3780 Bearing Dimensions
3780 inch tapered roller bearing cone, paired with the 3720 cup: 50.8 mm (2.000 in) bore, 93.264 mm OD, 30.162 mm width (FULI catalog). Quote.
3780 specifications
| Cone bore d | 50.8 mm (2.000 in) |
|---|---|
| Cone width B | 30.302 mm |
| Matching cup | 3720 |
| Cup outside diameter D | 93.264 mm (3.672 in) |
| Total width T | 30.162 mm (1.187 in) — assembled width of cup and cone |
| Seal / shield options | Open (cup and cone, no seals) |
| Material | GCr15 chrome bearing steel (rings and rolling elements) |
| Radial clearance | Set during mounting (adjustable, not a C-class value) |
| Load ratings | See the cone and cup pairs table below |
3780 cone and cup pairs
| Cone | Cup | Bore d | OD D | Width T | Cr (kN) | C0r (kN) |
|---|---|---|---|---|---|---|
| 3780 | 3720 | 50.8 mm (2.000 in) | 93.264 mm (3.672 in) | 30.162 mm (1.187 in) | 113 | 153 |
Dimensions from FULI's catalog. A cone (inner ring with rollers and cage) and a cup (outer ring) make up one bearing; the pairs above are the matching numbers listed in FULI's catalog. Values from FULI's catalog; confirm for your application.
How to read the 3780 designation
| Segment | Meaning |
|---|---|
| 3780 | Designation breakdown not available for this model. |
3780 interchange
3780 is an inch tapered roller bearing cone. Inch tapered roller bearings are ordered by cone number and cup number. Most makers use the same cone and cup numbers for the same size, but always check the cup number as well. Send us the numbers on your old bearing and we confirm the match before quoting.
Brand names are trademarks of their respective owners. FULI is not affiliated with, authorized by or endorsed by these companies. Part numbers are shown for interchange reference only. FULI dimensions, load ratings and speeds come from the FULI catalog.
3780 compared with nearby cone sizes
The 3780 cone has a 50.8 mm (2.000 in) bore and a cone width of 30.302 mm. FULI's catalog pairs it with cup 3720 (93.264 mm outside diameter, 30.162 mm total width).
The next smaller cone on this site is 368A, with a 50.8 mm bore (0 mm smaller) and cup 362A.
The next larger is 3784, with a 50.8 mm bore (0 mm larger) and cup 3720.
Cup 3720 is also listed with 3784, so the same housing bore can take a different cone if the shaft size changes.
The metric tapered bearing on this site closest in bore is 32010 (50 × 80 × 20 mm). Its sizes differ from the 3780 pair, so the two are not interchangeable; it is given only as a size reference.
| Cone | Cup | d × D × T | Cr (kN) |
|---|---|---|---|
| 28580 | 28521 | 50.8 × 92.075 × 24.6 mm | 86.3 |
| 368 | 362A | 50.8 × 88.9 × 20.638 mm | 75.8 |
| 368A | 362A | 50.8 × 88.9 × 20.638 mm | 75.8 |
| 3780 | 3720 | 50.8 × 93.264 × 30.162 mm | 113 |
| 3784 | 3720 | 50.8 × 93.264 × 30.162 mm | 113 |
| 385A | 382A | 50.8 × 96.838 × 21 mm | 81.6 |
| LM104949 | LM104911 | 50.8 × 82.55 × 21.59 mm | 70.5 |
Sizes and Cr from FULI's catalog; — = not listed on this site.
3780 load ratings
3780/3720 has a dynamic load rating Cr of 113 kN and a static rating C0r of 153 kN in FULI's catalog. The ratings belong to the cone and cup as a pair; a different cup changes them.
Speed limits and weights for inch cones are not listed in the catalog; ask us and we send them with the quotation.
Values from FULI's catalog; confirm for your application.
3780 size in inches and millimetres
3780 is made to inch sizes. The 50.8 mm bore is 2 in. The millimetre values in the catalog are conversions of the inch sizes.
| Dimension | Millimetres | Inches |
|---|---|---|
| Cone bore d | 50.8 mm | 2.0000 in |
| Cup outside diameter D (3720) | 93.264 mm | 3.6718 in |
| Total width T | 30.162 mm | 1.1875 in |
| Cone width B | 30.302 mm | 1.1930 in |
| Cup width C | 23.812 mm | 0.9375 in |
Converted at 1 in = 25.4 mm and rounded to four decimals.
Mounting 3780 (general guidance)
General guidance, not a FULI specification: on a turning shaft the cone is a tight fit on the shaft and the cup a lighter fit in the housing, so the cup can be moved when the bearing pair is adjusted. Inch bearing fits are given as shaft and housing limits in inches in the bearing makers' tables; follow the drawing of your machine.
Tapered roller bearings carry radial load and axial load in one direction, so 3780 is normally used as one of a pair, and the end play or preload is set at mounting.
If the outer ring turns and the shaft stands still, as in an idler pulley or a wheel hub, the fits are reversed: the housing gets the interference fit (for example N7 or P7) and the shaft a sliding one (g6 or h6).
Grease for 3780
FULI supplies tapered roller bearings rust-protected and normally without grease; grease is packed in when the bearing is mounted. Relubricating 3780/3720 from the side takes about 14.1 g each time by the formula in our grease calculator: 0.005 × D × T = 0.005 × 93.26 × 30.16.
How FULI supplies 3780
3780 is supplied as a cone, as a cup or as a complete cone and cup pair, as your order states. Where an order states a requirement for the total width T (30.162 mm for 3780/3720), each set is checked on a height gauge before packing.
Rings are marked with a brand you are authorised to use, with the FULI brand, or left neutral, as your order states. The box is printed with the model, precision class and brand.
Inquiries that give only one number are the usual cause of a wrong quote, so write both the cone and the cup number, for example 3780/3720.
Tools and guides for 3780
Typical applications
- Vehicle wheel hubs and axles
- Gearboxes and reducers
- Agricultural machinery
- Conveyor pulleys
FAQ
What size is 3780 in mm?
The 3780 cone has a 50.8 mm bore (2.000 in). With cup 3720 the bearing is 50.8 × 93.264 × 30.162 mm (d × D × T).
What is the difference between 3780 and 3784?
3784 has a 50.8 mm bore against 50.8 mm for 3780, and pairs with cup 3720 (50.8 × 93.264 × 30.162 mm) instead of 3720 (50.8 × 93.264 × 30.162 mm). The two are not interchangeable; order by the numbers on the old cone and cup.
How much grease does 3780/3720 need?
About 14.1 g each time it is relubricated from the side (0.005 × 93.26 × 30.16). FULI ships it rust-protected without grease, so the first fill is made at mounting.
Which cup goes with the 3780 cone?
FULI's catalog pairs the 3780 cone with cup 3720. Tell us whether you need the cone, the cup or both when you send the inquiry.
Is 3780 the same size across brands?
3780 is an inch tapered roller bearing cone number. Most makers use the same cone and cup numbers for the same size, but check the cup number too. Send us the numbers on your old bearing and we confirm the match.