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Hex lock nut with free-spinning washer, zinc steel finish

MIDWEST FASTENER CORP

MIDWEST FASTENER CORP 09650 Free Spinning Washer Lock Nut 5/16"-18 Steel Zinc

SKU CH-3G3E-64AHH

A free-spinning washer lock nut with 5/16"-18 threads, made from zinc-plated steel to resist loosening under vibration

  • Product typeNuts
  • Free-spinning washer resists vibration loosening
  • 5/16"-18 thread fits matching bolts
  • Steel core delivers structural strength
  • Zinc coating protects against corrosion
  • New condition ensures full factory performance

Purpose and fit

The MIDWEST FASTENER CORP 09650 is a free spinning washer lock nut built for 5/16"-18 threads. It suits mechanics and fabricators who need a single steel zinc fastener that resists loosening under vibration and torque. The integrated washer distributes clamping force without a separate flat washer. Buyers who need a different thread pitch or a non-locking hex nut should look elsewhere.

Behaviour under load

The lock nut resists loosening when subjected to sustained vibration and torque rather than only brief impact. Its free spinning washer turns independently to maintain clamp load while the prevailing torque feature holds the nut in position. The steel zinc construction provides consistent friction characteristics through repeated thermal cycles. No lubrication or re-torque schedule is specified by the manufacturer.

Deciding specification

The thread call-out 5/16"-18 is the single specification that determines whether this part fits the application. Only hardware cut to that exact diameter and pitch will engage correctly. The 9650 model number identifies this specific lock nut style within the MIDWEST FASTENER range. Verify the thread requirement before ordering.

How it compares

Measured against everything we stock in General Hardware & Accessories, at today’s prices. Recalculated every night.

Price $35.99
Pricier than about 66% of the 2,607 comparable items (median $18.99).

Specifications

Product
Brand nameMIDWEST FASTENER
Product typeNuts

Questions about this item

Does the free-spinning washer on the 09650 lock nut generate extra heat or noise when left under constant vibration all day?

The free-spinning washer is designed to resist loosening under vibration and torque without adding measurable heat or noise during continuous operation.

What thread size must the mating bolt or stud have for the 5/16"-18 lock nut to engage properly?

The nut requires a 5/16"-18 thread on the bolt or stud for correct engagement.

Will the zinc-plated steel 09650 lock nut gall or corrode when paired with older plain-steel or galvanised hardware?

Zinc plating provides a sacrificial barrier that reduces galvanic corrosion and galling when used with plain-steel or galvanised fasteners.

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