Are Split Lock Washers Necessary with Lock Nuts?

Emily Jul 26, 2026

You might have heard that using a lock nut in conjunction with a split lock washer is an industry standard. But is it truly necessary? Let's explore the mechanics behind this combination and understand when it's crucial and when it's not.

What Is A Lock Washer 2022 (Guide)
What Is A Lock Washer 2022 (Guide)

In many applications, a lock nut and a split lock washer are used together to prevent loosening under vibration and torque. But before delving into detail, let's first understand what these components are.

Quick Access: Spring Washer Weight Chart In Kg, Mm, Pdf (free Download)
Quick Access: Spring Washer Weight Chart In Kg, Mm, Pdf (free Download)

What is a Split Lock Washer?

Simply put, a split lock washer is a flat washer with an internal notch. This notch is designed to bite into the fastened material when tightened, preventing it from loosening due to vibration or thermal cycling.

Midwest Fastener 1 In. x 1-5/8 In. Zinc Plated Grade 5 Steel Split Lock Washers (116 Ct.)
Midwest Fastener 1 In. x 1-5/8 In. Zinc Plated Grade 5 Steel Split Lock Washers (116 Ct.)

Split lock washers come in various sizes and materials, including steel, brass, and aluminum, each with its unique properties and use-cases.

What is a Lock Nut?

480 stuks 304 roestvrijstalen veerringen set M2-M12 borgring in compacte doos corrosiebestendig
480 stuks 304 roestvrijstalen veerringen set M2-M12 borgring in compacte doos corrosiebestendig

A lock nut, also known as a self-locking nut, is designed to resist loosening due to vibration or torque. The internal mechanism of a lock nut bites into the threads of a bolt, preventing it from backing out.

Lock nuts are typically made of harder material than the bolt they're used with, ensuring they can bite into the threads without stripping them.

Why Use a Split Lock Washer with a Lock Nut?

LAMBRETTA SERIES 2 3 LI GP SX TV REAR HUB LOCK WASHER AND NUT KIT
LAMBRETTA SERIES 2 3 LI GP SX TV REAR HUB LOCK WASHER AND NUT KIT

Using a split lock washer with a lock nut fortifies the system against loosening, particularly in high-vibration or dynamic load environments.

Here's why:

  • Dual Action: Both the washer and the nut work together to resist loosening, providing redundancy. If one fails, the other might still hold.
  • Force Distribution: The washer distributes the force of the nut over a larger area, reducing the risk of stripping the bolt's threads.
Roper Washer Lid Lock Not Working (Reset/Bypass) - Ready To DIY
Roper Washer Lid Lock Not Working (Reset/Bypass) - Ready To DIY

When is it Not Necessary?

However, in low-vibration or static load environments, using both components might not be necessary.

Maytag Washer Lid Lock Bypass Guide & Tips - Machine Answered
Maytag Washer Lid Lock Bypass Guide & Tips - Machine Answered
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How to remove broken key
Midwest Fastener 9/16 In. x 31/32 In. Chrome Plated Grade 8 Steel Split Lock Washers
Midwest Fastener 9/16 In. x 31/32 In. Chrome Plated Grade 8 Steel Split Lock Washers
Midwest Fastener 9/16 In. x 31/32 In. Zinc Plated Grade 2 Steel Split Lock Washers (576 Ct.)-
Midwest Fastener 9/16 In. x 31/32 In. Zinc Plated Grade 2 Steel Split Lock Washers (576 Ct.)-
Midwest Fastener 3/8 In. x 11/16 In. Chrome Plated Grade 8 Steel Split Lock Washers (16 Ct.)-
Midwest Fastener 3/8 In. x 11/16 In. Chrome Plated Grade 8 Steel Split Lock Washers (16 Ct.)-
Midwest Fastener #10 x 3/16 In. x 21/64 In. Chrome Plated Grade 8 Steel Split Lock Washers (16 Ct.)
Midwest Fastener #10 x 3/16 In. x 21/64 In. Chrome Plated Grade 8 Steel Split Lock Washers (16 Ct.)
Getting New Locks? Here Are Some Things You Should Know - Mr. DIY Guy
Getting New Locks? Here Are Some Things You Should Know - Mr. DIY Guy
a hand pointing at a dryer box in the middle of an unfinished room that is being built
a hand pointing at a dryer box in the middle of an unfinished room that is being built

Moreover, incorrect usage can cause damage. Too much torque can strip the bolt's threads or cause the washer to deform, potentially leading to more issues.

ock Nut Alternatives

Sometimes, other solutions can achieve the same results as a lock nut and a split lock washer.

Alternative methods include:

  • Threaded Fastener Systems: Using a locking bolt with a jam nut, where the bolt's threads are designed to resist loosening.
  • Polymer Locking Nuts: These use a flexible polymer insert to resist loosening. They can be a grease-friendly option.

In conclusion, whether or not you need a split lock washer with a lock nut depends largely on the specifics of your application. Always consider vibration loads, material properties, and torque requirements. If in doubt, consulting with a mechanical engineer can provide tailored advice.