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U. S. DEPARTMENT OF LABOR
JAMES J. DAVIS, Secretary

BUREAU OF LABOR STATISTICS
ETHELBERT STEWART, Commissioner

B U LLE TIN O F TH E U N IT E D ST A T E S 1
B U R E A U O F L A B O R S T A T I S T I C S / ...................
S A F E T Y

CODE

N 350
o.

SERIES

S E IF A IO SO L B R T R T S SF R
P C IC T N F A O A O Y ET O
A P O A O E E T IC H A L H IN
P R V L F L C R E D IG T G
DVC SF RMT RV HCE
E I E O OO E I L S




ILLUMINATING ENGINEERING SOCIETY
NEW YORK, N. Y ., SPONSOR

TENTATIVE AMERICAN STANDARD
Approved November 11, 1922, by
American Engineering Standards Committee

JANUARY, 1924

WASHINGTON
GOVERNMENT PRINTING OFFICE
1924




ADDITIONAL COPIES
OF THIS PUBLICATION M A Y BE PROCURED FROM
THE SUPERINTENDENT OF DOCUMENTS
GOVERNMENT PRINTING OFFICE
W ASHINGTON, D.' C.
AT

5 CENTS PER COPY

PREFACE,

IN T E R IM R E P O R T O F C O M M IT T E E O N M O T O R V E H IC L E L IG H T IN G .

The first specifications for tests o f headlighting devices for ap­
proval by State' authorities were put forth by this committee in 1918.
These were admittedly o f a very lenient and tentative character. On
account o f the meager amount o f laboratory data and o f practical
experience on the road which were available at that time, it was
necessary that the specifications should not be made too hard and
fast, but that they should be drawn with a view to future improve­
ment as experience might show necessary. Accordingly a further
revision was effected in 1919, and a revised edition o f the rules was
put out under date o f May, 1920. This revision showed marked im­
provements in the specifications, and was adopted by a considerable
number o f States.
Since that time further experience has accumulated in this field,
particularly as a result of the adoption by the State o f Massachu­
setts o f specifications for laboratory tests which in 'some respects
went further than those o f the Illuminating Engineering Society
committee, and the application o f which was attended with good
results. It became clear from the situation that the Illuminating
Engineering Society specifications required further improvement,
and that the data upon which such improvement could be based had
become available as a result o f a large number o f tests made for
various States, the results o f which tests had become matters o f public
record. The committee on motor vehicle lighting has therefore gone
over its specifications very thoroughly and presents herewith a re­
vised edition o f them.
It should be specifically pointed out that these revised rules pre­
scribe tests which can be made only in a photometric laboratory
equipped with precise measuring instruments and photometric stand­
ards. These rules for laboratory testing are much too complicated
to be applied to tests o f headlights on the road, and are not intended
so to be applied. The present amplification o f the acceptance test
is a natural result o f the development o f the art and is designed as
a more complete method o f excluding inferior devices.
In putting forth this revision it is not the intent o f the com­
mittee that headlighting devices which have passed tests under the
older specifications and have been approved ought necessarily to be
79991°— 24




III

IV

PREFACE.

removed summarily from approval lists. The committee, without
o f course having any jurisdiction in the matter, respectfully submits
that in fairness to all a time interval should be allowed and an­
nounced, at the expiration of which all devices which do not comply
with the revised specifications should no longer be permitted to be
used.




COMMITTEE ON MOTOR VEHICLE LIGHTING 1921-1922.
F. C.

C aldw ell.

G . N . C h a m b e r l a in .
P . W . C obb.

E. C . C r i t t e n d e n .
A. W . D e v i n e .
J. A. H o e v e l e r .
W. F. L i t t l e .




W. A. M c K a y .
A. L. M c M u r t r y .
H. H . M a g d s i c k .
L. C. P o r te r .
C. H. S h a r p , Chairman.
G. H. S t i c k n e y .
L. E. V o y e r .
V




CONTENTS.
Page.

Definition-----------------------------(A ) Tests o f devices used in pairs-----------------------------------------------------Samples fo r test__________________________________________________
Reflectors and incandescent lamps_______________________________
Marks o f identification__________________________________________
Adjustm ent o f devices-----------------------------------------------------------------Focal adjustments o f incandescent lamps_______________________
Photom etric tests--------------------------------------------------------------------------Distribution o f samples__________________________________________
Diagram o f test positions________________________________________
(B ) Tests o f devices used singly____________________________________
R e p o r ts_________________ ._________________________________________




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BULLETIN OF THE

U. S. BUREAU OF LABOR STATISTICS.
WASHINGTON

NO. 350

Ja n u a r y , » 2 4

SPECIFICATIONS OF LABORATORY TESTS FOR APPROVAL OF
ELECTRIC HEADLIGHTING DEVICES FOR MOTOR VEHICLES.
D E F IN IT IO N .

By headlighting device is meant either the integral and complete
headlamp or a device intended to modify in a suitable manner the
beam o f the ordinary type of headlighting equipment.
(A) TESTS OF DEVICES USED IN PAIRS.

Samples for test.
The samples submitted to the testing authority shall be representa­
tive o f the device as manufactured and as marketed. They shall be
accompanied by printed instructions for their use as issued by the
manufacturer o f the device. The samples submitted shall include
as, much o f the accessory equipment peculiar to the device (except
batteries) as is necessary to operate the device in its normal man­
ner. In the case o f front glasses, the samples shall be one pair each
o f 83% (or Ford size), 8 J, 9, and
inch diameter when practicable.

Reflectors and incandescent lamps.

In the case o f devices to be used in connection with standard para­
bolic reflectors, the reflectors used in making the laboratory tests
shall be o f standard high-grade manufacture, o f 1.25-inch focal
length, with clean and highly polished surfaces, and as nearly truly
paraboloidal in form as practicable, and as approved for this purpose
by the National Bureau o f Standards.
The incandescent lamps used in connection with the laboratory
test shall be o f standard manufacture and as approved for this pur­
pose by the National Bureau of Standards. In the case o f devices
involving the use o f special incandescent lamps, such lamps, together
with any necessary accessories, shall be submitted.

Marks of identification.
Each device submitted must bear a distinctive designation promi­
nently and permanently indicating the name and type o f the device.
Special incandescent lamps submitted in connection with devices
shall bear the manufacturer’s normal clear-bulb rating.




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HEADLIGHTTNG DEVICES FOR MOTOR VEHICLES.

Adjustment of devices.
The testing authority shall adjust the device in accordance with
the printed instructions issued by the manufacturer, which instruc­
tions must be adequate for practical purposes. A n exact description
o f the adjustment made for test shall be given in the report.

Focal adjustments of incandescent lamps.

The following designations o f the focal adjustments o f the
incandescent lamp in the parabolic reflector are adopted:
Principal Focus. The beam, with bare reflector or plain front
glass, is nearly parallel and o f the smallest possible diameter.
Rear Focus. The beam, with bare reflector or plain front
glass diverges as much as possible without having a dark center.
Front Focus. The beam, with bare reflector or plain front
glass, converges and crosses near the lamp and then diverges
as much as possible without having a dark center.
Special Focus. A special focal adjustment is allowed only
when it can be clearly defined and described.

Photometric tests.

The tests shall be as follow s:
TEST 1.

A pair o f testing reflectors, mounted similarly to the headlamps
on a car, shall be set up in a dark room at a distance o f not less
than 60 feet nor more than 100 feet from a vertical white screen.
I f a testing distance o f 100 feet is taken, the reflectors shall be
set 28 inches apart from center to center, and if a shorter testing
distance is taken the distance between reflectors shall be propor­
tionately reduced. The axes of the lamps shall be parallel and
horizontal, or tilted in a vertical plane in accordance with manu­
facturer’s adjustment. The intensity o f the combined light shall
then be measured with each pair o f samples in turn, with the
reflectors fitted with a pair of incandescent lamps of the gas-filled
type, 6 -8 volts, 21 scp. rating. The lamps shall be such as will
give their rated candlepower when operated at their rated efficiency.
They shall be operated at their rated candlepower.
Measurements shall be made at the following points at the surface
o f the screen:
A. In the median vertical plane parallel to the lamp axes, on
a level with the lamps.
B. In the median plane one degree o f arc below the level of the
lamps.
C. In the median plane one degree of arc above the level o f the
lamps.




HEADLIGHTING DEVICES FOR MOTOR VEHICLES.

3

D.
Four degrees of arc to the left of the median plane and one
degree o f arc above the level of the lamps.
P L and PR. One and one-half degrees o f arc below the level of the
lamps and three degrees o f arc to the left and to the right, respec­
tively, of the median plane.
QL and QR. Three degrees o f arc below the level o f the lamps and
six degrees o f arc to the left and to the right, respectively, o f the
median plane.
A diagram o f test positions is shown in Fig. 1.
A ll pairs o f samples tested under the conditions prescribed above
shall conform to the following specifications for observed apparent
candlepower:
Point A, not less than 1,800 candlepower nor more than 6,000 can­
dlepower.
Point B, not less than 7,200 candlepower, and there shall not be
less than 7,200 candlepower at any point on the horizontal line
through B, one degree to the left and to the right o f B.
Point O, not over 2,400 candlepower, and not less than 800 candlepower.
Point D, not over 800 candlepower.
Points P L and PR, at each o f these points and at every point on
the line between them, not less than 5,000 candlepower.
Points QL and QR, at each o f these points and at every point on
the line between them, not less than 2,000 candlepower.
N o t e .— The above testing directions are drawn specifically to cover
the case o f devices accessory to parabolic reflectors o f 1£ inch focal
length. In the case o f other classes o f devices where these directions
evidently can not be applied literally, their intent must be adhered
to and the testing positions and candlepower limitations shall govern
in all cases.
TEST 2.

A single pair o f samples taken as an average representative of
the device as manufactured shall be submitted to a complete test
with the same testing equipment as specified for Test 1. This test
shall show the light distribution characteristics by actual measure­
ments made in accordance with the best laboratory practice.

Distribution of samples.
One pair o f the samples submitted shall be retained at the testing
laboratory for the purpose of future reference and as samples o f
construction.




0

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DEGREES SPREAD

I.E.S. 1S20 LIMITS.

f.E S. 1922 LIMITS.

A-B

4800 cp Min.

A

1800 pp Min. 6000 Max.

C
D

2400 cp Max.

B

800 cp Min.

C

1° Right & Left 7200 Min;
' 800 cp Min. 2400 Max.

E -F

1200 cp Min.




D
P L to PR
Q Lto Q R
Fig. i.—Diagram of Test Positions.

800'Max.
5000 Min.
2000 Min.

HEADLIGHTING DEVICES FOR MOTOR VEHICLES.

1

H E ADLJ.GHTING DEVICES FOR MOTOR V EH ICLES.

5

(B ) TESTS OE DEVICES USED SINGLY.

Motor-cycle headlamps are used singly, and not in pairs, and have
commonly a reflector o f smaller diameter and shorter focal length.
Hence devices for use in connection with them are not included in the
same classification as those for other motor vehicles. For the labora­
tory tests o f such devices two samples o f representative sizes shall be
submitted. They shall be tested with representative motor-cycle
headlamp reflectors. The numerical limitations of apparent candlepower for Test 1 with one lamp only shall be as follow s:
Point A , not less than 1,800 candlepower.
Point B, not less than 3,600 candlepower, and there shall not be
less than 3,600 candlepower at any point on the horizontal line
through B, one degree to the left and to the right o f B.
Point C, not more than 2,400 candlepower.
Point D, not more than 800 candlepower.
Points P L and PR, at each of these points and at every point on
the line between them, not less than 2,500 candlepower.
Points QL and QR, at each of these points and at every point on
the line between them not less than 1,000 candlepower.
Test 2 shall be made with one lamp, and not with two.
Other deviations from the details o f procedure are obviously made
necessary because of the fact that single devices instead o f pairs are
subjects o f test.

Reports.
The report o f the test shall be rendered in duplicate to the State
authority, and shall be signed or initialed not only by the expert
making the test, but also by an executive officer o f the institution
making the test.







IN D EX.
Page.

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Adjustment o f devices-------------------------------Adjustments, focal, o f incandescent lamps
Definition o f headlighting device---------------Devices, adjustment o f-----------------------------tests of, used in pairs___________
tests of, used singly----------------------Distribution o f samples__________________
Identification, marks o f-------------------------------Incandescent lamps------------------------------------focal adjustments of__
Marks o f identification___________________
Photometric te s ts --------------------------------------Reflectors___________________________________
Reports____________________________________ ..
Samples, distribution o f __________________
for test --------------------------------------Test 1 _____________________________________

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Tests o f devices used in pairs---------------o f devices used singly______________
p h otom etric------------------------------------Test positions, diagram o f________________

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