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REAL ESTATE
Hi
AND
(Copyright, 1917, by The Record and. Guide Co.)
NEW YORK, JUNE 23, 1917
SAFETY PRINCIPLES APPLIED TO ELEVATORS
Many Accidents Avoidable If Proper Precautions Are
Taken—Safety Must Be Combined With Art and Efficiency
C" LE\/\TOR accidents, like other in-
•'—' diistrial accidents, are largely pre¬
ventable if recognized safety principles
arc properly applied to the physical
equipment, and if tlie elevator operator
is properly instructed in right methods
of operation under normal and emer¬
gency conditions.
Accidents are the results of hazards,
and hazards are faults in men, methods
or materials. The elimination of haz¬
ards is the elimination of these faults.
Ignorance on the part of an elevator op¬
erator is a hazard to be eliminated by
education and instruction. Faulty ma¬
terials in car, shaft or hoisting mechan¬
ism are hazards to be eliminated by
proper materials. Unsafe practices and
methods of operation are hazards to
be eliminated by omission entirely of
the function, or if tlie function is nec¬
essary, by the substitution of another
inethod that is safer and easier than the
old method.
These evolutions or transformations
in men, methods and materials are ap¬
plications of safety principles, which are
now being rapidly standardized. There
are, of course, misapplications of prin¬
ciples which have brou.ght forth severe
criticism and. in some cases, ridicule;
but we must exoect some misapplica¬
tions, on account of the newness of the
subject and correct thein when we en¬
counter them. With elevator equip¬
ment, our great safety principle is that
each and every niece of that equipment
must offer the highest possible degree
of safety to all persons who are in any
way affected by its presence. The sec¬
ond is that safetv must not be used
instead of art and efficiency, but must
be combined with art and efficiency in
such a way as to be always present and
at the same time to gain favor with
the artist, the efficiency engineer and
the public. But in gaining this favor,
the application of the principles must
provide protection from physical, men¬
tal and moral accident hazards.
Let us assume, therefore, a typical
elevator installation of modern type and
look for points that might be improved
in such a way as to reduce incidental
accident hazards without interfering wifh
efficiency of operation and at the same
time outline the general requirements of
elevator equipment, in so far as they re¬
late to mechanical features and physical
hazards.
Starting with the rnachine, which con¬
sists of sheaves, cables and some mech-
anisin for transforming the energy as
received to contfollable tension in the
cables. All parts of this machine should
be designed and constructed to give
strength, durability and reliability by
embodying ample factors of safety based
on the car loaded to capacity, with due
consideration for the physical proper¬
ties of material employed and the nature
of the loads encountered^. If the ma;
chine is overhead, it sliould be sup¬
ported on a strong frame with a con¬
tinuous, level floor surrounding _ all
parts that require oiling or adjusting.
The roorii containing the machine
should be well lighted and ventilated.
•Mr. Hansen is the Chairman of the Com¬
mittee on Health and Safety of the National
Aesoeiation of Manufacturers.
By CARL M. HANSEN*
regardless of location. Darkness breeds
tilth and interferes with good house¬
keeping. This requirement is too often
neglected. This room should be pro¬
vided with an effective lock and kept
locked at all times against all unauthor¬
ized persons.
If the machine is electrically operated,
all switches, panelboards and current
carrying parts should be enclosed in
grounded metal cases to effectively pre¬
vent the accidental contact of persons
with live parts of the equipment. All
wiring, of course, should be thoroughly
protected in conformity with the best
modern electrical practice.
Mechanism to Be Enclosed.
All revolving parts of the mechanism,
especially gears and projecting parts,
should be enclosed to prevent acciden¬
tal contact with, or injury to the oilers,
and other maintenance men; these en¬
closures may be solid sheet metal or
perforated metal, depending on the na¬
ture of the hazard. Wooden guards are
apt to increase the fire hazard, espe¬
cially if the elevator is electrically driv¬
en. Generally speaking a metal guard
offers superior protection.
In the case of a hydraulic machine,
provision must be made for renewal and
readjustments of valves and proper set¬
ting should be maintained at all times.
Plunger and valve glands must be kept
tight enough to prevent leakage. Creep-
age is a fault so nearly universally com¬
mon to hydraulic elevators to be re¬
garded as an inherent hazard, and must
always be considered as an important
feature in the total accident hazard.
.•\niong the accessories necessary for
all types of machines are automatic
stops to limit upward and downward
motion of the supporting cables and
control of the source of power.
There should be a reliable governor
on all machines to prevent car speeds
greater than those for which the car
is designed. The iinpact force of a
car stopped suddenly increases with the
speed. Essential parts are designed to
withstand these loads only at the ma.xi¬
mum specified speeds.
Cable Requirements.
For all passenger and freight cars
and counterweights, there should be
two or more cables of cast steel or soft
iron, preferably of a smaller diameter,
that .is }/2-inch to 'i-jnch in diameter.
These cables should be fastened in a
1 eliable manner to the cars and counter-
wei.ghts. One method which has proved
to be reliable employs a conical cast¬
ing through which the cable is passed,
the strands separated, turned in and
the remaining space filled with solder.
Ii" this method is used, the cable must
be carefullv "pickled" and cleaned to
give the best results.
A new set of cables capable of with-
standin.g a load 10 times as great as
that to which it is subjected when the
car is loaded to capacity and operated
normally is considered sufficient' fo'r a
larse maiority of cases.
The minimum diameter of sheave for
any cable is given bv reliable manufac¬
turers and these sizes should, in all
cases, be adhered to, smaller sheaves
often causing rapid deterioration of the
cable. In general, the ratio of the diam¬
eter of the sheave to the diameter of the
cable should be about 60 to 1. Varia¬
tions therefrom depend on the number
and size of strands in the cable and
material of which they are made; in
other words, on flexibility and elesticity
of the cable:
The size and shape of grooves for dif¬
ferent cables is a prime factor in the de¬
sign of the sheave; if the cable binds,
natural rotation is prevented and in¬
ternal strains are introduced which
sometimes result in a broken cable.
The grooves do not always retain
their original shape under operation.
The cable sometimes cuts the groove
to a new shape and the groove some¬
times cuts the cable, depending on com¬
parative hardness. Either condition re¬
quires the attention of a trained attend¬
ant, and should, in no case, be allowed
to exist until a critical condition appears.
External vigilance bv frequent inspec¬
tions, regrooving the sheaves and re¬
moval of cables before they reach a
dangerous condition is the price of cable
security.
There should always be a shaft en¬
closed in fire retarding partitions with
doors over all openings that are suitable
for stopping persons and fire from pass¬
ing through the opening.
The absence" of an enclosed shaft has
caused many serious and fatal acci¬
dents. It is common practice in too
many places to install freight elevators
without a shaft of any kind. Too much
cannot be said against this practice.
There also are elevator installations
where the hatchway openings are par¬
tially enclosed by a fence, and there are
hatchways with automatic trapdoors,
and still other combinations of protec¬
tive devices which are compromises be¬
tween minimum and maximum protec¬
tion. The shaft has been recognized as
a necessity to protect crowds and pre¬
vent catastrophes for a long time, but
its restricted use, which is largely con¬
fined to passenger elevators, would in¬
dicate that this measure has been consid¬
ered extravagant where only one or a
few persons are exposed to the hazard.
No doubt, the hazards of open hatch¬
ways are more serious on passenger
elevators than on freight, the hazard be¬
ing proportional to number of users,
but nevertheless, they are serious enough
in the case of freight elevators in this
day of workmen's compensation, and
should be eliminated by use of stand¬
ard shafts and doors in all cases.
Open hatchways or shafts enclosed bv
llaiTimable partitions are a menace in
so far as the fire hazard to property is
concerned, but an open hatchway is a
far more serious hazard to persons than
to property, because fire is one of the
hazards to life; the same fire that de¬
stroys property may also destroy life,
and in addition to fire hazard to per¬
sons, there is the danarer of any occu¬
pant on any floor taking a fatal fall
through the floor openings; and there is
also the danger of shearing between
k;nfiing and car floor.
Now with the shaft enclosed in fire-
rtsisting walls, there must be a door at
each floor. This door, as previously
slated, should offer a high resistance
to heat transmission and should be eas¬
ily and safely operable. The door
RECORD .VND GUIDE IS IN ITS FIFTIETH YE.VH OK CONTINUOUS PUBLICATION.