,400 r/min, oil speed 7,200 r/min, mass about 482 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-HM88648/HM88611AS interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the HM88648 cone or the HM88611AS cup can be replaced by an identical reference from NTN or another ABMA-dimensioned maker. Pairing the cone with a different cup reference is a different catalogue row: OD, assembled T and the 72/84.5 kN ratings change with the cup.
What is the difference between 4T-HM88648/HM88611AS and a metric ISO 355 tapered bearing?
4T-HM88648/HM88611AS follows the ABMA inch boundary plan with cone/cup references; ISO 355 bearings use metric dimension-series numbers (302, 322, …). Even where a metric size looks close to 35.717×72.626×25.4 mm, the envelopes and contact angles differ — the two systems are not drop-in interchangeable; check every boundary value before substituting.
What does the 4T prefix on 4T-HM88648/HM88611AS mean?
4T is NTN's tapered roller bearing quality mark, stamped on cone and cup in the factory. It identifies NTN's 4T programme and is not a dimension or variant code, so interchange lists quote the bare HM88648/HM88611AS references; the 4T spelling is retained among this page's search aliases.
Why does 4T-HM88648/HM88611AS list two speeds, 5,400 and 7,200 r/min?
The lower figure, 5,400 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 4T-HM88648/HM88611AS at 7,200 r/min because oil removes rib-contact heat better. Real limits still depend on pair adjustment, oil flow and cooling.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN 2203E 2026-09-25 on 2026-10-01. Read our editorial & correction policy.