Husqvarna 596278501 3-Tooth Grass Knife OEM for 536 LiRX 578444901 537149001

What It Is

This is the OEM 3-tooth grass knife (part #596278501) for Husqvarna 536 LiRX string trimmers and brushcutters (models 578444901 and 537149001). It replaces the standard cutting head with a steel blade for heavy-duty clearing of thick grass, weeds, and light brush.

Fitment & Compatibility

Direct fit for: Husqvarna 536 LiRX (578444901) and 537149001 models.
What to check before buying:

• Confirm your trimmer model number on the unit’s serial tag (not just the brand).
• This is an OEM Husqvarna part, not aftermarket – same fit and quality as the original.
• The blade measures 10 inches across (3-tooth star pattern) with a 25.4mm center hole.
• Will not fit standard string trimmer heads or most other Husqvarna models without the same mounting system.
• If your trimmer uses a bump-feed head, you’ll need to remove it and install the blade adapter (sold separately if not included).

Key Things to Know

• Quality: OEM steel blade – tougher than nylon string for thick growth, but will dull on rocks or dirt. Can be resharpened with a file.
• Installation: Moderate difficulty – requires removing the string head and installing the blade with the correct washer and nut (torque to 20-25 ft-lbs). Use thread locker if not factory-applied.
• Safety: Always wear eye and leg protection. The blade can kick back on solid objects. Never use above waist height.
• Common gotcha: The blade is reversible – flip when one side wears. Inspect for cracks after each use; replace if damaged.

Should You Buy It

Yes, if you own a Husqvarna 536 LiRX (578444901 or 537149001) and need to clear heavy grass, brambles, or saplings where string would shred or tangle. It’s a direct OEM replacement that’s cheaper than a new trimmer head, but skip it if you only mow light grass – string is safer and easier.