When you need Swing Bolt — GB/T 77 / ISO 4026 (Series 020) in the M20 size, the controlling values come from GB/T 77 / ISO 4026. This page lists them in one place — pitch, head geometry, tool size and the matching hole.
M20 Dimensional Row (GB/T 77 / ISO 4026)
| Thread size | Pitch (mm) | Ring outer dia D (mm) | Ring wire dia (mm) | Total length L (mm) | SWL (kg, axial) | Reference standard |
|---|---|---|---|---|---|---|
| M20 | 2.5 | 40 | 16 | 72 | 1200 | DIN 580 / GB/T 825 |
Spanner & Drive for M20 Swing Bolt — GB/T 77 / ISO 4026 (Series 020)
Drive geometry for M20 Swing Bolt — GB/T 77 / ISO 4026 (Series 020) is given by the row above; match the tool to the listed values.
Hole Sizes for M20
| Coarse-thread pitch (ISO 724) | 2.5 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 22 mm |
| Tapping drill, coarse thread | 17.5 mm |
Tightening Torque for M20
| Class 8.8 (dry, ~µ 0.125) | ≈ 410 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 580 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 690 Nm |
Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class.
Common Applications for M20 Swing Bolt — GB/T 77 / ISO 4026 (Series 020)
M20 Swing Bolt — GB/T 77 / ISO 4026 (Series 020) are commonly specified for structural steelwork, heavy machinery foundations and large flange joints.
Mating Parts for M20
For M20, pair with a M20 hex nut (ISO 4032 / DIN 934) and, where used, a M20 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
When to Step Up or Down from M20
When the joint preload approaches the proof load of M20 class 8.8, step up to M24 class 8.8 (or move to M20 class 10.9). When the joint is over-specified, M16 often saves weight and cost without losing the safety margin.