Full text of Safety Code for Mechanical Power-Transmission Apparatus : Bulletin of the United States Bureau of Labor Statistics, No. 364

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

BUREAU OF LABOR STATISTICS
ETHELBERT STEWART, Commissioner

B U L L E T IN O F T H E U N IT E D S T A T E S )
BUREAU OF LAB O R S T A T IS T IC S ) • • • •
SAFETY

CODE

No. 364

SERIES

SAFETY CODE FOR MECHANICAL
POWER-TRANSMISSION APPARATUS
NATIONAL BUREAU OF CASUALTY AND SURETY UNDERWRITERS
INTERNATIONAL ASSOCIATION OF INDUSTRIAL ACCIDENT BOARDS AND COMMISSIONS

THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS
SPONSORS

TENTATIVE AMERICAN STANDARD
Approved July, 1923, by
American Engineering Standards Committee

AUGUST, 1924

WASHINGTON
GOVERNMENT PRINTING OFFICE
1924

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

10 CENTS P E R C O P Y

SECTIONAL COMMITTEE WHICH DEVELOPED THE SAFETY CODE FOR
MECHANICAL POWER-TRANSMISSION APPARATUS.
Carl

A uel,

Chairman.

T homas

N ia l ,

Secretary.

Carl B. Auel, Manager Employees’ Service Departments, Westinghouse Elec
tric and Manufacturing Co., East Pittsburgh, Pa., representing The American
Society of Mechanical Engineers.
F.
M. Bullen, United States Casualty Co., 80 Maiden Lane, New York, N. Y.,
representing the National Bureau of Casualty and Surety Underwriters.
Lucian W . Chaney, Bureau of Labor Statistics, United States Department of
Labor, Washington, D. C., representing the International Association o f In
dustrial Accident Boards and Commissions.
Clifford B. Connelly, Commissioner Department of Labor and Industry, Com
monwealth of Pennsylvania, Harrisburg, Pa., representing the International
Association of Industrial Accident Boards and Commissions.
John A. Dickinson, Bureau of Standards, Washington, D. C., representing the
Bureau of Standards.
Paul Douley, 719 Fifteenth Street SE., Washington, D. C., representing the
International Association of Machinists.
L. L. Hall, National Council on Workmen’s Compensation, 16 E ast Fortieth
Street, New York, N. Y.
Francis A. Hobart, 27 Morton Avenue,. Newport, R. I., representing the In
ternational Association o f Machinists.
Holger Jensen, Manager Engineering Department, Maryland Casualty Co.,
Baltimore, Md., representing the National Bureau of Casualty and Surety
Underwriters.
Arthur C. Jewett, Personnel Superintendent Winchester Repeating Arms
Co., New Haven, Conn., representing The American Society o f Mechanical
Engineers.
Robert M. Keown, Industrial Accident Commission, State Capitol, Madison,
W is., representing the International Association of Industrial Accident Boards
and Commissions.
Rowland H . Leveridge, Bureau of Electrical and Mechanical Equipment,
New Jersey Department of Labor, Trenton, N. J., representing the International
Association of Industrial Accident Boards and Commissions.
John P. Meade, Director Division of Industrial Safety, Department o f Labor
and Industries, State House, Boston, Mass., representing the International
Association o f Industrial Accident Boards and Commissions.
Frank L . Morse, President Morse Chain Co., Ithaca, N. Y ., representing The
American Society o f Mechanical Engineers.
George M. Naylor, Vice President The Fairbanks Co., 416 Broome Street,
New York, N. Y ., representing The American Society of Mechanical Engineers.
Thomas M. Nial, Assistant Secretary National Bureau of Casualty and
Surety Underwriters, 120 W est Forty-second Street, New York, N. Y., repre
senting the National Bureau of Casualty and Surety Underwriters.
W alter S. Paine, Research Engineer Bureau of Inspection and Accident
Prevention, Aetna Life Insurance Co., 650 Main Street, Hartford, Conn.,
representing the National Bureau of Casualty and Surety Underwriters.
Charles H . Savage, 235 Ninth Street NE., Washington, D . C., representing
the International Association o f Machinists.
H . A . Schultz, United States Steel Corporation, 71 Broadway, New York,
N. Y ., representing the National Safety Council.
R. W . Sellew, Consulting Engineer, P. O. Box 467, Middletown, Conn., repre
senting The American Society of Mechanical Engineers.
H . E. Somes, Secretary Chevrolet Motor Co., Inc., Tarrytown, N. Y ., repre
senting The National Safety Council.
John L. Thompson, Superintendent Engineering and Inspection Division,
The Travelers Insurance Co., Hartford, Conn., representing the National Bureau
of Casualty and Surety Underwriters.

SECTIONAL COMMITTEE

G. N. VanDerhoef (alternate for D. C. W righ t), Dodge Manufacturing Co.,
29 W est Broadway, New York, N. Y., representing The American Society of
Mechanical Engineers.
H. G. Wiberg, Chief Engineer and Underwriter Lumber Mutual Casualty
Co., 41 East' Forty-second Street, New York, N. Y., representing National
Association of Mutual Casualty Cos.
E. D. Wilson, 53 Pinebrook Drive, Larchmont, N. Y., representing The
American Society of Mechanical Engineers.
Donald C. Wright, Works Manager Ames Iron Works, Oswego, N. Y., repre
senting The American Society of Mechanical Engineers.

CONTENTS,

IN TRO DU CTIO N.

Page

Scop©___________________________________________________________________ i-----------Interpretations and exceptions------------------------------------------------------------------------New and existing installations________________________________________________
Mandatory and advisory requirements______________________________________
Definitions---------------------------------------------------------------------------------------------------------P abt

I.— PR IM E MOVERS.

Section 10. Prime-mover guards--------------------------------------------------------------------Rule 100. Flyw heels______________________________________________________
Rule 101. Cranks and connecting rods__________________________________
Rule 102. Tail rods or extension piston rods.----------------------------------------Rule 103. Governor balls-------------------------------------------------------------------------P art

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II.— M E C H A N IC AL P O W E R -T R A N S M IS S IO N
EQ UIPM EN T.

Section 20. Shafting________________ *_-----------------------------------------------------------Rule 200. Installation____________________________________________________
Rule 201. Guarding horizontal shafting-----------------------------------------------Rule 202. Guarding vertical and inclined shafting___________________
Rule 203. Projecting ends-----------------------------------------------------------------------Rule 204. Shafting located in basements, etc--------------------------------------Section 21. Pulleys--------------------------------------------------------------------------------------------Rule 210. Guarding----------------------------------------------------------------------------------Rule 211. Location of pulleys-----------------------------------------------------------------Rule 212. Broken pulleys_______________________________________________
Rule 213. Pulley speeds_________________________________________________
Rule 214. Belt guides------------------------------------------------------------------------------Rule 215. Composition and wood pulleys----------------------------------------------Rule 216. Pulleys exposed to corrosion------------------------------------------------Rule 217. Pulleys out of service------------------------------------------------------------Section 22. Belts and ropes-----------------------------------------------------------------------------Rule 220. Horizontal belt, rope, and chain drives______________________
Rule 221. Vertical and inclined belts-----------------------------------------------------Rule 222. Vertical belts---------------------------------------------------------------------------Rule 223. Cone pulley belts--------------------------------------------------------------------Rule 224. Belt tighteners-------------------------------------------------------------------------Rule 225. Guarding overhead rope drives_______________________________
Section 23. Gears, sprockets, and chains-------------------------------------------------------Rule 230. G ea rs__________________________________________________________
Rule 231. Sprockets and chains--------------------------------------------------------------Rule 232. Openings for oiling---------------------------------------------------------------Section 24. Friction drives------------------------ ,---------------------------------------------------Rule 240. Guarding_______________________________________________________
Section 25. Keys, set screws, and other projections-----------------------------------Rule 250. Elimination or guarding---------------------------------------------------------Section 26. Collars and couplings------------------------------------------------------------------Rule 260. C ollars-------------------------------------------------------------------------------------Rule 261. Couplings---------------------------------------------------------------------------------Section 27. Bearings and facilities for oiling--------------------------------------------Rule 270. B earings------------------------------------------------------------------------------—
Rule 271. Ladders------------------------------------------------------------------------------------Rule 272. Oilers, runways, and platforms---------------------------------------------

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CONTENTS.
Part

III.— STARTING AND STOPPING DEVICES.

Page

12
Section 30. Clutches, cut-off couplings, and clutch pulleys________________
Rule 300. Guarding-----------------------------------------------------------------------------------12
Section 31. Belt shifters, shippers, poles, perches, and fasteners_________ 12-14
Rule 310. Belt shifters___________________________________________________
12
Rule 311. Belt shippers and shipper poles______________________________12 ,13
Rule 312. Belt perches-----------------------------------------------------------------------------14
Rule 313. Belt fasteners_________________________________________________
14
P art

IV.— G UARD STA N D AR D S.

Section 40. Standard guards— General requirements______________________
15
Rule 400. Materials_______________________________________________________
15
Rule 401. Design o f guards----------------------------------------------------------------------15
Rule 402. Methods of manufacture-------------------------------------------------------15
16
Section 41. Disk, shield, and “ U ” guards-----------------------------------------------------Rule 410. Disk guards_______ •___________________________________________
16
Rule 411. Shield guards_________________________________________________
16
Rule 412. “ U ” guards___________________________________________________
16
Section 42. Approved materials--------------------------------------------- :-------------------------16-22
Rule 420. Minimum requirements_______________________________________ 1 6 ,1 7
Rule 421. Wood guards---------------------------------------------------------------------------17
Rule 422. Guards for horizontal overhead belts_________________________1 7 -1 9
Rule 423. Guards for horizontal overhead and chain drive-----------------19
Rule 424. Guard rails and toe boards------------------------------------------------------ 19-22
P art

V.— O PERATIN G RU LES.

Section 50. Care o f equipment----------------- t ---------------------------------------------------2 3 ,2 4
Rule 500. G eneral--------------------------------23
Rule 501. Shafting-------------------------------------------------------------------------------------23
Rule 502. B earings-----------------------------------------------------------------------------------23
Rule 503. Hangers-------------------------------------------------------------------------------------23
Rule 504. Pulleys_____________________________________
23
Rule 505. Care of b elts__________________________________________________ 2 3 ,2 4
Rule 506. Belts on overhead pulleys------------------------------------------------------24
Rule 507. Lubrication-------------------------------------------------------------------------------24
Part

VI.—DISCUSSION.

Broken pulleys------------------------------------------------------------------------------------Belt tighteners-------------------------------------------------------------------------------------Power control--------------------------------------------------------------------------------------Power-transmission equipment--------------------------------------------------------------Hand-operated gears------------------------------------------------------------------------------Horizontal overhead belts--------------------------------------------------------------------P art

VII.—REFERENCES.

List of codes approved and published-----------------------------------------------------List of codes in process of development--------------------------------------------------

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BULLETIN OF THE

U. S. BUREAU OF LABOR STATISTICS
W ASHINGTON

NO. 364

AUGUST, 1924

SAFETY CODE FOR MECHANICAL POWERTRANSMISSION APPARATUS.
INTRODUCTION.
SCOPE.

This code applies to all moving parts o f equipment used in the
mechanical transmission o f power, including prime movers, inter
mediate equipment and driven machines, excluding point o f opera
tion.
N ote .— The safeguarding of all connecting rods, cranks, flywheels, shafting,
spindles, pulleys, belts (except flat belts 1 inch or less in width or round belts
one-half inch or less in diameter), link belts, chains, ropes and rope drives,
gears, sprockets, friction drives, cams, couplings, clutches, counterweights,
revolving or reciprocating parts, up to but not including point o f operation, also
all bolts, keys, set screws, oil cups or similar projections, shall be included in
and be in accordance with the provisions o f this safety code for mechanical
power-transmission apparatus.

INTERPRETATIONS AND EXCEPTIONS.

The purpose o f this code is to provide reasonable safety for life,
limb, and health. It is intended to serve as a guide to State and
municipal authorities and may be adopted by them in whole or
in part. This safety code is also in a form to be adopted by indus
trial concerns.
The code should be liberally construed and applied by enforcing
authorities to secure these results; and, in case o f practical difficulty
or unnecessary hardship, exceptions from the literal requirements
may be granted as long as equivalent protection is secured. Where
specific devices or methods are mentioned in this code, other devices
or methods which w ill secure equally good results may be used,
subject to the approval o f the enforcing authority.
NEW AND EXISTING INSTALLATIONS.

A fter the date on which this code becomes effective all new con
struction and installations shall conform to its rules. Equipment
installed prior to that date need not, however, be modified to con
form to its rules unless definite provision is made in the enacting law.
MANDATORY AND ADVISORY REQUIREMENTS.

The word “ shall,” where used, is to be understood as mandatory
and the word “ should ” as advisory.

SAFETY CODE FOR POWER-TRANSMISSION APPARATUS.
D E F IN IT IO N S .

Belt pole.— A 44belt pole,” sometimes called a 44belt shipper ” or
44shipper pole,” is a device used in shifting belts on and on pulleys
on line or countershaft where there are no loose pulleys.
Belt shifter.—A belt shifter is a device for mechanically shifting
belts from tight to loose pulleys or vice versa, or for shifting belts on
cones o f speed pulleys.
Maintenance runway.—44Runway ” shall mean any permanent run
way or platform used fo r oiling, maintenance, running adjustment or
repair work, but not fo r passageway.
Exposed to contact.— The term 44exposed to contact” shall be
interpreted as meaning that the location o f an object is such that a
person is liable to come into contact with it and be injured.
Flywheels.—The term 44flywheel ” is to include flywheels, balance
wheels, and pulleys mounted and revolving on crank shaft o f engine
or other shafting.
Gears.—A set or train o f gears comprises two or more intermesh
ing gears.
Point o f operation.— The term 44point o f operation ” shall be un
derstood to mean that point at which cutting, shaping, or form ing
is accomplished upon the stock and shall include such other points
as may offer a hazard to the operator in inserting or manipulating
the stock in the operation o f the machine.
Prime movers.— The term 44prime movers ” as used in this code is
to include steam, gas, oil, and air engines, motors, steam and hydrau
lic turbines.
Securely fastened .— The term 44securely fastened ” shall mean that
the safety device or object referred to shall be so secured in place
that it can not be moved under normal or reasonably foreseen condi
tions or circumstances.
Sprockets.—A set o f sprockets comprises two or more sprockets
carrying one or more chains.

PART I.— PRIME MOVERS.
SECTION 10. PRIME-MOVER GUARDS.

Rule 100. Flywheels.
Flywheels located so that any part is 6 feet or less above floor or
platform shall be guarded in one o f the follow ing ways:
(а) W ith an inclosure o f sheet, perforated or expanded, metal or
woven wire. F or standards see Part IV , sections 40 and 41.
(б ) W ith guard rails placed not less than 15 inches nor more than
20 inches from rim. When flywheel extends into pit or-is within
12 inches o f floor, a standard toe board shall also be provided. For
standards see Part IV , rule 424.
(c) When the upper rim o f flywheel protrudes through a working
floor, it shall be entirely inclosed or surrounded by guard rail ana
toe board.
(d) F or flywheels with smooth rims 5 feet or less in diameter,
where the* preceding methods can not be applied^ the follow ing may
be used: A disk attached to the flywheel in such manner as to cover
the spokes o f the wheel on the exposed side and present a smooth
surface and edge, at the same time providing means fo r periodic in
spection. A n open space, not exceeding 4 inches in width, may be
left between the outside edge o f the disk and the rim o f the wheel, if
desired, to facilitate turning the wheel over. W here a disk is used,
the keys or other dangerous projections not covered by disk shall be
cut off or covered. (See standard for disk guard Part IV , sec
tion 41.)
N o t e .—

This does not apply to flywheels with solid web centers.

(e) Adjustable guard to be used for starting engine or for running

adjustment may be provided at the flywheel o f gas or oil engines. A
slot opening fo r jack bar w ill be permitted.
Rule 101. Cranks and. connecting rods.
Cranks and connecting rods, when exposed to contact, shall be
guarded in accordance with Part IV , sections 40 and 41, or by a
guard rail as described in Part IV , rule 424.
Rule 103. Tail rods or extension piston rods.
'T ail rods or extension piston rods shall be guarded in accordance
with Part IV , sections 40 and 42, or by a guard rail on sides and
end, with a clearance o f not less than 15 inches when rod is fully
extended.
Rule 103. Governor balls.
Governor balls 6 feet or less from the floor or other working level,
when exposed to contact, shall be provided with an inclosure extend
ing to the top o f the governor balls when at their highest position.
The material used in the construction o f this inclosure shall conform
to Part IV , sections 40 and 42.

---- 2

92111°—24

P A R T II.— MECHANICAL POW ER-TRANSM ISSION EQU IP
MENT.
SECTION 20. SHAFTING.

Rule 200. Installation.
{a) Each continuous line o f shafting shall be secured in position
against excessive endwise movement.
(&) Inclined and vertical shafts, particularly inclined idler shafts,
shall be securely held in position against endwise thrust.
Rule 201. Guarding horizontal shafting.
(a) A ll exposed parts o f horizontal shafting 6 feet or less from
floor or working platform , excepting runways used exclusively for
oiling, or running adjustments, shall be protected by a stationary
casing inclosing shafting completely or by a trough inclosing sides
and top or sides and bottom o f shafting, as location requires.
( b ) Wherever shafting extends over a driveway it should be pro
tected as stated above unless it is located 15 feet or more above
driveway.
(0) Shafting under bench machines shall be inclosed by a sta
tionary casing, or by a trough at sides and top or sides and bottom,
as location requires. The sides o f the trough shall come within at
least 6 inches o f the underside o f table, or i f shafting is located near
floor within 6 inches o f floor. In every case the sides o f trough
shall extend at least 2 inches below or above the shafting as the case
may be.
N o t e .— For requirements regarding materials and construction see Part IV ,
sections 40 and 42.

Buie 202. Guarding vertical and inclined shafting.
Vertical and inclined shafting 6 feet or less from floor or working
platform , excepting maintenance runways, shall be inclosed with a
stationary casing in accordance with requirements o f Part IV , sec
tions 40 and 42.
Buie 203. Projecting shaft ends.
(a)
Projecting shaft ends shall present a smooth edge and end
apd shall not project more than one-half the diameter o f the shaft
unless guarded by nonrotating caps or safety sleeves.
(1) Unused key ways shall be tilled up or covered.
Buie 204. Shafting located in basements, etc.
W hen belts, pulleys, and shafting are located in basements, towers,
and rooms used exclusively for power-transmission equipment, the
requirements for safeguarding may be waived i f the follow ing condi
tions are met:
1.
The basement, tower, or room occupied by transmission equipment shall
be locked against unauthorized entrance.

SAFETY' CODE EOK POWEU-TKAESMiSSlON AIM’AUATUS.

S H A F T IN G LOCATED UNDER BENCH MACHINES

SAFETY CODE FOR POWER-TRANSMISSION APPARATUS.

2. The vertical clearance in passageways between the floor and powertransmission beams, ceiling, or any other objects should not be less than 5
feet 6 inches.
3. The intensity of illumination shall conform to the standard Code for
Lighting of Factories, Mills, and other Work Places.
4. The footing shall be dry, firm, and level.
5. The route followed by the oiler shall be protected in such manner as to
prevent accident.
N ote .— The exemption granted by this rule shall not apply to single isolated
hazards which can be guarded without hardship in the usual prescribed manner.

SECTION 21. PULLEYS.

Rule 210. Guarding.
Pulleys any parts o f which are 6 feet or less from the floor or work
ing platform shall be guarded in accordance with the standards
specified under Part IV , sections 40 and 42. Pulleys serving as bal
ance wheels (e. g., punch presses) on which the point o f contact be
tween belt and pulley is more than 6 feet from the floor or platform
may be guarded with a disk covering the spokes. (See Part IV ,
section 41.)
Rule 211. Location of pulleys.
( a ) Unless the distance to the nearest fixed pulley, clutch, or
hanger exceeds the width of the belt used, a guide shall be provided
to prevent the belt from leaving the pulley on the side where insuf
ficient clearance exists,
( b ) Where there are overhanging pulleys on line, jack, or counter
shafts with no bearing between the pulley and the outer end of the
shaft, a guide to prevent the belt from running off the pulley should
be provided.
( c) For requirements for guarding pulleys located in basements,
towers, and rooms where no employees are regularly stationed, see
Part II, section 20, rule 204.
Rule 212. Broken pulleys.
Pulleys with cracks or pieces broken out of rims shall not be used.
Rule 213. Pulley speeds.
Pulleys operating at rim speed in excess o f 4,000 feet per minute
shall be especially designed for the purpose and carefully balanced
for the speed at which they are to operate.
Rule 214. Belt guides.
Belt guides should not be installed except as provided in rule
211 ( a ) and (&).
Rule 215. Composition and wood pulleys.
Composition or laminated wood pulleys shall not be installed
where they are continually subjected to the action of moisture.
Rule 216. Pulleys exposed to corrosion.
Pulleys used where conditions are such as to produce active cor
rosion should be of corrosion-resisting material.
Rule 217. Pulleys out of service.
Pulleys permanently out of service should not be allowed to re
main on shafting which is in use.

SAFETY CODE FOE POWEB-TRANSMISSION APPARATUS.

SECTION 22. BELT, ROPE, AND CHAIN DRIVES.

Rule 220. Horizontal belts and ropes.
( а ) Where both runs o f horizontal belts are 6 feet or less from the
floor level, the guard shall extend to at least 15 inches above the
belt or to a standard height (see table following rule 420), except that
where both runs o f a horizontal belt are 42 inches or less from the
floor the belt shall be fully inclosed in accordance with Part IV ,
sections 40 and 42.
N ote.— I n power plants or power-development rooms, a guard rail may be
used in lieu o f the above.

(б) Overhead horizontal belts, with lower part 7 feet or less from
the floor or platform, shall be guarded on sides and bottom in ac
cordance with Part IV , section 42, rule 422.
( c) Horizontal overhead belts more than 7 feet above floor or
platform shall be guarded for their entire length under the following
conditions:
1. I f located over passageways or work places and traveling 1,800 feet or
more per minute, and,
2. I f center to center distance between pulleys is 10 feet or more, and,
3. I f belt is 8 inches or more in width.
N ote.— For details of guard construction and for sizes o f material see Part
IV , section 42, rule 422, and table following rule 423, also Discussion, Part VI.

For exception in case of flat belts 1 inch or less in width or round
belts one-half inch or less in diameter, see “ Scope.”
( d ) Where the upper and lower runs o f horizontal belts are so
located that passage of persons between them would be possible, the
passage shall be either:
1. Completely barred by a guard rail or other barrier in accordance with
Part IV, sections 40 and 4 2 ; or
2. Where passage is regarded as necessary there shall be a platform over the
lower run guarded on either side by a railing completely filled in with wire
mesh or other filler, or by a solid barrier.. The upper run shall be so guarded
as to prevent contact therewith either by the worker or by objects carried by
him.

In power plants only the lower run of the belt need be guarded.
( e ) Overhead chain and link drives, where the chain exceeds 2
inches in width, are governed by the same rules as overhead horizon
tal belts and shall be guarded in the same manner as belts.
N ote.— A ll guards to be constructed in accordance with Part IV, section 42,
rule 423.

( / ) American or continuous system rope drives so located that
the condition of the rope (particularly the splice) can not be con
stantly and conveniently observed shall be equipped with a “ tell
tale” device (preferably electric-bell type) that will give warning
when rope begins to fray.
F or guarding o f overhead rope drives see Part IV , section 42,
rule 423.
Rule 221. Vertical and inclined belts.
(a)
Vertical and inclined belts shall be inclosed by a guard con
forming to standards in Part IV , sections 40 and 42.

SAFETY CODE FOR POWER-TRANSMISSION APPARATUS.

(6) A ll guards for inclined belts shall be arranged in such a
manner that a minimum clearance of 6 feet 6 inches is maintained
between belt and floor at any point outside o f guard.
Note.— For exception in case of flat belts 1 inch or less in width or round
belts one-half inch or less in diameter see “ Scope.”

Buie 222. Vertical belts.
Vertical belts running over a lower pulley more than 6 feet above
floor or platform shall be guarded at the bottom in the same manner
as horizontal overhead belts, if conditions are such as stated in rule
220 (<?), 1 and 3.
N ote.— For exception in case of flat belts 1 inch or less in width or round
belts one-half inch or less in diameter see “ Scope.”

Buie 223. Cone-pulley belts.
A cone-pulley drive with all parts o f the lower cone pulley 3 feet
or more above the floor need not be guarded. Where any part o f
the lower cone pulley is less than 3 feet from the floor, the pulley
and belt shall be guarded in accordance with Part IV , sections 40
and 42.
Buie 224. Belt tighteners.
(#) Suspended counterbalanced tighteners and all parts thereof
shall be o f substantial construction and securely fastened; the bear
ings shall be securely capped. Means must be provided to prevent
tightener from falling, in case the belt breaks.
N ote.— See Discussion, Part V I.

(6 ) Where suspended counterweights are used and not guarded
l>y location, they shall be so encased as to prevent accident.
S E C T IO N 23. G E A R S , SP R O C K E TS, A N D C H A IN S .

Buie 230. Gears.
Gears shall be guarded in accordance with one o f the follow ing
specifications:
{ a) A complete inclosure.

(5 ) A standard guard as described in section 42 at least 6 feet high extend
ing 6 inches above the mesh point o f the gears.
(c)
B y a band guard covering the face of gear and having flanges extended
inward beyond the root o f the teeth on the exposed side or sides. W here any
portion o f the train o f gears guarded by a band guard is less than 6 feet from
the floor a disk guard or a complete inclosure to the height o f 6 feet shall be
required.
N ote.— Rule does not apply to hand operated gears used only to adjust ma
chine parts and which do not continue to move after hand power is removed.
However, the guarding of these gears is highly recommended. (See Part V I,
par. 5.)

Buie 231. Sprockets and chains.
A ll sprocket wheels and chains shall be inclosed unless more than
7 feet above the floor or platform .
Note.— This does not apply to manually operated sprockets.

Buie 232. Openings for oiling.
When frequent oiling must be done, openings with hinged or slid
ing self-closing covers shall be provided.

SAFETY CODE FOR POWER-TRANSMISSION APPARATUS.

SECTION 24. FRICTION DRIVES.

Rule 240. Guarding.
( a ) The driving point of all friction drives when exposed to con
tact shall be guarded.
( b ) A ll arm or spoke friction drives and all web friction drives
with holes in the web shall be entirely inclosel.
( c) A ll projecting bolts on friction drives where exposed to con
tact* shall be guarded.
SECTION 25. KEYS, SET SCREWS, AND OTHER PROJECTIONS.

Rule 250. Elimination or guarding.
A ll projecting keys, set screws, and other projections in revolving
parts shall be removed or made flush or guarded by metal cover.
This does not apply to keys or set screws within gear or sprocket cas
ings or other inclosures, nor to keys, set screws, or oil cups in hubs
o f pulleys where they are within the plane of the rim o f the pulley.
It is recommended, however, that no projecting set screws or oil
cups be used in any revolving pulley or part of machinery, even
though they are within the limits stated in the above paragraph.
SECTION 26. COLLARS AND COUPLINGS.

Rule 260. Collars.
A ll revolving collars, including split collars, shall be cylindrical,
and screws or bolts used in collars shall not project beyond the largest
periphery o f the collar.
Rule 261. Couplings.
( a ) Shaft couplings shall be so constructed as to present no hazard
from bolts, nuts, set screws, or revolving surfaces.
Bolts, nuts, and set screws will, however, be permitted where they
are covered with safety sleeves or where they are used parallel with
the shafting and are countersunk or else do not extend beyond the
liange o f the coupling.
N ote.— W hile the use of a rib or clamp type coupling is not recommended
they will be acceptable if the ends o f the fastenings be well within the periphery
of the body of the coupling and the ends of all bolts are flush with or below
the crown of the nut. A ll outside surfaces are to be turned or ground and
outside edges carefully rounded.

(&) The shifting part o f jaw clutches, and the shifting or mecha
nism part o f friction clutch couplings should be attached to the
driven shaft, i. e., the shaft that will be idle when clutch is dis
engaged.
SECTION 27. BEARINGS AND FACILITIES FOR OILING.

Rule 270. Bearings.
( a ) Self-lubricating bearings are recommended.
( b ) A ll drip cups and pans shall be securely fastened.
Rule 271. Ladders.
Wherever portable ladders are used in oiling, repairing, or adjust
ing power-transmission machinery, these ladders shall be equipped
with safety hooks or antislip device at bottom.
N ote.— For standard construction of ladders see “ Safety Code for Ladders.”

SAFETY CODE FOE POWEB-TBANSMISSION APPABATUS.

Rule 272. Oilers’ runways and platforms.
Shall conform to the “ Safety Code fo r F loor and W all Openings,
Railings, and Toe Boards.”

SAFEtv S et Screws

'Square, Head

S fotted Head

H I

Countersunk. Heads with SpecialWrenches

To prevent s e t screw s from backing o ff it Aar
been -foundgood practice* to prick punch threads a fter screw
has been tightened, ft is a/so w e/f to sp o t d h a ftty means
o f drift or ordinary casehardened s e t Screw before in sert
ing s e t screw .

outsail

SAFETY CODE FOE POWEE-TEANSMISSION APPAEATUS.

S h a ft Co u p u Ho*

S p lit Coupling

\So/id Sleeve Coupling

Clamp Coupling tvilA
^S olely S le e v e

- F =F =3
C om p ression Type. C oupling

flanges P roject S qyeid
B olt Meade &.Mu£o.

F la n ge C o u p lin g s

92111°— 24------ 3

PART III.— STARTING AND STOPPING DEVICES.
SECTION 30. CLUTCHES, CUT-OFF COUPLINGS, AND CLUTCH
PULLEYS.

Rule 300. Guarding.
( a ) Clutches, cut-off couplings, or clutch pulleys having projecting
parts, where such clutches are located 7 feet or less above the floor
or working platform, shall be inclosed by a stationary guard con
structed in accordance with these standards (the U type guard is
permissible, see rule 412) *
N ote 1.— W here clutches, cut-off couplings, or clutch pulleys are so situated
within a machine or otherwise guarded by location, the application o f this rule
is within the discretion of the enforcing authority.
N ote 2.— In engine rooms a guard rail, preferably with toe board, will be
permitted instead of the above, provided this room is occupied only by engineroom attendants.
N ote 3.— The use of a bearing support immediately adjacent to a friction
clutch or cut-off coupling being recognized engineering practice, only selflubricating bearings requiring attention at infrequent intervals shall be used in
such locations.

SECTION 31. BELT SHIFTERS, CLUTCHES, SHIPPERS, POLES,
PERCHES, AND FASTENERS.

Rule 310. Belt shifters.
( a ) Tight and loose pulleys on all new installations made subse
quent to the date o f the adoption o f this code shall be equipped with
a permanent belt shifter provided with mechanical means to prevent
belt from creeping from loose to tight pulley.
N ote.— It is recommended that old installations be changed to conform to this
rule.

( b) Belt shifter and clutch handles shall be rounded and be located
as far as possible from danger o f accidental contact, but within easy
reach o f the operator. Where belt shifters are not directly located
over a machine or bench, the handles shall be cut off 6 feet 6 inches
above floor level.
( c ) A ll belt and clutch shifters o f the same type in each shop
should move in the same direction to stop machines, i. e., either all
r ig h t or all left .
N ote.— This does not apply to friction clutch on countershaft carrying two
clutch pulleys with open and crossed belts, respectively.
In this case the
shifter handle has thiee positions and the machine is at a standstill when clutch
handle is in the neutral or center position.

Rule 311. Belt shippers and shipper poles.
The use o f belt poles as substitutes for mechanical shifters is not
recommended. Where necessity compels their use they shall be o f
sufficient size to enable workmen to grasp them securely. (A 2-inch
diameter or 1J by 2 inch cross section is suggested.) Poles shall be
12

SAFETY CODE FOE POWER-TRANSMISSION APPARATUS.

smooth and preferably of straight grain hardwood, such as ash or
hickory. The edges of rectangular poles should be rounded. Poles

fesw taf M f M u l l a i N f U Method* «l Syncing * * * * *

A. The Right Way: Countershaft with Spaces Allowed So That II Belt* Slip Of They
Cannot Wedge and Pell the Counterehaft upon Workmer.
A. The Wrong Way; Countershaft Showing How Belt* May Wedge When They
of Puller* i< liueflciant S^ate it Allowed. Th»» May Reewlt in injary to Week*

Several Types of Sale Belt Perches

should extend from the top of the pulley to within about 40 inches
o f floor or working platform.

SAFETY CODE FOR POWER-TRANSMISSION APPARATUS.

Buie 312. Belt perches.
Where loose pulleys or idlers are not practicable, belt perches in
form o f brackets, rollers, etc., shall be used to- keep idle belts away
from the shafts. Perches should be substantially made and so
designed that the shipping o f belts to> and from them can be safely
accomplished.

S imple type of belt hook ano belt guide to prevent
BELT FROM0ROPPINO BETWEEN PULLEYS ORON TO LINESHAFT,
Buie 313. Belt fasteners.
Belts which o f necessity must be shifted h j hand and belts within
6 feet o f the floor or working platform which are not guarded in
accordance with the intent o f this code shall not be fastened with
metal in any case nor with any other fastening which by construction
or wear will constitute an accident hazard.

PART IY .— GUARD STANDARDS.
S E C T IO N 40. S T A N D A R D

G UARDS— G EN E R AL

R E Q U IR E M E N T S .

Rule 400. Materials.
( а ) Standard conditions will be secured by the use o f the follow
ing materials: Expanded metal, perforated or solid sheet metal, or
wire mesh on a frame o f angle iron or iron pipe securely fastened
to floor or to frame o f machine. (See section 42, rule 402.)
(б ) A ll metal should be free from burrs and sharp edges.
( c)
Wire mesh should be o f the type in which the wires are se
curely fastened at every cross point either by welding, soldering, or
galvanizing, except in case o f diamond or square wire mesh made
o f No. 14 gauge wire, three-fourths inch mesh or heavier.
N ote.— For method of fastening diamond or square wire mesh made o f
crimped wire into frames see rule 402 (3 ).

Rule 401. Design of guards. 9
( a ) Where it is necessary to change belts, make adjustments, or
for the admission o f oil or grease, guards should preferably be
provided with hinged sections or be made removable.
(5) Guards should be designed so as jiot to interfere with the
usual machine operations, but give the maximum protection to the
operator.
Rule 402. Method of manufacture.
(a) Expanded metal, sheet or perforated metal, and wire mesh
shall be securely fastened to frame by one o f the follow ing methods:
(1 ) W ith rivets or bolts spaced not more than 5 inches center to center. In
case of expanded metal of wire mesh, metal strips or clips shall be used to
form a washer for rivets or bolts.
(2 ) B y welding to frame every 4 inches.
(3 ) B y weaving through channel or angle frame, or if No. 14 gauge threefourths inch mesh or heavier is used by bending entirely around rod frames.
(4 ) W here openings in pipe railing are to be filled in with expanded metal,
wire mesh or sheet metal, the filler material shall be made into panels with
rolled edges or bound with V or U edging o f No. 24 gauge or heavier sheet
metal fastened to the panels with bolts or rivets spaced not more than 5 inches
center to center. The bound panels shall be fastened to the railing by sheetmetal clips spaced not more than 5 inches center to center.
N ote.— Diamond or square mesh made of crimped wire fastened into channels,
angle or round iron frames, may also be used as a filler in guards.
Size of mesh -shall correspond to table given .under rule 420.

(6 ) Where the design o f guards requires filler material o f greater
area than 12 square feet, additional frame members shall be pro
vided to maintain panel area within this limit.
(c) A ll joints o f framework shall be made equivalent in strength
to the material o f the frame.

SAFETY CODE FOR POWER-TRANSMISSION APPARATUS.
S E C T IO N 41. D ISK , SH IE L D , A N D “ U ” G U A R D S .

Rule 410. Disk guards.
A disk guard shall consist of a sheet-metal disk not less than No.
22 gauge fastened by U bolts or rivets to spokes o f pulleys, fly
wheels, or gears. Where possibility of contact with sharp edges of
the disk exists, the edge shall be rolled or wired. In all cases the
nuts shall be provided with lock nuts which shall be placed on the
unexposed side o f the wheel.
Rule 411. Shield guards.
( a ) A shield guard shall consist of a frame filled in with wire
mesh, expanded, perforated, or solid sheet metal.
( h) I f area o f shield does not exceed 6 square feet the wire mesh
or expanded metal may be fastened in a framework o f three-eighthsinch solid rod, three-fourths by three-fourths by one-eighth inch
angle iron or metal construction of equivalent strength.
Metal shields may have edges entirely rolled around a threeeighths-inch solid iron rod.
N ote .— All material of shield guard shall meet the requirements of section
42, rule 420.

Rule 412. U Guards.
U guards shall be constructed of jnaterial specified in table,
section 42, rule 420. Edges shall be smooth, and if size o f guard
requires these edges shall be reinforced by rolling, wiring* or by
binding with angle or flat iron.
S E C T IO N 42. A P P R O V E D M A T E R IA L S .

Rule 420. Minimum requirements.
The materials and dimensions specified in this rule shall apply
to all guards except horizontal overhead belts, rope, cable, or chain
guards more than 7 feet above floor or platform. (F or the latter
see table following rule 423.)
(a)

TABLE OF STANDARD MATERIALS AND DIMENSIONS.

Clearance from
moving part at
all points.

Material.

Largest
mesh or
opening
allow
able.
Inches.

Woven wire.................................
Expanded metal....................... .
Perforated metal.........................
Sheet metal.................................
Wood or metal strip crossed......

Wood or metal strip not crossed.
Standard rail...............................

/Under 4 inches.........
14 to 15 inches............
/Under 4inches.........
l4 t o 15inches............
/Under 4inches.........
14 to 15inches............
/Under 4 inches.........
\4 to 15 inches............
fUpder 4 inches.........
\A IU 1IdKlULUCo.
innVioQ . . __•.
11

fTTn/lor
ri/>hao
I UUUCr Ailliyllco........
1
Afl/U
a1
[1
IdKinrdiAc
lULlivD* . . . . . . .

/Minimum, 15 inches.
|\Maximum, 20inches.

Minimum gauge
(U. S. standard)
or thickness.

Minimum
height of
guard from
floor or
platform
level.
Feet.

No. 16....................
No. 12....................
No. 18....................
No. 13....................
No. 20....................
No. 14....................
No. 22....................
No. 22....................
/W ood f i n c h _____
h IMetalNo. 16.........
}
2 / W o o d fin c h .........
IMetalNo. 16......... I
/W o o d fin c h .........
J IMetalNo. 16......... l
/W
o o d fin c h ......... l
l
IMetalNo. 16.........
jSee standard for railings (rule 424.)
2*

5
6

^
ft
5

N ote .— For flat belts 1 inch or less in width or round belts one-half inch

or less in

diameter see “ Scope.”

SAFETY CODE FOR POWER-TRANSMISSION APPARATUS.

( 6 ) Framework .
(1 ) The framework for all guards fastened to floor or working platform and
without other support or bracing shall consist of 1^ by 11 by one-eighth inch
angle iron, metal pipe of 11 inches inside diameter, or metal construction of
equivalent strength. A ll rectangular guards shall have at least four upright
frame members each of which shall be carried to the floor and be securely
fastened thereto.
Cylindrical guards shall have at least three supporting members carried to
floor.
All guards having framework lighter than the above shall be rigidly braced
every three feet of their height to some fixed part of machinery or building
structure.
(2 ) Minimum dimensions of materials for the framework of all guards except
as noted in the following paragraph shall be angle iron 1 by 1 by one-eighth
inch, metal pipe of three-fourths inch inside diameter, or metal construction of
equivalent strength.
(3 ) Guards 30 inches or less in height and with a total surface area not in
excess of 10 square feet may have a framework of three-eighths inch solid rod,
three-fourths by three-fourths by one-eighth inch angle or metal construction
of equivalent strength. The filling material shall correspond to the require
ments of the table under rule 420.
N ote .— This rule is made for the purpose of providing a standard for small
guards not subject to severe stress for use in locations where guards con
structed of framework as specified in the above standards would be cumber
some and unnecessarily expensive.

(<?) The specifications given in ( a ) and ( b ) are the minimum re
quirements ; where guards are exposed to unusual wear or deteriora
tion, heavier material should be used.
B uie 421. W ood guards.
( a ) W ood guards may be used in the woodworking and chemical
industries, in industries where the presence of fumes or where manu
facturing conditions would cause the rapid deterioration of metal
guards; also in construction work and in locations outdoors where
extreme cold or extreme heat make metal guards and railings unde
sirable. In all other industries, wood guards will not be allowed,
except by special permission of the supervising authority.
N ote .— A wood guard unless very carefully constructed is not substantial.
Wood guards are a decided fire hazard, especially when they become saturated
with oil and when they are located near flammable material.

( h) M a t e r ia l a n d construction.
(1 ) Wood shall be sound, tough, and free from any loose knots.
(2) Guards shall be made of planed lumber not less than 1 inch rough
board measure and edges and corners rounded off.
(3 ) Wood guards shall be securely fastened together with wood screws, hard
wood dowel pins, bolts, or rivets.
(4) While no definite dimensions are given under this heading for framework
or filler materials, wood guards shall be equal in strength and rigidity to metal
guards specified in rule 420 (a ), (&), and (c ).
(5 ) For construction of standard wood railing see section 42, rule 424.

B uie 422. Guards fo r horizontal overhead belts.
{ a ) Guards for horizontal overhead belts shall run the entire
length o f the belt and follow the line of the pulley to the ceiling or
be carried to the nearest wall, thus inclosing the belt effectively.
Where belts are so located as to make it impracticable to carry the
guard to wall or ceiling, construction of guard shall be such as to
inclose completely the top and bottom runs of belt and the face o f
pulleys. (See rule 220 (5) and (d).)

SAFETY CODE FOR POWER-TRANSMISSION APPARATUS.

(6) The guard and all its supporting members shall be securely
fastened to wall or ceiling by gimlet-point lag screws or through
bolts. In case of masonry construction, expansion bolts shall be
used. The use o f bolts placed horizontally through floor beams or
ceiling rafters is recommended.

GUARD CONSTRUCTION

Jj"©1
toftfoiwno w M tr nnni

eorno omccrcMOANtue

m m
H ltllllS IlQ

H AT STRIP

lillB IV X Iltl'

fw r r t D (o n e o tT c rtT R

ANCIC t o H k$ t c w r u i w

I ' ItllU r

******

o h

X*VNP * * * * * * .

(o ) Suitable reinforcement shall be provided for the ceiling rafters
or overhead floor beams, where such is necessary, to sustain safely the
weight and stress likely to be imposed by the guard. The interior
surface o f all guards, by which is meant the surface o f the guard
with which a belt will come in contact, shall be smooth and free from

SAFETY CODE FOR POWER-TRAJSTSMISSION APPARATUS.

all projections of any character, except where construction demands
it; protruding shallow round-head rivets may be used. Overhead
belt guards shall be at least one-quarter wider than the belt which
they protect, except that this clearance need not in any case exceed
6 inches on each side. Overhead rope drive and block and roller
chain drive guards shall be not less than 6 inches wider than the
drive on each side.
In overhead silent chain-drive guards where the chain is held from
lateral displacement on the sprockets the side clearances required on
drives o f 20-inch centers or under shall be not less than one-fourth
inch from the nearest moving chain part and on drives o f over
20-inch centers a minimum o f one-half inch from the nearest moving
chain part.
( d ) The table following rule 423 gives sizes of materials to be used
and general construction of guards for belts 10 inches or more in
width. No material for overhead belt guards should be smaller than
that specified in this table for belts 10 to 14 inches wide, even i f the
belt is less than 10 inches in width. However, No. 20 gauge sheet
pietal may be used as a filler on guards for belts less than 10 inches
wide. Expanded metal, because of the sharp edges, should not be
used as a filler in horizontal belt guards.
( e ) For clearance between guards and belts, ropes, or chains o f
various center to center dimensions between the shafts see bottom o f
table following rule 423.
R ule 423. Guards fo r horizontal overhead rope and chain drives.

Overhead rope and chain drive guard construction shall conform
to the rules for overhead-belt guard construction o f similar width,
except that the filler material shall be of the solid type as shown in
the table unless the fire hazard demands the use of open construction.
A side guard member o f the same solid filling material should be
carried up in a vertical position 2 inches above the level o f the
lower run o f the rope or chain drive and 2 inches within the periph
ery o f the pulleys which the guard incloses, thus forming a trough.
These side filler members should be reinforced on the edges with
1| by one-fourtli inch flat steel, riveted to the filling material at
not greater than 8-incli centers; the reinforcing strip should be
fastened or bolted to all guard supporting members with at least
one three-eighths inch rivet or bolt at each intersection, and the
ends should be secured to the ceiling with lag screws or bolts. The
filling material shall be fastened to the framework o f the guard
and the filler supports by three-sixteenths inch rivets spaced on 4inch centers. The width o f the multiple drive shall be determined
by measuring the distance from the outside o f the first to the outside
o f the last rope or chain in the group accommodated by the pulley.
R ule 424. Guard rails and toe boards.
( a ) Guard rail shall be 42 inches in height, with mid rail between
top rail and floor.
( b ) Posts shall be not more than 8 feet apart; they are to be per
manent and substantial, smooth, and free from protruding nails,
bolts, and splinters. I f made of pipe, it shall be 1| inches inside
diameter, or larger. I f made of metal shapes or bars, their section
shall be equal in strength to that of 1| by
by
inch angle

SAFETY CODE FOE POWER-TRANSMISSION APPARATUS.

iron. I f made o f wood, the posts shall be 2 by 4 inches or larger.
The upper rail shall be 2 by 4 inches, or two 1 by 4 strips, one at
the top and one at the side of posts. The mid rail may be 1 by 4
inches or more. The rails (metal shapes, metal bars, or w ood),
should be on that side o f the posts which gives the best protection
and support. Where panels are fitted with expanded metal or wire
mesh as noted in table, 420 (&), the middle rails may be omitted.
(c )
Toe boards shall be 4 inches or more in height, of wood, metal,
or o f metal grill not exceeding 1 inch mesh. Toe boards at flywheel
pits should preferably be placed as close to edge o f the pit as
possible.

HORIZONTAL OVERHEAD BELTS, ROPES, AND CHAINS 7 FEET OR MORE ABOVE FLOOR OR PLATFORM

id t h .

Material.
Over 10" to 14" inclusive.

Framework...............................................
Filler (belt guards)...................................
Filler and vertical side member..............
Filler supports..........................................
Guard supports........................................

IX "

I X " X M " ..

IX” * ft.” ......

No. 20 A. W. G ...
2" x A " flatiron .
2" x f t " ...............

Over 24".

Over 14" to 24" inclusive.

2 " x 2 " x f t ” ..............................

2" x •&"
No. 18 A. W . G *.*! * .*
2" x % " flat iron.........................
2" x % " ...................................... .

3 " x 3 " x % " ................................
2 " x f t " .......................................
No. 18 A .W .G ...........................
2 X " x 2X ” x X " angle...............
2 ^ " x ^ " .....................................

Angle iron.
Flatiron.
Solid sheet metal.
Flat and angle.
Flatiron.

FASTENINGS.

Filler supports to framework...................................
(3) X " .....................................
( 2 ) * " ..................
Filler flats to supports (belt guards)............................ < ! ) * " .................
m » = v . = .
Filler to frame and supports (rope and chain guards j... f t " rivets spaced..
oliXtom:....................
8 " centers on sides and 4"
Guard supports to framework.................................
( 2) f t " . .................................................... ( 2) X ” .............................................
Guard and supports to overhead ceiling.................
' x Z X " lag screws or X " bolts. Vs" x 4" lag screws or % " bolts.. X " x 6" lag screws or X " bolts..

Rivets.
Flush rivets.
Rivets or bolts.
Lag screws or bolts.

DETAILS— SPACING, ETC.

Width of guards........................................................
.Spacing between filler supports...............................
Spacing between filler flats (belt guards)...............
Spacing between guard supports.............................

One-quarter wider than belt, rope, or chain drive.
20" C. toC
16" C .to C .
2" apart...
2 X " apart..
36" C. to C
36" C .to C .

16" C. toC .,
3" apart___
36" C. to C .

OTHER BELT GUARD FILLING PERMITTED.

Sheet metal fastened as in rope and chain guards....... No. 20 A. W. G............................. No. 18 A . W . G ...........................
Woven wire, 2" mesh....................................................! No. 12 A. W. G ............................. No. 10 A. W . G ...........................

No. 18 A. W. G . . . .
No. 8 A. W . G .......

Solid or perforated.

CLEARANCE FROM OUTSIDE OF BELT, ROPE, OR CHAIN DRIVE TO GUARD.

Distance center to center of shafts.................
Clearance from belt, rope, or chain to guard.

Up to 15' inclusive........................ Over 15' to 25' inclusive.............. Over 25' to 40' inclusive.............. Over 40'.
10"................................................ 15"................................................. 20" .
1

SAFETY COWS FOB POWEK-TKANEMISSION APPAKATUS,

Guard.

SAFETY CODE FOR POWER-TRANSMISSION APPARATUS.

PART V.— OPERATING RULES.
SE C TIO N 50. C A R E O F E Q U IP M E N T .

Rule 500. General.
A ll power^transmission equipment shall be inspected at intervals
not exceeding 60 days and be kept in good working condition at all
times.
Rule 501. Shafting.
{ a ) Shafting shall be kept in alignment, free from rust, and ex
cess oil or grease.
( b ) Where explosives, explosive dusts, flammable vapors, or flam
mable liquids exist, the hazard of static sparks from shafting shall
be carefully considered.
N ote .— Static electricity m a y be removed by means of a spring copper brush
in contact with the shafting. This brush must be well grounded through No.
12 insulated copper wire. Other effective methods may be used.

Rule 502. Bearings.
Bearings shall be kept in alignment and properly adjusted.
Rule 503. Hangers.
Hangers shall be inspected to make certain that all supporting
bolts and screws are tight and that supports of hanger boxes are
adjusted properly.
Rule 504. Pulleys.
( a ) Pulleys shall be kept in proper alignment to prevent belts
from running off.
( b ) Both driving and driven pulleys carrying a nonshifting belt
should have crowned faces.
(o) Cast-iron pulleys should be tested frequently with a hammer
to disclose cracks in rim or spokes. It should be borne in mind
that the sound is usually much different if the belt is or is not
on the pulley.
(d)
Split pulleys should be inspected to ascertain if all bolts
holding together the sections o f the pulley are tight.
Rule 505. Care of belts.
{ a ) Quarter-twist belts when installed without an idler can be
used on drives running in one direction only. They will run off a
pulley when direction of motion is reversed.
( b ) Inspection shall be made of belts, lacings, and fasteners and
such equipment kept in good repair.
(<?) Where possible, dressing should not be applied when belt or
rope is in motion; but, i f this is necessary, it should be applied where
belts or rope leave pulley, not where they approach. The same
precautions apply to lubricating chains.
(d)
The hazard of static electricity from belts shall be carefully
considered where explosives, explosive dusts, flammable vapors, or
flammable liquids exist.

SAFETY CODE FOE POWER-TRANSMISSION APPARATUS.

N ote .— Static electricity may be removed from belts by means of metallic
flexible-tooth combs the same width as the belts. One comb should be placed
within 10 inches of the line of contact where the belt leaves each pulley or
flywheel. These combs should be in contact with and placed transversely to
the belt and also be well grounded with No. 12 insulated copper wire. The
teeth of the comb should point in the direction of the belt motion.
Other
effective methods may be used.

R ule 506. Belts on overhead pulleys.

A belt pole should be used to throw off or put on belts.
In unshipping a belt it should always be thrown off the driving
pulley, not the driven.
It is advisable to have one experienced man to take care o f over
head belts and put them on and take them off pulleys.
Belts should not be allowed to ride on shafting but should be
held from same either by loop or belt perch. (See rule 312.)
R ule 507. Lubrication.

The regular oilers shall wear tight-fitting clothing and should
use cans with long spouts to keep their hands out o f danger.
Machinery shall be oiled when not in motion, wherever possible.

PART VI.— DISCUSSION.
1. B ro k e n p u lle y s .—Under section 21, rule 212 states that pulleys
with small pieces broken out o f rim shall not be used. The rough
edges formed by pieces broken out o f pulley rim offer a decided acci
dent hazard in case anyone should come in contact with the rough
edge o f the pulley rim. Considerable unnecessary wear on the belt
is also caused.
2. B e lt tig h te n e rs .—Under section 22, rule 223 states that belt
tighteners o f the suspended type shall be arranged in such a way as
to prevent falling on any person below, should the belt break: or
throw tightener. This can be accomplished by securely fastening
cables or chains o f sufficient strength to the tightener and to the roof,
or some substantial object above, to prevent it from falling far
enough to strike a person.
3. P o w e r c o n tro l .—Among the methods used for power control
may be mentioned motor switches, friction clutches, belt shifters, and
engine stops. The means for controlling power should be positive
and should be so arranged as to permit o f operation from a point
not more than 100 feet from any machine driven, from the source of
power in question. I f the stations can be arranged to be within 50
feet o f any machine, it is highly advisable. There will be cases, as
for example in the steel industry, where a greater distance from the
machine becomes necessary.
It is advisable to mark the stop station with a mark easily dis
tinguishable—green bands on posts and green circles on walls are
recommended, together with a sign “ Stop station” or “ Emergency
stop.” A light o f characteristic color should be added in shops where
night work is carried on.
A ll electrical safety devices should operate by the opening o f a
n o rm a lly closed c irc u it. Any failure of the current or device will
thus be indicated by the stopping of the prime mover. It is ad
visable to test such devices daily by shutting off the power at noon
or night by such means.
4. P o w e r-tran s m is s io n equ ip m e n t .—Rule 204 states certain condi
tions under which the guarding o f power-transmission equipment
may be modified. This rule was inserted because frequently in paper
or saw mills, woodworking plants, etc., transmission equipment is lo
cated in basements, lofts, or transmission towers not used for any
other purpose, and it would be a hardship to require the complete
guarding o f this apparatus.
5. H a n d -o p e ra te d gears .—The note under rule 230 states that
hand-operated gears need not be equipped with guards. Quite fre
quently, however, such gears are operated by a short lever or crank,
and wnen the operator braces himself against the frame o f the ma
chine he is likely to come in contact with the gears. It is always
good practice to look into this matter carefully, and wherever there
is the slightest chance o f injury it is well to provide guards.

S A F E T Y CODE FOB P O W E B -T B A H S M IS S IO N

A PPA B A T TJS.

6.
H o r iz o n ta l overhead belts .—Kule 220 ( c) covers guarding of
horizontal overhead belts more than 7 feet above floor or platform.
It is a difficult proposition to decide which overhead belts need
guarding and which can be left exposed. These belts, under certain
operating conditions, offer a decided accident hazard in case they
break. Any belt transmitting power is subjected to a certain stress
which increases with the load and the speed. In case this belt
breaks this force is reduced somewhat, due to the fact that the driv
ing power is eliminated. The belt is impelled only by its momentum,
but this is usually sufficient to give it a decided whipping force
strong enough to cause considerable damage. This question of
overhead belts located more than 7 feet above floor or working plat
form is well worth investigating as the cost o f one serious accident
might suffice to pay for quite a number of guards.

FART VII.— REFERENCES,
The safety codes printed in the list below are those dealing with
subjects other than mechanical power-transmission apparatus but
related in some way to this code. These codes, when completed and
approved, will be known as “ American standard” or “ Tentative
American standard ” codes and may be obtained from the American
Engineering Standards Committee, 29 West Thirty-ninth Street,
New York.
APPROVED AND PUBLISHED.
Abrasive Wheels, Safety Code for the Use, Care and Protection of.
Explosives, Permissible Specifications for the Testing and Use of.
Foundries, Safety Code for the Protection of Industrial Workers in.
Heads and Eyes of Industrial Workers, Safety Code for the Protection of.
Ladders, Safety Code for.
Lighting Factories, Mills, and Other Work Places, Code for.
Power Presses and Foot and Hand Presses, Safety Code for.

CODES IN PROCESS OF DEVELOPMENT.
Aeronautics, Safety Code for.
Automobile Brakes and Brake Testing, Safety Code for.
Building Exits, Safety Code for.
Compressed A ir Machinery, Safety Code for.
Construction Work, Safety Code for.
Conveyors and Conveying Machinery, Safety Code for.
Cutting and W elding Operations, Safety Code for.
Electrical Equipment in Coal Mines, Safety Rules for Installing and Using.
Electrical Fire and Safety Code.
Electrical Code, National.
Electrical Safety Code.
Elevators and Escalators, Safety Code for.
Exhaust Systems, Safety Code for.
Explosives, Safety Code for the Use of.
Floor and W a ll Openings, Railings and Toe Boards, Safety Code for.
Forging and Hot Stamping, Safety Code on.
Gas Safety Code.
Lamps, Electric Mine, Permissible Portable.
Laundry Machinery and Operations, Safety Code for.
Lighting of School Buildings, Safety Code for.
Lightning Protection, Safety Code for.
Locomotives, Storage Battery, for Use in Gaseous Mines.
Logging and Sawmill Machinery, Safety Code for.
Paper and Pulp Mills, Safety Code for.
Piping Systems, Indentification of.
Plate and Sheet Metal Working, Safety Code for.
Power Control, Electrical, Safety Code for.
Power Control Apparatus, Mechanical, Safety Code for.
Refrigeration, Mechanical, Safety Code for.
Sanitation, Industrial, Safety Code for.
Tanneries, Safety Code for.
Textiles, Safety Code for.
Tools, Machine, Safety Code for.
Traffic Signals, Colors for.
Ventilation Safety Code.
Walkway Surfaces, Safety Code for.
Woodworking Machinery, Safety Code for.

IN D E X
Part Section

B
Basements, etc., shafting
located in.........................
Bearings......... - ...................
Care o f..........................
Facilities for oiling.......
B elts:.
And ropes, horizontal - .
Care of-.........................
Cone-pulley..................
Drives, belt, rope, and
chain.
Guides...........................
Horizontal overhead.
Discussion o f rules...
Horizontal overhead,
guards for...................
On overhead pulleys,
operating rule............
Perches.........................
Shifters..........................
Shifters, clutches, ship
pers, poles, perches,
and fasteners..............
Shippers and shipper
poles...........................
Tighteners....................
Tighteners, discussion
of rules.......................
Vertical.........................
Vertical and inclined-..

Chain, belt, and rope drives.
Chain and rope drives, hori
zontal overhead, guards
for.....................................
Chains and sprockets.........
Chain, sprockets, and gears.
Clutches, shifters, shippers,
poles, perches, and fasten
ers, belt.............................
Clutches, cut-off couplings,
and clutch pulleys...........
Codes, approved and pub
lished, list of.....................
Codes in process o f develop
ment, list o f......................
Collars and coupling...........
Collars, revolving and split.
Composition and wood
pulleys..............................
Cone-pulley belts.............. .
Connecting rods and crank:
Corrosion, pulleys exposed
to..................................... .
Couplings...........................
Couplings and collars.........
Cranks and connecting rods
Cut-off couplings, clutches,
and clutch pulleys...........

2
2
5
2

20
27
50
27

204
270
502
270-272

2
5
2

22
50
22

220
505
223

2
3
2

22 220-224
31
313
214
21

6
4

422

5
3
3

50
31
31

506
312
310

310-313

3
2

31
22

311
223

6
2
2

22
22

222
221

220-224

4
2
2

42
23
23

423
231
230-232

310-313

300

7
7
2
2

26
26

260-261
260

2
2
1

21
22
H)

215
223
101

2
2
2 •
1
3

21
26
26
10
30

Rule

216
261
260-261
101
300

Drives, belt, rope, and
chain................................
Drives, friction....................
E
Equipment:
Care o f..........................
Mechanical p o w e r transmission..............
Periodic inspection o f. Extension piston rods.........

500-507
200-204
500

102

F
Fasteners, shifters, clutches,
s h ip p e r s , poles, and
perches, b e lt....................
Flywheels............................
Friction drives.....................

310-313
100
240

G
Gears....................................
Hand-operated, discus
sion o f rules...............
Sprockets, and chains..
Governor balls....................
Guards:
Approved materials___
Clutches, cut-off cou
plings, and clutch pul
leys.............................
Design of—....................
Friction drives..............
Horizontal overhead
belts...........................
Horizontal overhead
rope and chain drives.
Horizontal shafting___
Keys, set screws, and
other projections___
Method of manufac
ture........................... .
M in im u m r e q u ire
ments, materials and
dimensions............ .
Pulleys.........................
Rails and toe boards...
Standard materials fo r.
Standards.................... .
Vertical and inclined
shafting.................... .
W ood. Approved ma
terials and dimen
sions...........................

230

23
10

230-232
103

420-424

30
40
24

300
401
240

422

423

201

250

402

420
210

42
40
40-42

400
400-424

202

421

503

200

250

424

H
Hangers, care and inspec
tion o f............................. .
I
Installation of shafting.......
Interpretaion......... Page 1

Definitions.............. Page 2
Design o f guards.................
Discussion o f rules..............
Disk guards™ ___________
Disk, shields, and “ U ”
guards..............................

220-224
240

4
6
4

401

410

410-412

Keys, set screws, and other
projections, elimination
or guarding......................

INDEX,

P jrt Section

Rule

Part Section

L
Ladders...................................
Lubrication, o p e r a t i n g
rule.......................................

271

507

R o p e , b e l t , an d c h a in
drives................................
Ropes and belts, horizontal.
Runways and platforms,
oilers’ ................................

Rule

2
2

22
22

220-224
220

272

2
2
2
5
2

25
250
20
203
20 200-204
50
501
20
201

202

4
4

41
41

410-412
411

3
2
2

31
23
23

311
231
230-2
400-402

M
Materials, for standard
guards................................ .
Mechanical power-trans
mission equipment............

S
4

400

200-204

0
Oilers’ runways and plat
form s.......... .......................
Oiling, facilities for, and
bearings...............................
Oiling, openings for..............
Openings for oiling...............
Operating rules.....................

272

2
2
2
5

27
23
23
50

270-272
232
232
500-507

3
1

31
10

310-313
102

272

310-313

P
Perches, fasteners, shifters,
clutches, shippers, ana
poles, belt__________ ____
Piston rods, extension_____
Platforms and runways,
oilers’ ...................................
Poles, perches, fasteners,
shifters, clutches, and
shippers, b e lt .....................
Power control. Discussion
of r u le s .................. ............
Power-transmission equip
ment. Discussion of rules.
Power-transmission equip
ment, mechanical_______
Prime movers and guards..
Projections, set screws, and
k e y s ? e lim in a tio n or
guarding..............................
Pulleys..................... ..............
Broken. Discussion of
rules.............................
Broken, not to be used.
Care of.........................
Exposed to corrosion.__
Location of......................
Out of service.................
Speeds..............................
W ood and com position.

Scope.......... ............ Page 1
Set screws, keys, and other
projections, elim ination
or guarding_______ _____
Shaft ends, projecting_____
S hafting.............................
Care of......................... .
Horizontal, guarding...
Located in basements,
etc..............................
Vertical and inclined,
guarding............ ........
Shield, disk, and “ U ”
guards...............................
Shield guards____________
Shipper poles and belt ship
pers............... .............. . . .
Sprockets and chains........ .
Sprockets, gears, and chains.
Standard guards, general re
quirements.................... .
Standard guards, method
of manufacture_________
Starting and stopping de
vices........................... ......

Tail rods or extension pis
ton rods_________ ____
Toe boards and guard rails.

2
1

20
10

200-204
100-103

2
2

25
21

250
210-217

402

30,31

300-313

1
4

10
42

102
424

412

410-412

2
2
2

22
22
20

221
222
202

421

6
2
5
2
2
2
2
2

21
50
21
2i
21
21
21

212
504
216
211
217
213
215

“ U ” guards.........................
“ U ,” disk, and shield
guards......... ....................
V
Vertical and inclined belts.
Vertical belts_____________
Vertical shafting, guarding.
W

R
References..............................
R o p e a n d ch a in d r iv e s ,
h o r iz o n t a l o v e r h e a d ,
guards for............................

204

7
4

423

W ood and composition pul
leys...................................
W ood guards, approved
materials...........................

Full text of Safety Code for Mechanical Power-Transmission Apparatus : Bulletin of the United States Bureau of Labor Statistics, No. 364

FRASER