16 CFR § 1205.5 - Walk-behind rotary power mower controls.
(a) Blade control systems -
(1) Requirements for blade control. A walk-behind rotary power mower shall have a blade control system that will perform the following functions:
(i) Prevent the blade from operating unless the operator actuates the control.
(ii) Require continuous contact with the control in order for the blade to continue to be driven.
(iii) Cause the blade motion in the normal direction of travel to come to a complete stop within 3.0 seconds after release of the control.
(A) The engine starting controls for the lawn mower are located within 24 inches from the top of the mower's handles, or
1 Paragraphs (A) and (B) of § 1205.5(a)(1)(iv), permitting mowers that stop the blade by stopping the engine but that do not have power restart, were added to the standard as directed by Sec. 1212 of the Omnibus Budget Reconciliation Act of 1981, Pub. L. 97-35, 95 Stat. 357.
(2) All walk-behind rotary power mowers shall have, in addition to any blade control required by paragraph (a)(1) of this section, another means which must be manually actuated before a stopped blade can be restarted. This additional means may be either a control which is separate from the control required by paragraph (a)(1) of this section, or may be incorporated into the control required by paragraph (a)(1) of this section as a double-action device requiring two distinct actions to restart the blade.
(b) Blade stopping test -
(i) The mower shall be operated at maximum operating speed for at least 6 minutes immediately prior to the test.
(c) Starting controls location. Walk-behind mowers with blades that begin operation when the power source starts shall have their normal starting means located within the operating control zone unless the requirements of paragraphs (a)(1)(iv) (A) or (B) of this section apply to the mowers.