For a replacement coupling, “same as the old one” is not a dimension. Measure the shaft or use the equipment drawing. Do this on both sides; motor and driven shafts are often different.
Record these dimensions
| 物品 | 需要确认什么 |
|---|---|
| Shaft diameter | Measure the actual shaft; note the unit and required fit if controlled. |
| Keyway width and depth | Use the shaft drawing where possible. If measured, state that the values are field measurements. |
| Hub length available | Check shoulders, seals, guards and nearby equipment. |
| Shaft end position | Note how far the shaft enters the hub and any axial gap requirement. |
| Setscrew or locking detail | Photograph and dimension it if the replacement must match an existing arrangement. |
Why a photo is not enough
Perspective can make a 28 mm and 30 mm bore look identical, and an assembled guard can hide the hub length. Photos are excellent for identifying construction and damage; dimensions are what make the part fit.
