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Holes in Bolt and Screw Shanks and Slots in Nuts for Cotter Pins (SAE J485-2016)
🛠️ Standard Status: SAE J485-2016 has been declared “Stabilized” by the SAE Fasteners Committee, meaning it covers mature technology unlikely to change in the foreseeable future. Users are responsible for verifying continued suitability and references.
Scope and Purpose of SAE J485
SAE J485 specifies the dimensional requirements for holes in bolt and screw shanks and slots in nuts intended to accommodate cotter pins. The standard ensures that these features are properly sized and toleranced to allow reliable assembly and locking of threaded fasteners. By providing uniform dimensions, it promotes interchangeability between components from different manufacturers. The standard applies to a range of fastener sizes and thread series, and its guidelines are critical for applications where vibration or loosening must be prevented.
Dimensional Requirements and Tolerances
The standard defines hole diameters for bolt and screw shanks as well as slot widths and depths in nuts, all correlated to the nominal thread size and the intended cotter pin diameter. Tolerances are provided to ensure a snug fit without being overly tight, which could make assembly difficult. Below is a representative excerpt of the dimensional tables found in SAE J485 (for illustration; refer to the current standard for complete data).
| Nominal Thread Size | Cotter Pin Diameter | Hole Diameter in Shank (min–max) | Slot Width in Nut (min–max) | Slot Depth |
|---|---|---|---|---|
| 1/4 – 28 UNF | 0.062 in (1/16) | 0.064 – 0.073 in | 0.060 – 0.070 in | 0.150 – 0.170 in |
| 5/16 – 24 UNF | 0.078 in (5/64) | 0.080 – 0.089 in | 0.076 – 0.086 in | 0.180 – 0.200 in |
| 3/8 – 24 UNF | 0.094 in (3/32) | 0.096 – 0.105 in | 0.090 – 0.100 in | 0.220 – 0.240 in |
| 7/16 – 20 UNF | 0.109 in (7/64) | 0.112 – 0.121 in | 0.105 – 0.115 in | 0.260 – 0.280 in |
⚠️ Common Mistakes: Using a hole diameter that is too small can make assembly of the cotter pin impossible, while an oversized hole may not securely lock the pin. Always verify tolerances against the cotter pin size specified in J485. Do not assume that a single hole size fits all fasteners of a given thread series; always consult the exact standard table.
Engineering Design Insight
🔍 SAE J485 represents a mature and stable design practice that has been used for decades to secure clevis pins, bolts in linkages, and other safety‑critical connections. The standardized hole and slot dimensions ensure that cotter pins can be installed consistently and deliver reliable retention. When designing new assemblies, engineers should reference J485 early in the process to avoid costly rework. Because the standard is stabilized, it remains a trusted resource without frequent changes, but users should confirm that other referenced documents (e.g., ASME B18.10 for cotter pins) are still current.
Frequently Asked Questions
What is SAE J485?
SAE J485 is a surface vehicle standard that covers the dimensions of holes in bolt and screw shanks and slots in nuts for cotter pins. It is published by SAE International.
Why was SAE J485 stabilized?
The standard was stabilized because the underlying technology is mature and not expected to change. No further periodic reviews for currency will be performed; users must verify that the standard remains suitable for their application.
What are the key dimensional requirements?
The standard specifies hole diameters, slot widths, slot depths, and tolerances for various thread sizes, all designed to match standard cotter pin diameters. These dimensions ensure a secure fit that resists loosening under vibration.
How do I ensure proper fit of a cotter pin in a bolt or nut?
First, select the appropriate cotter pin size as specified in the standard for your thread size. Then machine the hole or slot to the given tolerances. Finally, install the cotter pin by spreading its ends to lock the assembly. Always inspect for burrs that could interfere with assembly.
