587973001 587969201 Idler Pulley Assembly Compatible With Husqvarna Craftsman Walk-Behind Lawn Mowers, for Lawn Mower Decks Idler Pulley HU725AWD/BBC, HU725AWDHQ, LC221RH Replaces Previous 581904001

What It Is

This is a replacement idler pulley assembly (part numbers 587973001 / 587969201) designed for Husqvarna and Craftsman walk-behind mowers. It keeps tension on the deck belt so the blade engages properly, and it’s commonly needed on Honda-powered HU725 and LC221 series mowers.

Fitment & Compatibility

Check these before buying:

• Deck size: Fits 46-inch and 54-inch fabricated decks on Husqvarna HU725AWD/BBC, HU725AWDHQ, and Craftsman LC221RH models.
• OEM vs aftermarket: This is an aftermarket replacement for original part 581904001. It matches OEM dimensions but is not a genuine Husqvarna/Craftsman part.
• Measurements: The pulley has a 3.5-inch outer diameter and a 0.5-inch bore. Measure your old pulley’s diameter and shaft hole to confirm.
• Belt compatibility: Works with standard 1/2-inch-wide deck belts. Verify your belt width and length are correct for your deck.
• Mounting: Uses a hex bolt (typically 5/16-18) and a lock washer. Check that your existing bolt threads are clean and not stripped.

Key Things to Know

• Quality: Users report it’s a solid aftermarket option—steel pulley with a sealed bearing. Not as heavy-duty as OEM but fine for residential use.
• Installation: Easy if you have basic tools (socket wrench, possibly a pry bar to relieve belt tension). Takes about 15 minutes.
• Common gotcha: The bearing is pre-greased and sealed—do not oil it. If it’s seized on removal, you may need to replace the mounting bolt as well.
• Fitment note: Some users on older decks (pre-2015) report the bolt hole is slightly smaller; you may need to ream it to 0.5 inches or use a smaller bolt.

Should You Buy It

If you need a budget-friendly, reliable idler pulley for a Husqvarna or Craftsman walk-behind with a 46- or 54-inch deck, this is a solid pick. It’s not heavy-duty enough for commercial mowing, but for home lawn care it’s a good value at $15.99. Double-check your deck model and pulley measurements before ordering.