~.

~
e
The Engineering Society
For Advancing Mobility
~ Land Sea Air and Space®
INTERNATIONA L
SURFACE
VEHICLE
.....
• •W!! J260
REV.
JUN90

400 Commonwealth Drive, Warrendale, PA 15096-0001

RECOMMENDED Issued 1971-09
Revised 1990-06-21
PRACTICE
Submitted for recognition as an American National Standard Superseding J260 JAN80

(R) REAR UNDERRIDE GUARD TEST PROCEDURE

1. SCOPE:
This SAE Recommended Practice is intended to provide a uniform basis for
evaluating the effectiveness of rear underride devices employed to reduce the
likelihood of penetration of the passenger compartment of an impacting
vehicle. The procedures described in this document provide means for
determining the characteristics of a rear underride guard, taking into
consideration the nature and direction of forces involved.
2. DISCUSSION:
The static test procedure outlined in this document was established after a
detailed study which included field observations of typical rear-end
collisions involving heavier vehicles being impacted by lighter passenger
vehicles. These observations, as well as analysis of typical accidents,
indicated that the underride guard is essentially an occupant rather than a
vehicle protection device. It was also recognized that in establishing the
characteristics of an underride guard and the test procedures to evaluate it,
due consideration had to be given to establishing a realistic balance between
providing protection for the major portion of vehicles operating on United
States highways and avoiding undue restriction on the mobility and operating
characteristics of vehicles equipped with underride devices. Taking these
factors into consideration, it was concluded that the development of uniform
procedures for evaluating the characteristics of underride guards would be of
assistance in the design and engineering of these types of devices and would
provide a basis for comparative tests of the devices at various facilities.
It was also recognized, however, that evaluation procedures involving
full-scale components and vehicles in dynamic situations, although most
representative of actual impacts, had serious limitations.

SAE Technical Board Rules provide that: "This report is published by SAE to advance the state of technical and engineering sciences.
The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement

o arising therefrom, is the sole responsibility of the user."

rS. A. E
SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your
written comments and suggestions. e

Copyright 1990 Society of Automotive Engineers, Inc.

All rights reserved. Printed in U.S.A

LI
 SAE J260 Revision JUN90

2. (Conti nued):
Thus, few laboratory facilities are available that can readily conduct this
type of evaluation, and the establishment of adequate facilities will involve
cost outlays beyond the means of many laboratories. Additionally, the
limited production of specialized vehicles, which might be equipped with
underride guards, would mean destructive testing of an unduly high percentage
of the production run. Finally, the varying nature of the configuration and
size of passenger vehicles which may impact rear underride guards, as well as
the direction and velocity at which the barriers are impacted, further
complicates the establishment of uniform full-scale evaluation· procedures.
For these reasons, it was decided to present a test procedure for static
testing of vehicle components.
3. STATIC TEST:
3.1 Test Equipment:
3.1.1 General: The static test is conducted with equipment suitable for
applying and measuring the required loads and deflections.
3.1.2 Loading Plate: The test load is applied to the guard through a 12 x 12 in
(305 x 305 mm) steel plate of sufficient thickness to preclude
deformation. The width of this plate approximates the width of a typical
6-cyl engine block, and represents a concentrated load application.
3.1.3 Instrumentation: Provision shall be made for measuring applied load and
longitudinal displacement of the loading plate.
3.2 Test Procedure:
3.2.1 Installation: The guard shall be attached to a complete frame, the
affected portions of the body and chassis frame, or frame alone. The
vehicle, or portion thereof, being tested shall be rigidly supported in a
manner that will not restrict deformation of the guard and affect parts of
the chassis frame and body. All components which may affect load or
deflection shall be installed.
3.2.2 Test Zone: With the vehicle at curb weight, the test zone is determined
as follows (Figure 1):
a. This zone is bounded by horizontal planes at 66 in (1680 mm) above
ground level and at 18 in (455 mm) above ground level.
b. The rearmost boundary of the zone is a lateral, vertical plane
containing that chassis, body or component point, excluding the
underride guard and its horizont~l supports, that is between 18 in
(455 mm) and 66 in (1680 mm) above ground level and is rearmost on the
vehicle. The forward boundary of this zone is a lateral, vertical
plane 25 in (635 mm) forward of the rearmost boundary.
f~
;
'"00,-_. _ I
- 2 -
 SAE 'J260 Revision JUN90

3.2.2 (Continued):
c. The lateral boundaries are determined by longitudinal, vertical planes
containing the points on each side of the vehicle that have the
greatest lateral positions at or within the above vertical and
longitudinal boundaries, exclusive of flexible fender extensions and
mud flaps.

12 LOAD 12
(~I APPLICATION (JO~I
UN(

FIGURE 1 - Underride Guard Test Zone

3.2.3 Load Application: The underride guard shall be tested by applying the ...
test load through the loading plate in the direction of vehicle forward
horizontal travel at locations defined below.
The test load shall be applied to the underride guard with the center of
the loading plate at any location between two points 12 in (305 mm) .
inboard from each of the two lateral boundaries. At least one test load
cycle shall be conducted with t~e loading plate located at that point
across the load application line reasonably expectable by documented
engineering inspection to yield either the greatest deformation for a
given load or the least load to produce a given deformation. During these
load applications, the center of the loading plate shall be 16 + 1, -0 in
(406 + 25, -0 mm) from ground level on a vehicle at curb weight. It is
not required that a guard loaded at one point be able to withstand
subsequent loading at a second point.
3.2.4 The loading rate shall not exceed 10 in/s (254 mm/s). The time of load
application shall not exceed 2 min.
3.2.5 The vehicle or portion thereof to be tested may be oriented to facilitate
testing, but the relative orientation of loading plate and vehicle as
prescribed above shall be maintained. The loading plate placement is
spe~ified to assure distribution of the load over a reasonable area
without gaining load-carrying ability from vehicle components too high to
contribute to underride protection.

- 3 -
 SAE ,J260 Revision JUN90

3.2.6 Test Termination: The test may be terminated when the desired load or
deflection is reached, and must be terminated if the underride guard
. deforms to allow the loading plate to reach the forward boundary limit
25 in (635 mm) forward of the rearmost boundary.
3.3 Test Measurements:
3.3.1 The following measurements shall be recorded:
a. Load applied to the loading plate.
b. Loading plate displacement.

The (R) is for the convenience of the user in locating areas where technical
revisions have been made to the previous issue of the report. If the symbol is
0'
next to the report title, it indicates a complete revision of the report.

- 4 -
 J260 JUN90
RATIONALE:
Not applicable.
RELATIONSHIP OF SAE STANDARD TO ISO STANDARD:
Not applicable.
APPLICATION:
This SAE Recommended Practice is intended to provide a uniform basis for
evaluating the effectiveness of rear underride devices employed to reduce the
likelihood of penetration of the passenger compartment of an impacting vehicle.
The procedures described in this document provide means for determining the
characteristics of a rear underride guard, taking into consideration the nature
and direction of forces involved.
REFERENCES:
Not applicable.
COMMITTEE COMPOSITION:
DEVELOPED BY THE SAE IMPACT AND ROLLOVER TEST PROCEDURE STANDARDS COMMITTEE:
A. H. Thebert, Engineering Research Analysis, Utica, MI - Chairman
c' S.
C.
R.
H. Backaitis, Dept. of Transportation, Hashington, DC
J. Griswold, Jr., C. J. Griswold Inc. Consulting Engrg., Bloomfield Hills, MI
H. Hultman, Ford Motor Co., Dearborn, MI
J. Jensen, Jr., General Motors Corp., Milford, MI
M. E. Klima, Toyota Motor Sales USA, Torrance, CA
E. C. Menne, Navistar Intl. Trans. Corp., Ft. Hayne, IN
H. J. Mertz, GMC, Harren, MI
K. F. Orlowski, Troy, MI
T. Raabis, Mercedes Benz AG, Montvale,. NJ
J. C. Stultz, Transportation Res. Ctr. of Ohio, E. Liberty, OH
T. M. Thomas, Failure Analysis Assocs., Phoenix, AZ

c
 o

This report is published by SAE to advance the state of technical and

engineenng sCiences. The use ofthis report IS entirety voluntary. and its
o
applicability and suitability for any particular use. including any patent
infringement arising therefrom. IS the sole responSibility of the user.
PRINTED IN U.S.A.