WAIS Document Retrieval[Code of Federal Regulations]

[Title 49, Volume 5, Parts 400 to 999]

[Revised as of October 1, 1999]

From the U.S. Government Printing Office via GPO Access

[CITE: 49CFR571.223]

[Page 639-644]

TITLE 49--TRANSPORTATION

CHAPTER V--NATIONAL HIGHWAY TRAFFIC

SAFETY ADMINISTRATION, DEPARTMENT

OF TRANSPORTATION

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS--Table of Contents

Subpart B--Federal Motor Vehicle Safety Standards

Sec. 571.223 Standard No. 223; Rear impact guards.

S1. Scope. This standard specifies requirements for rear impact

guards for trailers and semitrailers.

S2. Purpose. The purpose of this standard is to reduce the number of

deaths and serious injuries that occur when light duty vehicles collide

with

[[Page 640]]

the rear end of trailers and semitrailers.

S3. Application. This standard applies to rear impact guards for

trailers and semitrailers subject to Federal Motor Safety Standard No.

224, Rear Impact Protection (Sec. 571.224).

S4. Definitions.

In this standard, directional terms such as bottom, center, height,

horizontal, longitudinal, transverse, and rear refer to directions

relative to the vehicle orientation when the guard is oriented as if it

were installed on a vehicle according to the installation instructions

in S5.5 of this section.

Chassis means the load supporting frame structure of a motor

vehicle.

Guard width means the maximum horizontal guard dimension that is

perpendicular to the longitudinal vertical plane passing through the

longitudinal centerline of the vehicle when the guard is installed on

the vehicle according to the installation instructions in S5.5 of this

section.

Horizontal member means the structural member of the guard that

meets the configuration requirements of S5.1.1 through 5.1.3 of

Sec. 571.224, Rear Impact Protection, when the guard is installed on a

vehicle according to the guard manufacturer's installation instructions.

Hydraulic guard means a guard designed to use fluid properties to

provide resistance force to deformation.

Rear impact guard means a device installed on or near the rear of a

vehicle so that when the vehicle is struck from the rear, the device

limits the distance that the striking vehicle's front end slides under

the rear end of the impacted vehicle.

Rigid test fixture means a supporting structure on which a rear

impact guard can be mounted in the same manner it is mounted to a

vehicle. The rigid test fixture is designed to resist the forces applied

to the rear impact guard without significant deformation, such that a

performance requirement of this standard must be met no matter how small

an amount of energy is absorbed by the rigid test fixture.

S5. Requirements.

S5.1 Projected Vertical Height. The horizontal member of each

guard, when viewed from the rear as it would be installed on a trailer

pursuant to the installation instructions or procedures required by S5.5

of this standard, shall have a vertical height of at least 100 mm at

each point across the guard width, when projected horizontally on a

transverse vertical plane. Those installation instructions or procedures

shall specify that the guard is to be mounted so that all portions of

the horizontal member necessary to achieve a 100 mm high projected

vertical height are located not more than 305 mm forward of the

vehicle's rear extremity, as defined in S4 of 49 CFR 571.224, Rear

Impact Protection. See Figure 1 of this section.

S5.2 Strength and Energy Absorption. When tested under the

procedures of S6 of this section, each guard shall comply with the

strength requirements of S5.2.1 of this section at each test location

and the energy absorption requirements of S5.2.2 of this section at test

location P3, as specified in S6.4 of this section. However, a particular

guard (i.e., test specimen) need not be tested at more than one

location.

S5.2.1 Guard Strength. The guard must resist the force levels

specified in S5.2.1 (a) through (c) of this section without deflecting

by more than 125 mm.

(a) A force of 50,000 N at test location P1 on either the left or

the right side of the guard as defined in S6.4(a) of this section.

(b) A force of 50,000 N at test location P2 as defined in S6.4(b) of

this section.

the right side of the guard as defined in S6.4(c) of this section.

S5.2.2 Guard Energy Absorption. A guard, other than a hydraulic

guard, shall absorb by plastic deformation within the first 125 mm of

deflection at least 5,650 J of energy at each test location P3. See

Figure 2 of this section.

S5.3 Labeling. Each guard shall be permanently labeled with the

information specified in S5.3 (a) through (c) of this section. The

information shall be in English and in letters that are at least 2.5 mm

high. The label shall be placed on the forward-facing surface of the

horizontal member of the guard, 305 mm inboard of the right end of the

guard.

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(a) The guard manufacturer's name and address.

(b) The statement: ``Manufactured in ________'' (inserting the month

and year of guard manufacture).

manufacturer that the guard conforms to all requirements of this

standard.

S5.4 Guard Attachment Hardware. Each guard, other than a guard that

is to be installed on a vehicle manufactured by the manufacturer of the

guard, shall be accompanied by all attachment hardware necessary for

installation of the guard on the chassis of the motor vehicle for which

it is intended.

S5.5 Installation Instructions. The manufacturer of rear impact

guards for sale to vehicle manufacturers shall include with each guard

printed instructions in English for installing the guard, as well as a

diagram or schematic depicting proper guard installation. The

manufacturer of a rear impact guard for one of its own vehicles shall

prepare and keep a copy of installation procedures applicable to each

vehicle/guard combination for a period of one year from the date of

vehicle manufacture and provide them to NHTSA on request. The

instructions or procedures shall specify:

(a) Vehicles on which the guard can be installed. Vehicles may be

designated by listing the make and model of the vehicles for which the

guard is suitable, or by specifying the design elements that would make

any vehicle an appropriate host for the particular guard (e.g., vehicles

with frame rails of certain spacing and gauge of steel).

(b) A description of the chassis surface to which the guard will be

attached, including frame design types with dimensions, material

thickness, and tire track width. This description shall be detailed

enough to permit the agency to locate and duplicate the chassis surface

during compliance testing.

chassis of each vehicle make and model listed or to the design elements

specified in the instructions or procedures. The principal aspects of

vehicle chassis configuration that are necessary to the proper

functioning of the guard shall be specified. If the chassis strength is

inadequate for the guard design, the instructions or procedures shall

specify methods for adequately reinforcing the vehicle chassis.

Procedures for properly installing any guard attachment hardware shall

be provided.

S6. Guard Test Procedures. The procedures for determining compliance

with S5.2 of this section are specified in S6.1 through S6.6 of this

section.

S6.1 Preparation of Hydraulic Guards. For hydraulic guards, the

horizontal member of the guard is deflected in a forward direction until

the hydraulic unit(s) have reached the full extent of their designed

travel or 610 mm, whichever occurs first. The hydraulic units are

compressed before the application of force to the guard in accordance

with S6.6 of this section and maintained in this condition throughout

the testing under S6.6 of this section.

S6.2 Guard Installation for Strength and Energy Absorption Tests.

(a) The rear impact guard is attached to a test device.

(b) The test device for the compliance test will be whichever of the

following devices, if either was used, the manufacturer used as a basis

for its certification of the guard in S5.3(c) of this section. If the

manufacturer did not use one of these devices or does not specify a

device when asked by the agency, the agency may choose either of the

following devices--

(1) A rigid test fixture. In the case of testing on a rigid test

fixture NHTSA will consult the installation instructions or procedures

to determine the surface or structure that the guard is supposed to be

mounted to and mount it to the rigid test fixture in the same way.

(2) A complete trailer for which installation of the guard is

suitable, as provided in the manufacturer's installation instructions or

procedures required by S5.5 of this section. The trailer chassis is

secured so that it behaves essentially as a fixed object during the

test, such that the test must be passed no matter how little it moves

during the test.

procedures for guard attachment provided

[[Page 642]]

by the guard manufacturer for that guard as required by S5.5 of this

section.

S6.3 Force Application Device. The force application device employed

in S6.6 of this section consists of a rectangular solid made of rigid

steel. The steel solid is 203 mm in height, 203 mm in width, and 25 mm

in thickness. The 203 mm by 203 mm face of the block is used as the

contact surface for application of the forces specified in S5.2.1 (a)

through (c) of this section. Each edge of the contact surface of the

block has a radius of curvature of 5 mm plus or minus 1 mm.

S6.4 Test Locations. With the guard mounted to the rigid test

fixture or to a complete trailer, determine the test locations P1, P2,

and P3 in accordance with the procedure set forth in S6.4 (a) through

(a) Test location P1 is the point on the rearmost surface of the

horizontal member of the guard that:

(1) Is located at a distance of \3/8\ of the guard width from the

vertical longitudinal plane passing through center of the guard;

(2) Lies on either side of the center of the guard's horizontal

member; and

(3) Is 50 mm above the bottom of the guard.

(b) Test location P2 is the point on the rearmost surface of the

horizontal member of the guard that:

(1) Lies in the longitudinal vertical plane passing through the

center of the guard's horizontal member; and

(2) Is 50 mm above the bottom of the guard.

horizontal member of the guard that:

(1) Is not less than 355 mm and not more than 635 mm from the

vertical longitudinal plane passing through center of the guard;

(2) Lies on either the right or left side of the horizontal member

of the guard; and

(3) Is 50 mm above the bottom of the guard.

S6.5 Positioning of Force Application Device. Before applying any

force to the guard, locate the force application device such that:

(a) The center point of the contact surface of the force application

device is aligned with and touching the guard test location, as defined

by the specifications of S6.4 of this section.

(b) The longitudinal axis of the force application device passes

through the test location and is perpendicular to the transverse

vertical plane that is tangent to the rearmost surface of the guard's

horizontal member.

S6.6 Force Application. After the force application device has been

positioned according to S6.5 of this section, apply the loads specified

in S5.2.1 of this section. Load application procedures are specified in

the S6.6 (a) through (d) of this section.

(a) Using the force application device, apply force to the guard in

a forward direction such that the displacement rate of the force

application device is the rate, plus or minus 10 percent, designated by

the guard manufacturer within the range of 2.0 cm per minute to 9.0 cm

per minute. If the guard manufacturer does not designate a rate, any

rate within that range may be chosen.

(b) If conducting a strength test to satisfy the requirement of

S5.2.1 of this section, the force is applied until the forces specified

in S5.2.1 of this section have been exceeded, or until the displacement

of the force application device has reached at least 125 mm, whichever

occurs first.

absorption levels to satisfy the requirement of S5.2.2 of this section,

apply the force to the guard until displacement of the force application

device has reached 125 mm. For calculation of guard energy absorption,

the value of force is recorded at least ten times per 25 mm of

displacement of the contact surface of the loading device. Reduce the

force until the guard no longer offers resistance to the force

application device. Produce a force vs. deflection diagram of the type

shown in Figure 2 of this section using this information. Determine the

energy absorbed by the guard by calculating the shaded area bounded by

the curve in the force vs. deflection diagram and the abscissa (X-axis).

(d) During each force application, the force application device is

guided so

[[Page 643]]

that it does not rotate. At all times during the application of force,

the location of the longitudinal axis of the force application device

remains constant.

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[[Page 644]]

[GRAPHIC] [TIFF OMITTED] TC01AU91.146

[61 FR 2030, Jan. 24, 1996, as amended at 63 FR 3662, Jan. 26, 1998]