What Are Cone Lock Nuts?
Cone lock nuts—also called Stover lock nuts or all-metal prevailing torque nuts—use a conical, distorted-thread section at the top of the nut to create friction on the bolt’s threads. This built-in interference produces a reusable, high-vibration lock without nylon inserts or liquid threadlocker, and it continues to hold at elevated temperatures.
Key Benefits of Cone Lock Nuts
- Vibration resistance: Prevailing torque keeps joints tight where standard hex nuts can loosen.
- All-metal design: No nylon to soften or degrade in heat, oils, solvents, or UV.
- Reusable in many assemblies: Elastic thread distortion provides repeatable locking (replace in critical service if torque falls outside spec).
- Simple, one-piece solution: No separate lock washer or adhesive required.
Cone Lock Nut Materials & Grades
- Zinc-plated carbon steel: Economical corrosion protection for dry, indoor, or sheltered outdoor use.
- Plain (black) carbon steel: Best where finish is not required or parts will be coated post-assembly.
- Metric DIN 980V / Imperial Grades: Offered across common strength classes to match your bolt grade. Always pair nut strength with the fastener’s grade.
Common Applications for Cone Lock Nuts
- Automotive, truck, and off-highway equipment
- Industrial machinery and vibration-prone assemblies
- Construction hardware and structural fittings (non-welded joints)
- Aerospace/industrial panels, guards, and fixtures
How to Install Cone Lock Nuts
- Orient the nut with the conical, distorted end up (away from the bearing surface).
- Run the nut down by hand until resistance from the prevailing torque is felt.
- Tighten to the specified torque using a wrench or socket. Do not lubricate unless your specification provides adjusted torque values.
- For safety-critical joints, verify prevailing-torque values on first installation and after any reuse.
How to Select the Right Cone Lock Nut
- Match thread size & pitch: e.g., 1/4-20, 3/8-16, M10-1.5.
- Match strength class: Choose a nut grade that equals or exceeds the bolt grade.
- Choose finish for environment: Zinc-plated for general use; plain steel for post-coating or dry interiors.
- Temperature & chemicals: Use all-metal cone locks where nylon insert nuts are unsuitable.