DIN 937 specifies the dimensions and tolerances for thin castle nuts (din 937). The full dimensional table is reproduced below, followed by the DIN, ISO and ASME parts that match or supersede it.
- Standard
- DIN 937
- Product
- Thin Castle Nuts (DIN 937)
- Governing standards
- DIN 937
Equivalence between national standards is dimensional, not always metallurgical. Check the property class separately when substituting.
The table below lists the dimensions catalogued for thin castle nuts (din 937) under DIN 937. The scope of DIN 937 itself is not summarised here — where a figure matters, confirm it against the published document.
DIN 937 — Scope
The table below lists the dimensions catalogued for thin castle nuts (din 937) under DIN 937. The scope of DIN 937 itself is not summarised here — where a figure matters, confirm it against the published document.
Tolerance & Product Grades
Product grade is a concept from dimensional fastener standards and does not apply to DIN 937. Tolerances for this part are the limits shown against each dimension in the table.
Dimensions Specified by DIN 937
| Thread size | Pitch (mm) | Width across flats s (mm) | Total height m (mm) | Height vs DIN 935 | Slot width n (mm) | Split pin size | Reference standard |
|---|
| M10 | 1.5 | 17.0 | 8.0 | approx. 70% | 2.8 | 2.5 x 30 | DIN 937 |
| M12 | 1.75 | 19.0 | 10.0 | approx. 71% | 3.5 | 3.2 x 36 | DIN 937 |
| M16 | 2.0 | 24.0 | 13.0 | approx. 76% | 4.5 | 4 x 40 | DIN 937 |
| M20 | 2.5 | 30.0 | 16.0 | approx. 80% | 4.5 | 4 x 50 | DIN 937 |
| M24 | 3.0 | 36.0 | 19.0 | approx. 79% | 5.5 | 5 x 63 | DIN 937 |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Thin Castle Nuts (DIN 937) page.
Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
When to Specify DIN 937
DIN 937 is still widely used in European mechanical engineering and as a cross-reference on legacy drawings; its ISO equivalent is preferred for new designs.
Custom manufacturing · Made to drawing
Need a nut to this standard in a non-standard size?
Parts built to DIN 937 are already in the catalog, so a special is usually a variation on existing tooling rather than a new design — which is what keeps the cost down. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
Custom nut manufacturingSend a drawing
Applications & Industries
Thin Castle Nuts are bought for a small number of well-defined jobs. These are the ones we ship them for. Stocked from M10 to M24.
Industries that specify Thin Castle Nuts
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Rail & heavy equipment
Inspectable, positively locked joints.
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Automotive chassis
Wheel bearings, steering and suspension joints locked by a split pin.
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Agricultural & plant
Articulating joints not meant to be torqued solid.
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Steel fabrication
Bolted structural and frame connections.
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Automotive & transport
Vibration-prone joints where the locking type is specified on the drawing.
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Maintenance & MRO
Replacements matched to the existing bolt class, thread and finish.
Typical applications
- tighten to torque, then back off to the nearest slot
- positive locking with a split pin through a cross-drilled bolt
- joints deliberately left free to articulate
- joints re-torqued at a service interval
- completing a bolted joint on a stud, rod or bolt
- locking an adjustment so it cannot drift
Service conditions to specify against
- Marine and coastal
- Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
- High load
- Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
- Match the class
- A nut below the bolt property class strips before the bolt reaches its own limit — pair class 8 nuts with 8.8 bolts, class 10 with 10.9.
Full application guide: where Thin Castle Nuts are used, how to specify them, and the cases they are wrong for
