How to maintain your commercial lawn mower deck?

A commercial lawn mower deck is made of rugged components to serve the high usage required by professional landscapers. However, parts do wear out or break. Knowing the deck components and maintaining them properly will significantly extend the life of your mower and minimize unnecessary downtime. Most deck maintenance can be done in-house.

Here are the most common lawn mower deck parts to maintain and check for wear.

Lawn Mower Blades

Lawn mower blades contact with everything from grass to rocks. Mower deck blades will become worn or damaged over time. Make sure to use the right blade for the job – low lift, high lift, or mulching.

Keep your blades sharp. Rotary lawn mower blades should be sharpened after 20 to 25 hours of usage. For commercial landscapers this means once a week or more, sometimes every day. Visually checking the blades of grass after a cut will tell you if the blade needs sharpening. Keep your blades sharp using a blade sharpener such as MowMore RGB712 to ensure a smooth, even cut.

If you must replace your lawn mower blades, be sure to choose the proper blade replacement by identifying the part # or measuring the blade. Removing a blade is a simple process of removing the bolt that secures it to the spindle. See our blog on hot to measure mower blade.

Mower Deck Spindles

Lawn mower spindles are a crucial part of the lawn mower cutting deck. The mower deck spindle works with the pulley to rotate the mower blades evenly. Bent or worn spindles will wobble and create an uneven cut and potential damage to other mower deck parts. Maintaining this assembly is crucial to long mower life and quality mowing.

Blade spindles ride on bearings that wear out over time. To check for worn spindles grab the connected pulley with two hands and try and rock it back and forth. If you feel play in the pulley it’s a sign that the spindle bearings are starting to wear out and replacement may be necessary. The pulleys should spin freely without any growling sounds which would also indicate bearing wear.

Most commercial mowers use greaseable spindles with a grease plug located on the side of the assembly. Recommendations for greasing vary from every 10 to 25 hours of usage to once a month. Check your owner’s manual for instructions and recommended grease. Spindles typically have a large grease cavity so pump until you see grease exit the weep hole.

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Commercial Mower Belts

The mower belt transfers power from the engine to the pulleys on the mower deck. You should visually inspect the belt with every 25 hours of use. A mower belt that slips on the pulleys or frays can affect cutting performance. Cracked or excessively worn belts will eventually fail so have a spare available.

To inspect the belts, follow your owner’s manual instructions. Remove the belt(s) and visually inspect for frays, cracks, or glazing. Many premature belt failures are caused by other mechanical problems such as seized pulleys or worn spindles so check the pulleys and spindles when inspecting the belt. Belt wearing can also be caused by excessive grass clippings in and around the pulleys or a missing or damaged belt guard that keeps the belts in place. So, keep the deck clean and make sure the belt guard is in place.

For the correct replacement belt for your mower, be sure to match the original belt OEM part # from your manual.

Mower Deck Pulleys

Pulleys should be checked to make sure they spin freely with no growling noises and without wobble (sign of spindle wear). Foreign objects and excessive clippings in grooves and around pulleys can also cause excessive wear.

Mower Deck Idler Tensioner Spring

Most lawn mower decks use heavy duty springs to provide tension on the belt. See your owner's manual to determine the correct spring length for your mower's deck size and how to adjust it if necessary.

Anti-Scalp Rollers

The anti-scalp rollers help keep the lawnmower deck raised. When the deck is at your cutting height, the anti-scalp wheels should be just above the ground (easy to set up on a flat hard surface) with a clearance between 1/4 and 3/8 inches. The wheels should spin freely. If you lose one, or if one becomes damaged or worn, it should be replaced.


Always make sure the underside of the deck and the area around the pulleys is clean and clear of debris to allow blades and pulleys to spin freely. Check out our video on the Grassbuster at

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