Product Deep-Dive
Taper Bore Adapters Explained: How to Convert Straight-Bore Components to Taper Lock
Product Deep-Dive
A taper bore adapter is useful when a component has a straight bore but the machine standard calls for a removable taper-bushing shaft connection. The adapter creates the tapered interface that the component does not have on its own, allowing the selected bushing to be used without replacing the entire driven component.
The conversion is only safe when the component has enough material and the adapter dimensions are matched correctly. An adapter cannot compensate for a thin, cracked or poorly aligned hub, and it should not be selected from shaft diameter alone.
How the adapter changes the interface
The adapter sits between the straight-bore component and the taper bushing. Its geometry must match the selected bushing series on one side and the component bore on the other. The table links each EP adapter to the bushing number it is designed around.
EP-1215B to EP-4545B reference
| EP adapter | Matched EP bushing | A (in) | B (in) | C (in) | Approx. weight (lb) |
|---|---|---|---|---|---|
| EP-1215B | EP-1215 | 1 7/8 | 1 1/2 | 2 3/8 | 0.7 |
| EP-1615B | EP-1615 | 2 1/4 | 1 1/2 | 2 3/4 | 0.9 |
| EP-2517B | EP-2517 | 3 3/8 | 1 3/4 | 4 1/8 | 2.2 |
| EP-2525B | EP-2525 | 3 3/8 | 2 1/2 | 4 1/8 | 3.2 |
| EP-3030B | EP-3030 | 4 1/4 | 3 | 5 1/8 | 5.8 |
| EP-3535B | EP-3535 | 5 | 3 1/2 | 6 1/4 | 11.3 |
| EP-4040B | EP-4040 | 5 3/4 | 4 | 7 1/4 | 17.3 |
| EP-4545B | EP-4545 | 6 3/8 | 4 1/2 | 7 7/8 | 21.9 |
Material and keyseat dimensions
The adapter table provides outside-diameter references for Class 20 gray iron, Class 30 gray iron and steel, plus a keyseat dimension. Those choices affect the component being adapted and the available wall section. Specify the component material and intended adapter material when a conversion is not already defined by a drawing.
Typical retrofit situations
Adapters can be used when a straight-bore sprocket, pulley or fabricated hub needs to join a taper-bushing system without machining a new taper directly in the component. They are especially useful in field retrofits where the driven part is still serviceable but the shaft connection needs to become removable or standardized.
Installation and engineering checks
Verify the straight-bore component is concentric and has enough material for the adapter outside diameter. Check the adapter keyseat, bushing model, shaft bore and axial length, then inspect final runout/alignment after assembly. A conversion should be reviewed as a new hub assembly, not simply as an added sleeve.
Frequently asked questions
Can an adapter convert any straight-bore pulley to Taper Lock?
No. The component must have suitable bore size, wall section, material and geometry for the selected adapter and load.
How do I choose between EP-2517B and EP-2525B?
They match different bushing widths even though some outside dimensions are similar. Use the matched bushing number and the full A/B/C dimensions.
Related products and resources
Need help with a real application?
Send the model, shaft diameter, keyway or drawing so the enquiry can be checked against the correct bushing family.