26
Perform Maintenance Safely

Mower Blade Maintenance (continued)

— How are mower blades made?
Mower blades are made of high strength alloy spring
steel. They are hot-forged and shaped to meet the
manufacturer’s individual speci cations, then heat
treated and tempered to a high strength, ductile state
to reduce the possibility of breaking while mowing.
Blades are tested to ensure they meet strength,
hardness, and ductility standards. If a blade fails to
meet any of these speci cations, it will not be used
on the mower.
— What happens when a mower blade bends?
It takes a great amount of impact force to bend
the blade. This impact force often results in the
blades being gouged or chipped. After a blade
is damaged by a gouge or chip a blade failure is
much more likely to occur. When a blade is severely
bent, a microscopic crack may be created in the
blade. Straightening the blade does not remove or
repair this crack, but may cause additional cracks.
Additional stresses during mowing operations can
result in an unexpected blade failure.
— Avoid bending blades. Help prevent mower blades
from bending or cracking by avoiding contact with
solid objects. Mower blades are intended to cut
grass, shrubs, woody vegetation, and small trees and
limbs. They are not intended to contact solid objects
such as rocks, concrete, or steel posts. Inspect the
area prior to mowing. Remove or clearly mark any
solid objects and mow around them.
— Replace damaged blades! Inspect the mower blade(s)
daily or after hitting any solid object. If a mower blade
becomes damaged (bent, gouged, cracked) or worn
more than 25 percent of the original size, it should
be removed and replaced with a new blade. Always
use the original manufacturer’s blades. Aftermarket
brand blades may not meet the mower manufacturer’s
strength, hardness and ductility requirements.
— Do not take chances mowing with damaged or
bent blades. Using a damaged or straightened
mower blade can result in the blade breaking and
being thrown into the operator or a bystander causing
death or serious injury. The price of a new blade is
small compared to the potential for the serious injury
that could result from a bent or broken blade being
thrown from the mower.
Final Word To The User
You have just  nished reading the AEM Industrial and
Agricultural Mower Manual. It is impossible for this
manual to cover every safety situation that you may
encounter on a daily basis. Your knowledge of these
safety precautions and your application to the
basic rules of safety will help to build good judgment
in all situations. Our objective is to help you develop,
establish and maintain good safety habits to make
operating an Industrial and Agricultural Mower easier
and safer for you.

This manual is another in a series on the safe operation of machinery published by AEM.

Many pictorials in this safety manual can be found and downloaded at http://pictorials.aem.org.

For additional publications visit our website at www.safetymaterials.org.

ASSOCIATION OF
EQUIPMENT MANUFACTURERS
e-mail safetymaterials@aem.org
www.aem.org