(a) Upon application of its service brakes, a motor vehicle or combination of motor vehicles must under any condition of loading in which it is found on a public highway, be capable of--
(1) Developing a braking force at least equal to the percentage of its gross weight specified in the table in paragraph (d) of this section;
(2) Decelerating to a stop from 20 miles per hour at not less than the rate specified in the table in paragraph (d) of this section; and
(3) Stopping from 20 miles per hour in a distance, measured from the point at which movement of the service brake pedal or control begins, that is not greater than the distance specified in the table in paragraph (d) of this section; or, for motor vehicles or motor vehicle combinations that have a GVWR or GVW greater than 4,536 kg (10,000 pounds),
(4) Developing only the braking force specified in paragraph (a)(1) of this section and the stopping distance specified in paragraph (a)(3) of this section, if braking force is measured by a performance-based brake tester which meets the requirements of functional specifications for performance-based brake testers for commercial motor vehicles, where braking force is the sum of the braking force at each wheel of the vehicle or vehicle combination as a percentage of gross vehicle or combination weight.
(b) Upon application of its emergency brake system and with no other brake system applied, a motor vehicle or combination of motor vehicles must, under any condition of loading in which it is found on a public highway, be capable of stopping from 20 miles per hour in a distance, measured from the point at which movement of the emergency brake control begins, that is not greater than the distance specified in the table in paragraph (d) of this section.
(c) Conformity to the stopping-distance requirements of paragraphs (a) and (b) of this section shall be determined under the following conditions:
(1) Any test must be made with the vehicle on a hard surface that is substantially level, dry, smooth, and free of loose material.
(2) The vehicle must be in the center of a 12-foot-wide lane when the test begins and must not deviate from that lane during the test.
(d) Vehicle brake performance table: ----------------------------------------------------------------------------------------------------------------
Service brake systems Emergency brake
--------------------------------------------------------- systems
------------------
Braking force as Application and Application and
Type of motor vehicle a percentage of Deceleration in braking distance braking distance
gross vehicle or feet per second in feet from in feet from
combination per second initial speed at initial speed of
weight 20 mph 20 mph----------------------------------------------------------------------------------------------------------------A. Passenger-carrying vehicles:
(1) Vehicles with a seating 65.2 21 20 54
capacity of 10 persons or less,
including driver, and built on
a passenger car chassis........
(2) Vehicles with a seating 52.8 17 25 66
capacity of more than 10
persons, including driver, and
built on a passenger car
chassis; vehicles built on a
truck or bus chassis and having
a manufacturer's GVWR of 10,000
pounds or less.................
(3) All other passenger-carrying 43.5 14 35 85
vehicles.......................B. Property-carrying vehicles:
(1) Single unit vehicles having 52.8 17 25 66
a manufacturer's GVWR of 10,000
pounds or less.................
(2) Single unit vehicles having 43.5 14 35 85
a manufacturer's GVWR of more
than 10,000 pounds, except
truck tractors. Combinations of
a 2-axle towing vehicle and
trailer having a GVWR of 3,000
pounds or less. All
combinations of 2 or less
vehicles in drive-away or tow-
away operation.................
(3) All other property-carrying 43.5 14 40 90
vehicles and combinations of
property-carrying vehicles.....----------------------------------------------------------------------------------------------------------------Notes: (a) There is a definite mathematical relationship between the figures in columns 2 and 3. If the
decelerations set forth in column 3 are divided by 32.2 feet per-second per-second, the figures in column 2
will be obtained. (For example, 21 divided by 32.2 equals 65.2 percent.) Column 2 is included in the
tabulation because certain brake testing devices utilize this factor.(b) The decelerations specified in column 3 are an indication of the effectiveness of the basic brakes, and as
measured in practical brake testing are the maximum decelerations attained at some time during the stop. These
decelerations as measured in brake tests cannot be used to compute the values in column 4 because the
deceleration is not sustained at the same rate over the entire period of the stop. The deceleration increases
from zero to a maximum during a period of brake system application and brake-force buildup. Also, other
factors may cause the deceleration to decrease after reaching a maximum. The added distance that results
because maximum deceleration is not sustained is included in the figures in column 4 but is not indicated by
the usual brake-testing devices for checking deceleration.(c) The distances in column 4 and the decelerations in column 3 are not directly related. ``Brake-system
application and braking distance in feet'' (column 4) is a definite measure of the overall effectiveness of
the braking system, being the distance traveled between the point at which the driver starts to move the
braking controls and the point at which the vehicle comes to rest. It includes distance traveled while the
brakes are being applied and distance traveled while the brakes are retarding the vehicle.(d) The distance traveled during the period of brake-system application and brake-force buildup varies with
vehicle type, being negligible for many passenger cars and greatest for combinations of commercial vehicles.
This fact accounts for the variation from 20 to 40 feet in the values in column 4 for the various classes of
vehicles.(e) The terms ``GVWR'' and ``GVW'' refer to the manufacturer's gross vehicle weight rating and the actual gross
vehicle weight, respectively. [36 FR 20298, Oct. 20, 1971, as amended at 37 FR 5251, Mar. 11, 1972; 37 FR 11336, June 7, 1972; 67 FR 51777, Aug. 9, 2002]