Two Way Lock Nuts
What Are Two Way Lock Nuts?
Two Way Lock Nuts—also called reversible lock nuts or centerlock all-metal lock nuts—use deformations in the center of the hex to create prevailing torque on the mating screw or bolt. Because the locking feature is in the middle of the nut (not at one end), they can be installed from either direction, making them “two way.” As an all-metal solution, they are heat-resistant and ideal where nylon insert nuts are not suitable.
Key Benefits of Two Way Lock Nuts
- Reversible installation: Installs top-up or top-down to speed assembly lines.
- All-metal prevailing torque: No nylon; maintains lock under heat and chemicals.
- Compact length: Locking occurs in the center, so the nut needn’t extend past the bolt end.
- Vibration resistance: Positive friction on threads helps resist loosening in dynamic loads.
- Reusable (limited): Can be reused a few times; replace once prevailing torque drops.
Materials & Finishes for Two Way Lock Nuts
- 18-8 (304) Stainless Steel: General corrosion resistance for outdoor and damp environments.
- 316 Stainless Steel: Enhanced resistance for marine/salt spray and aggressive environments.
- Zinc-Plated Steel: Economical indoor use with light corrosion protection.
Common Applications for Two Way Lock Nuts
- Equipment and machinery where vibration resistance is required
- Automotive, transportation, and conveyor systems
- Electrical panels, enclosures, and racking
- Construction fastening where heat or solvents rule out nylon inserts
Installation Tips for Two Way Lock Nuts
- Start by hand to prevent cross-threading, then tighten with a correctly sized wrench or socket.
- Follow torque guidance for the bolt size and grade; over-torque can reduce prevailing torque and service life.
- For coated or painted parts, use a flat washer to protect finishes.
- Recheck joint torque after first run-in cycles if the assembly sees vibration.
How to Select the Right Two Way Lock Nuts
- Match thread and diameter: Ensure the nut’s thread pitch and size match your bolt/screw.
- Choose material for environment: Zinc-plated for dry indoor; 18-8 for outdoor; 316 for marine.
- Consider service temperature: Pick all-metal two way lock nuts for high heat where nylon fails.
Frequently Asked Questions about Two Way Lock Nuts (FAQ)
The locking deformations are in the center of the nut, so it can be installed from either side with the same locking action.
Use two way lock nuts in high-temperature, chemical, or solvent-exposed applications where nylon can soften or degrade, or when you want faster, reversible installation.
Limited reuse is fine, but prevailing torque decreases with cycles. Replace the nut if it spins too easily or no longer holds torque under vibration.
Follow the bolt’s size/grade torque charts and consider joint materials. Over-torque can flatten the locking deformations and reduce effectiveness.
They can mark finishes under high torque. Add a flat washer or finish-friendly washer if appearance matters.
Zinc-plated steel for dry indoor; 18-8 stainless for general outdoor; 316 stainless for marine and severe corrosion.
Yes. They work with threaded studs, bolts, or machine screws as long as the threads and pitch match.
Both are all-metal prevailing-torque designs. Top-lock deforms at one end (one-way), while two way centerlock deforms in the middle (reversible); pick based on installation preference and clearance.