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Central Surplus Bearing Finder
A faster way to search our bearing inventory Today we’re launching the Central Surplus Bearing
Availability:
3 in stock
Tapered roller bearing single cone, 2.5000 in bore, 1.53125 in width, 78000 series. Rated 52,600 N dynamic radial. Mates with the 78549D double cup.
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| MFR / Brand | Timken |
|---|---|
| MPN | NA78250 |
| Model | NA 78250 |
| Bearing Type | Tapered Roller Bearing Cone, Open |
| ID | 2.5000 in (63.500 mm) |
| Width | 1.53125 in (38.894 mm) |
| Material | Case-carburized steel |
|---|---|
| Series | 78000 |
| Base Number | 78250 |
| Industry Terms | Tapered roller bearing cone; inner ring and roller assembly; taper cone; TRB cone |
| Common Misspellings | NA78520; N A78250; NA7825O; Timkin NA78250 |
| Overall Width | 1.53125 in (38.894 mm) |
| Mpn Variants | NA78250; NA-78250; NA 78250; 78250 NA |
| Manufacturer Status | Active Timken Catalog Item |
| Compatible With Replaces | Mates with Timken 78549D double cup |
| Arrangement Configuration | Single cone for two-row / TDO service |
| Precision Class | Not specified |
| Additional Attributes | Dynamic Radial Load Rating (C90): 52,600 N (11,800 lbf); Dynamic Axial Rating (Ca90): 77,900 N (17,500 lbf); e Factor: 0.87; K Factor: 0.67; Effective Center Location: 0.31 in (7.9 mm); Max Shaft Fillet Radius: 0.09 in (2.3 mm); Shaft Backing Shoulder Dia. Backface (db): 3.35 in (85 mm); Cage Location rel. to BF (Aa): 0.153125 in (3.8894 mm); Cage Location rel. to FF (Ab): -0.0765625 in (-1.9447 mm) |
| Dynamic Load Rating | 52,600 N (11,800 lbf) |
| Precision Rating | Not specified |
| Rolling Elements | Tapered Roller |
| Number Of Rows | 1 |
| Bore Type | Straight |
| Lubricant | Grease or oil |
| Harmonization Code | 8482.20.00 |
| Mounting Arrangement | Two-row / TDO service cone |
| Design Units | Imperial |
| Bearing Class | Not specified |
| Bearing Material | Case-carburized steel |
| Part Number | NA78250 |
| Cone Part Number | NA78250 |
| Cone Width | 1.53125 in (38.894 mm) |
| Cone Backface To Clear Radius | 0.09 in (2.3 mm) |
| Cone Frontface Backing Diameter | 3.27 in |
| Cross Reference 1 | SKF NA 78250 – same inch cone, NA two-row execution |
|---|---|
| Cross Reference 2 | FAG NA78250 – same inch cone, NA two-row execution |
| Cross Reference 3 | NTN NA78250 – same inch cone, NA two-row execution |
| Cross Reference 4 | Koyo NA78250 – same inch cone, NA two-row execution |
| Cross Reference 5 | NSK NA78250 – same inch cone, NA two-row execution |
| Cross Reference 6 | Bower / BCA NA78250 – same inch cone, NA two-row execution |
| Cross Reference 7 | Nachi NA78250 – same inch cone, NA two-row execution |
| Cross Reference 8 | PEER NA78250 – same inch cone, NA two-row execution |
| Cross Reference 9 | Timken 78250 – standard cone, no NA two-row grind |
Timken NA78250 inch tapered roller bearing cone. This is the cone, the inner ring complete with its tapered rollers and cage. Bore Diameter: 2.5000 in (63.500 mm). Inner Ring Width: 1.53125 in (38.894 mm). Series: 78000. Bore Type: Straight. Number Of Rows: 1. Rolling Elements: Tapered Roller. Closure Type: Open. Bearing Material: Case-carburized steel. Lubricant: Grease or oil. The matching double cup is the Timken 78549D.
NA — cone furnished for two-row and TDO service. The NA execution is ground to the width and effective-centre tolerance a two-row assembly needs, so two of them sit correctly either side of one double cup.
78250 — Timken inch cone number in the 78000 series, fixing the 2.5000 in bore, the raceway angle and the roller path.
Dynamic Radial Load Rating (C90, 90 million revolutions): 52,600 N (11,800 lbf). Dynamic Axial Rating (Ca90): 77,900 N (17,500 lbf). The axial figure exceeding the radial figure is what a shallow-angle inch cone does: it is built to carry thrust first.
e Factor: 0.87. K Factor: 0.67. Timken uses this pair to resolve a combined radial and thrust duty into an equivalent radial load. A K of 0.67 marks a steep contact geometry with a large thrust component per unit of radial load.
Case-carburized steel gives a hard raceway over a tough core, so the cone takes shock loading without through-cracking.
Shaft Backing Shoulder Diameter, Backface (db): 3.35 in (85 mm). Maximum Shaft Fillet Radius: 0.09 in (2.3 mm) — the largest fillet the shaft may carry and still be cleared by the cone corner. Effective Center Location: 0.31 in (7.9 mm). Cage Location relative to backface (Aa): 0.153125 in (3.8894 mm). Cage Location relative to frontface (Ab): -0.0765625 in (-1.9447 mm).
The cone presses onto the shaft with the large end of the raceway against the shoulder; the cup seats in the housing opposite it.
Unit Quantity: 1 Pc. One cone, comprising the inner ring, its rollers and the cage.
NA78250 is an industry inch cone number carried by SKF, FAG, NSK, NTN, Koyo, Bower/BCA, Nachi and PEER to the same envelope. Written variants in circulation include NA78250, NA-78250, NA 78250 and 78250 NA. The Timken 78250 without the NA prefix is the standard-execution cone, and the Timken 78549D is the double cup this cone pairs with.
Rockwell’s own product page for the Kinetix 6000 is down
A faster way to search our bearing inventory Today we’re launching the Central Surplus Bearing
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