Lawn mowers, particularly riding lawn mowers, are available with a number of blade options. In the 1980s, lawn mowers were marketed with a “mulching blade” that was advertised as a way to eliminate the need to collect lawn clippings in bags. Because these blades did not perform well, the mulching blade was redesigned into what is now called a hi-lift blade for lawn mowers and riding tractors.
Lawn Tractor Blades
The lawn mower blade rotates at high speed to cut the grass blades. The rotating blade creates an airflow that ejects the grass clippings from under the mower deck. Grass is thrown onto the lawn or into an attached grass catcher assembly. But grass catchers tend to get clogged with moist heavy clippings, causing them to lose their effectiveness. So lawn mower design engineers have attempted to create a new system, the hi-lift blade, to solve this problem.
Standard Lift Blades
Standard lift mower blades create a wind stream that ejects the grass from under the mower deck. If a mower with a standard blade is operated without a grass catcher, the mower creates clumps of grass throughout the yard. The problem is that these grass clippings are manually raked and removed from the lawn so that they do not kill the grass, or leave unsightly piles of grass clippings throughout the yard. When grass catchers are used with traditional blades, the pieces of grass in the clippings are still large, moist and heavy enough to clog the discharge chute, thereby limit the value of the grass catcher.
Hi-lift blades are designed to take advantage of aerodynamics engineering. The blade is shaped to create an upward draft under the mower deck. As a result, the individual blades of grass are sucked upward before they're cut. The result is a better, more even cut. The upward airflow also pulls the blade clippings upward, giving the lawn mower blade another opportunity to cut the clippings into smaller bits before they are ejected.
Advantages of a Hi-Lift Blade
Because the high lift blade pulls the blades of grass upward, it cuts the grass more evenly. As the upward airflow suspends the grass clippings under the mower deck, the clippings are chopped into smaller bits before exiting the deck via the discharge chute. The chopped grass clippings are finely mulched. Therefore operators do not need to use a bagging system. If a bagging system is used, the smaller grass clippings are less likely to clog the discharge chute, which makes the bagging system more effective.