Types of retaining ring
Five types cover almost everything. The choice is usually decided by how much room there is and whether the assembly has to come apart again.
| Type | Fits | Notes |
|---|---|---|
| External, DIN 471 | Groove on a shaft | Sized by shaft diameter; needs external circlip pliers |
| Internal, DIN 472 | Groove in a bore | Sized by bore diameter; needs internal circlip pliers |
| E-clip | Groove on a shaft, fitted radially | Slides on from the side; no pliers, low thrust capacity |
| Spiral, two-turn | Groove on shaft or in bore | No lugs, full 360° contact, higher thrust, no pliers |
| Constant section | Groove on shaft or in bore | Uniform section, cheap, lower capacity |
External retaining ring sizes
Cut the groove to the diameter and width given, not to the ring thickness. The groove is deliberately slightly wider than the ring so it can seat, and slightly shallower than half the ring width so the ring stands proud enough to take thrust.
| Shaft dia | Ring thickness | Groove dia | Groove width |
|---|---|---|---|
| 8 | 0.80 | 7.60 | 0.90 |
| 10 | 1.00 | 9.60 | 1.10 |
| 12 | 1.00 | 11.50 | 1.10 |
| 15 | 1.00 | 14.30 | 1.10 |
| 20 | 1.20 | 19.00 | 1.30 |
| 25 | 1.20 | 23.90 | 1.30 |
| 30 | 1.50 | 28.60 | 1.60 |
| 35 | 1.50 | 33.00 | 1.60 |
| 40 | 1.75 | 37.50 | 1.85 |
| 45 | 1.75 | 42.50 | 1.85 |
| 50 | 2.00 | 47.00 | 2.15 |
| 60 | 2.00 | 57.00 | 2.15 |
Fitting and removing
Use the right pliers. External and internal circlip pliers open in opposite directions and are not interchangeable; forcing the wrong pair distorts the ring and it will not seat.
Do not over-expand. A circlip opened past its elastic limit loses its grip permanently, and a ring that has been stretched will creep out of the groove under vibration. If a ring has been off once and looks opened up, replace it.
The sharp edge from stamping goes away from the load. On a DIN 471 ring the rounded face carries the thrust, so fit the sharp-edged side facing out.
