Lawn Mower Deck

[MJM]

The build-up of grass underneath is actually an aid to not wearing through the deck in operation. It is counter-intuitive--but the impact of millions of almost massless grass clippings at high speed off the blades is the culprit. Wind turbine blades are a huge problem with dust impacts. I see this a lot with transfer movement of very soft materials like polystyrene bead or sawdust. Once you get a buildup on the stationary part the impact/abrasion is against like material and the buildup acts as a cushion. Welded hard facing bead patterns on a lot of earthmoving equipment is the same principle--you trap dirt on the blade and moving dirt only contacts this buildup.

No fooling you, you speak the truth, however.......with regards to the buildup of grass clipping on the underside of the deck. I absolutely agree it provides protection. I will let the grass build up under the deck until I start to see "hay rows" on top of the cut grass. The hay rows form when the build up of grass under the deck has no more room and expels the grass clippings downwards forming the hay row look.

It might take half a season of cutting to build up under the deck before needing to be cleaned.