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Small semicircular metal key with protruding tab, silver finish

MIDWEST FASTENER CORP

MIDWEST FASTENER CORP 73207 Woodruff Key 1/4 x 9/16 in Key Size 21 SAE Number

SKU CH-DYST-S5J58

A semicircular woodruff key that locks pulleys or gears to a shaft by fitting a matching keyway and slot

  • Prevents shaft rotation with half-moon key design
  • Fits 1/4 x 9/16 in keyway for secure mounting
  • SAE number 21 ensures standardised compatibility
  • Machine tool and automotive applications supported
  • New condition guarantees reliable factory performance

Woodruff Key 1/4 x 9/16 Inch

This semicircular key fits a matching shaft keyway to prevent mounted components such as pulleys from rotating independently. It serves machine tools and automotive assemblies where positive torque transfer is required. The half-moon profile seats securely in the shaft slot while the tab engages the driven device.

SAE Size 21 Standard Dimensions

The key conforms to SAE number 21 with a 1/4 inch width and 9/16 inch diameter. These fixed dimensions define the only shaft keyways and hub slots it can engage. No other size combinations are compatible with this specific part. Verify the shaft keyway width and hub slot dimensions match exactly before installation.

Shaft Keyway And Hub Slot Verification

Confirm the shaft has a correctly sized semicircular keyway and the mounted component has a matching slot for the protruding tab. The key is supplied individually without additional hardware or installation tools. Buyers needing multiple keys or an assortment of sizes must source those separately.

Highlights

  • Prevents shaft rotation with half-moon key design
  • Fits 1/4 x 9/16 in keyway for secure mounting
  • SAE number 21 ensures standardised compatibility
  • Machine tool and automotive applications supported
  • New condition guarantees reliable factory performance

Specifications

BrandMIDWEST FASTENER

Questions about this item

Should I choose the 21 SAE Number Woodruff key for my shaft?

The 21 SAE Number identifies this specific half-moon key size; match it to your shaft keyway and the mating component slot to ensure the correct fit.

How does the 1/4 x 9/16 in size affect installation?

These dimensions define the key thickness and diameter; the key seats into a matching semicircular keyway leaving a tab that locks a pulley or gear against rotation on the shaft.

What does the SAE standard cap in practice for this key?

SAE Number 21 standardises the key geometry so it fits corresponding SAE keyways, limiting interchangeability to components machined to the same specification.

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