When you buy a walk-behind lawnmower, you benefit from safety standards and regulations from two sources.
 
The American National Standards Institute (ANSI) has issued ANSI B71.1, Walk-Behind Mowers and Ride-On Machines with Mowers - Safety Standards. This ANSI standard was developed by engineers within the lawnmower industry and most manufacturers adhere to this standard. If a mower has been certified by an independent testing facility to comply with ANSI B71.1, the mower will carry a decal from the Outdoor Power Equipment Institute (OPEI) certifying compliance.

The United States Consumer Product Safety Commission (CPSC) has also issued regulations for walk-behind lawn mowers. Unlike the ANSI consensus standard, the CPSC regulations are not optional; manufacturers are required to comply. Some of the important features of the ANSI standard and CPSC regulations are listed below.

Operator Presence Control (OPC)
Mowers must be equipped with some type of handle-mounted control bar or lever (Figure 1). The operator must hold the bar or lever in place for the engine and/or blade to operate. On less expensive mowers, releasing the bar or lever stops the engine and the blade; on more expensive mowers, releasing the lever disengages a clutch, allowing the engine to remain running while the blade is stopped.

Actuation of OPC
The mower must have a secondary control that must be activated before the OPC can be engaged. This is often a thumb lever that must be depressed.

Blade Brake Control
A mower must be equipped with a brake to stop the blade within three seconds after the operator presence control is released. This is to prevent an operator from leaving the operator position behind the handle and coming around close to the deck while the blade is running.

Restarting
If the mower has a manual starter, releasing the operator presence control must allow the engine to remain running unless the manual starter is located within 24 inches of the top of the handle (unless the mower has a 360-degree foot shield) (Figure 2).

Foot Shield
The rear of the mower must be shielded by either a flexible shield or a hinged solid flap to prevent a foot from being inserted under the deck (Figure 3). If the shield must be opened or removed to install a grass catcher or mulching plate, there must be either automatic closure or a switch to prevent blade operation when open.

Labels
Several safety warning labels are required on mowers.

Thrown Objects
The ANSI standard requires testing of mowers for potential to throw objects from under the deck. A whole series of tests assure that mowers are safe when the blade encounters objects.

Other
The ANSI standard also covers many other safety areas such as shielding for power drives, direction of operation of self-propulsion controls, heat protection, fuel ignition protection, battery safety, etc.

Some of the above items may be frustrating to work with, and they may not always work well, but they are there for one reason - to protect you! Please don’t disconnect or try to work around these safety features!