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Timken 390A-3 tapered roller bearing cone, 2.5000 in / 63.500 mm bore, 0.8660 in wide, Class 3 precision. Cone only; mates Timken cups 394A, 394AS and 3920.
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| MFR / Brand | Timken |
|---|---|
| MPN | 390A-3 |
| Model | 390 A 3 |
| Bearing Type | Tapered Roller Bearing Cone |
| ID | 2.5000 in |
| Condition | New – Open box |
|---|---|
| Series | 395 |
| Base Number | 390A |
| Industry Terms | taper roller cone, inner cone, TRB cone, inner race and roller assembly, taper bearing inner |
| Common Misspellings | Timkin 390A-3, 390 A 3, 390a*3, taper roler cone 390A |
| Application Types | Gearboxes, axle and trailer hubs, agricultural and construction drives, general industrial shafting |
| Condition Note | Made In USA, New Old Stock, Class 3 Precision, cone assembly only — no cup, no carton |
| Bore Shaft Size | 2.5000 in / 63.500 mm |
| Mpn Variants | 390A-3, 390A 3, 390-A-3, 390A *3, 390A3, 390A |
| Manufacturer Status | Timken active industry number |
| Compatible With Replaces | Applications calling 390A cone with cup 394A, 394AS or 3920 |
| Precision Class | Timken Class 3 |
| Additional Attributes | Class 3 precision; cone assembly only, mating cup is a separate part number |
| Cage Material | Steel |
| Number Of Rows | 1 |
| Harmonization Code | 8482.20.00 |
| Design Units | Imperial (inch) |
| Bearing Class | Class 3 |
| Bearing Material | Case-Carburized Steel |
| Part Number | 390A-3 |
| Cone Part Number | 390A |
| Cone Width | 0.8660 in |
| Cone Backface To Clear Radius | 0.06 in |
| Cone Frontface Backing Diameter | 2.76 in |
| Cage Cone Frontface Clearance | 0.11 in |
| Cage Cone Backface Clearance | 0.05 in |
| Effective Center Location | -0.03 in |
| Cage Type | Stamped one-piece roller cage |
| Cross Reference 1 | 394A (mating cup) |
|---|---|
| Cross Reference 2 | 394AS (mating cup) |
| Cross Reference 3 | 3920 (mating cup) |
| Cross Reference 4 | 390A/394A (complete assembly) |
| Cross Reference 6 | Koyo 390A / NTN 390A / SKF 390A |
| Cross Reference 7 | Bower 390A / BCA 390A / Federal-Mogul 390A |
| Cross Reference 8 | Timken 390A (same cone, standard Class 4 / K precision) |
What this part is
A Timken 390A single tapered roller bearing cone in Class 3 precision: the inner ring with its full tapered roller set and cage, one half of a tapered roller bearing. The cup (outer race) is a separate Timken part number and is not included. The 390A cone is one of the most widely used inch cones in the 2-1/2 in bore range, appearing in gearboxes, trailer and axle hubs, agricultural drives and general industrial shafting.
Designation breakdown
390: Timken imperial TS cone sequence. A: design revision within the sequence; 390 and 390A are different bores. -3: Timken precision Class 3, a tighter bore, width and runout grade than the standard Class 4 / K tolerance. Cartons stamp it with a leading asterisk, so the part also reads 390A *3 and 390A3.
Specifications
Manufacturer: The Timken Company. Part Number: 390A-3. Base Number: 390A. Cone Part Number: 390A. Bearing Type: tapered roller bearing cone, single row, TS series. Series: Timken imperial TS tapered single, 390 sequence. Bore (d): 2.5000 in / 63.500 mm. Cone Width (B): 0.8660 in. Bore Type: straight. Number of Rows: 1. Precision Class: Timken Class 3. Bearing Class: Class 3. Cage Type: stamped one-piece roller cage. Cage Material: steel. Bearing Material: case-carburized steel. Closure Type: open. Cone Backface To Clear Radius: 0.06 in. Cone Frontface Backing Diameter: 2.76 in. Cage-Cone Frontface Clearance: 0.11 in. Cage-Cone Backface Clearance: 0.05 in. Effective Center Location: -0.03 in. Design Units: imperial (inch). Harmonization Code: 8482.20.00. Mating Cups: 394A, 394AS, 3920.
What these specifications mean in practice
The 390A is a relatively narrow cone for its bore: moderate thrust capacity, good radial capacity, compact axially. Tapered rollers carry combined radial and one-way thrust because the roller and raceway apexes meet at a common point, so they are fitted in opposed pairs and the pair’s axial setting is established at build. Class 3 tightens bore, width and runout, which makes a dialled-in endplay repeatable and keeps a gear contact pattern stable.
Set composition
Cone assembly only: inner ring, tapered rollers and cage as one non-separable unit. No cup is included; the mating cup is a separate part number.
Interchange
Standard assemblies are 390A/394A and 390A/3920. Inch tapered roller numbering is an industry standard rather than a brand code, so Koyo 390A, NTN 390A, SKF 390A, Bower/BCA 390A and Federal-Mogul 390A describe the same cone. A plain 390A without the -3 suffix is the same cone in standard Class 4 / K precision.
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