Cotter pin | A4 | DIN 94
Stainless steel A4 split pin/cotter pin is intended for use in corrosive and marine environments. The product is used for the mechanical locking of bolts, pins, or shafts by preventing axial movement and accidental loosening. Its design allows for easy installation by inserting it into a pre-drilled hole and subsequently bending the legs for secure fastening. It is suitable for installations where high corrosion resistance, reliable locking, and easy removal during service are required.
AREA OF USE
The product is used in marine equipment, machinery installations, vehicles, structural construction, and outdoor applications. It is intended for applications where secondary locking of bolted joints is required, such as in hole bolts, shafts, pin joints, and shackles. The choice of material provides resistance to saltwater, moisture, and chemically aggressive environments, making it suitable for long-term exposure without loss of function.
TECHNICAL SPECIFICATIONS
Product type: Pin
Product family: Split pin
Material grade: A4
Strength class: Not specified
Standard: DIN 94 / ISO 1234
Diameter: 1.6–6.3 mm
Design: Split pin
Surface finish: Bright
Environment: Marine
Unit of sale: Piece
FREQUENTLY ASKED QUESTIONS (FAQ)
What is the primary function of a split pin (DIN 94 / ISO 1234)?
A split pin (also known as a cotter pin) is a classic and extremely reliable mechanical locking element:
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Prevents axial movement: It is inserted into a through-hole in a bolt, clevis pin, threaded rod, or shaft and locks the component so that it cannot slide out of position.
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Locking of castle nuts: Often used in conjunction with castle nuts (DIN 935) on rotating shafts or steering linkages, where the pin prevents the nut from unscrewing due to vibration.
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Clear visual inspection: You can quickly and easily verify visually that the legs are bent and the lock is securely in place.
Why is acid-proof steel A4 (AISI 316) crucial for split pins in marine environments?
A split pin is subjected to both bending stress during installation and constant environmental impact. Using the wrong material can have disastrous consequences:
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Resists crevice corrosion and chlorides: A4 steel (1.4401 / AISI 316) provides excellent protection against pitting and crevice corrosion in humid areas, road salt, and direct marine environments (rigging, rudders, and deck equipment).
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Avoids cracks during bending: Cheaper or unsuitable steel types can become brittle or suffer from stress corrosion when the legs are bent. Acid-proof A4 steel retains its ductility and toughness so that the legs can be bent without cracks occurring.
How do you properly install and size a split pin?
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Correct hole diameter: Select a pin whose nominal diameter fits the hole. Note: A split pin is specified according to the hole it is intended for, while the actual leg diameter of the pin is slightly smaller to allow for smooth insertion.
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Correct bending of the legs: Once the pin has been pushed all the way through the hole (until the rounded eyelet touches the surface), the two legs are bent in opposite directions:
- The long leg is usually bent over the end of the bolt/shaft.
- The shorter leg is bent downwards along the side of the bolt.
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Single-use component for safety: Since the material becomes fatigued and weakened when bent back and forth, you should always replace it with a new A4 split pin when the assembly is dismantled for service or maintenance.