Lifts are sometimes called Elevators which lift people and/or equipment to certain landing levels.
They are classified on the basis of driving methods, thereby, using different design principles and
different methods of construction of components. The following are the three major classifications,
generally, recognized by the designers and manufacturers:
(a) Electric lifts
(b) Hydraulic lifts
(c) Pneumatic lifts.
A typical panoramic view of the lift in operation is given in Fig. (1.1).
Escalators are also used in modes of vertical transportation and are placed in inclined positions
steps rising and flattering. Fig. (1.2) shows a typical layout of an escalator.Adescription of escalator
components is also given.
The Travelators or moving walkways are identical to Escalators, except their surface along the
travel are smooth from end to end. They can be inclined and horizontal during the travel. Fig. (1.3)
shows a typical layout of a travelator or moving walkway. They are sometime called Passenger
They are installed in major commercial buildings such as airports, department stores and underground
metro stations etc. Their functions are to transport majority passengers and their escorted
or unescorted luggage.
Safety, reliability and efficiency shall be all hallmarks of lifts, escalators, and travelators. The
technical data for each one together with specifications and methods of analysis are fully dealt with
under each caption later on in the text.
Compensating ropes with tensioning pulleys shall be used if the rated speed of the lift exceeds
2.5 m/s, and the following conditions shall apply:
(a) the tension shall be provided by gravity;
(b) the tension shall be checked by an electric safety device in conformity with the requirements;
(c) the ratio between the pitch diameter of the pulleys and the nominal diameter of the compensating
ropes shall be at least 30.
When the rated speed exceeds 3.5 m/s an anti-rebound should be provided. The operation of
the anti-rebound device shall initiate the stopping of the lift machine by means of an electric
Protection of sprockets and pulleys used for diversion, reeving and compensation
Devices shall be provided to avoid:
(a) bodily injury;
(b) the rope leaving their grooves, or the chains leaving their sprockets, if slack;
(c) the introduction of objects between ropes (or chains) and grooves (or sprockets).
The devices used shall be so constructed that they do not hinder inspection or maintenance of
the pulleys or sprockets.
Figure (2.8) shows choices of the suspension ropes.
Figure (2.9) gives sheaves and grooves, the functions of which are described earlier, and systems
Overspeed governor ropes
The overspeed governor shall be driven by a very flexible wire rope.
The breaking load of the rope shall be related by a safety factor of at least 8 to the tensile force
produced in the rope of the overspeed governor when tripped.
The nominal rope diameter shall be at least 6 mm.
The ratio between the pitch diameter of the overspeed governor pulley and the nominal rope
diameter shall be at least 30.
The rope shall be tensioned by a tensioning pulley. This pulley (or its tensioning weight) shall
be guided. During the engagement of the safety gear, the governor rope and its attachments shall
remain intact, even in the case of a braking distance greater than normal.
The rope shall be easily detachable from the safety gear.
The following formula shall be satisfied:
× C1 × C2 ≤ e fa (2.17)
T1/T2 =ratio between the greater and the smaller static force in the portions of rope situated on
either side of the traction sheave in the following cases:
car stationary at the lowest landing with a load equivalent to 125% of the rated load;
car stationary at the highest landing level, unloaded.
C1 =coefficient taking account of acceleration, deceleration and specific conditions of the
C1 = gn + a
gn − a
gn =standard acceleration of free fall (m/s2);
a=breaking deceleration of the car (m/s2).
The following minimum values of C1 may be permitted:
1.10 for rated speeds 0<v≤0.63 m/s;
1.15 for rated speeds 0.63 m/s <v≤1.00 m/s;
1.20 for rated speeds 1.00 m/s <v≤1.60 m/s;
1.25 for rated speeds 1.60 m/s <v≤2.50 m/s.
For rated speeds exceeding 2.50 m/s, C1 shall be calculated for each specific case but shall not be
less than 1.25.
C2 =coefficient taking account of the variation in profile of the groove due to wear;
C2 =1 for semicircular or undercut grooves;
C2 =1.2 for vee grooves;
e=base for natural logarithms;
f =friction factor of the ropes in the grooves;
f = μ
for vee grooves; (2.19)
f = 4μ(1 − sin β/2)
π − β − sin β
for semicircular grooves or undercut grooves. (2.20)
α=angle of wrap of the ropes on the traction sheave (rad);
β=angle of the undercut grooves or semicircular grooves on the traction sheave (rad) (β=0
for semicircular grooves) given in Figure (2.9);
γ =angle of the vee grooves in the traction sheave (rad) as shown in Figure (2.9);
μ=coefficient of friction between steel ropes and cast iron pulleys=0.09.
Specific pressure of the ropes in the grooves.
The specific pressure is calculated according to the following formulae:
p = T
× 8 cos β/2
π − β − sin β
for undercut or semicircular grooves; (2.21)
p = T
for vee grooves. (2.22)
In no case shall the specific pressure of the ropes exceed the following value, with the car loaded
with its rated load:
p ≤ 12.5 + 4vc
1 + vc
It is the responsibility of the manufacturer to take account of the individual characteristics and the
conditions of use in the choice of pressure.
d = diameters of the ropes (mm);
D = diameter of the traction sheave (mm);
n = number of ropes;
p = specific pressure (N/mm2);
T = static force in the ropes to the car at the
level of the traction sheave, when the car is stationary
at the lowest landing level with its rated load (N);
vc = speed of the ropes corresponding to the rated speed of the car (m/s).
Type of rope fastenings
The car and counterweight ends of suspension wire ropes, or the stationary hitch-ends where
multiple roping is used, shall be fastened in such a manner that all portions of the rope except the
portion inside the rope sockets shall be readily visible.
Fastening shall be:
(1) by individual tapered rope sockets or
(2) by other types of rope fastenings, if approved by the enforcing authority, on the basis of adequate
tensile and fatigue tests made by a qualified laboratory provided that:
i. such fastenings conform to the requirements of Rules 212.9b and 212.9c;
ii. the rope socketing shall be such as to develop at least 80% of the ultimate breaking strength
of the strongest rope to be used in such fastenings; and
iii. U-bolt type rope clips (clamps) shall not be used for such fastenings.
(a) Adjustable shackle rods
The car ends, or the car or counterweight dead ends where multiple roping is used, of all
suspension wire ropes of traction type elevators shall be provided with shackle rods of a design
which will permit individual adjustment of the rope lengths. Similar shackle rods shall be
provided on the car or counterweight ends of compensating ropes.
(b) Tapered rope sockets
Tapered rope sockets shall be of a design as shown in Fig. (2.10), and shall conform to the
(1) The axial length L of the tapered portion of the socket shall be not less than 4 3/4 times the
diameter of the rope used.
(2) The axial length L of the open portion of the rope socket shall be not less than 4 times the
diameter of the rope used.
(3) The length of the straight bore L” at the small end of the socket shall be not more than 2 in.
(51 mm) nor less than 1/8 in. (3.3 mm), and its outer edge shall be rounded and free from
abnormal operating conditions: environmental conditions
that are unfavorable, harmful, or detrimental to or for
the operation of a crane, such as excessively high or
low ambient temperatures, exposure to adverseweather,
corrosive fumes, dust-laden or moisture-laden atmospheres,
and hazardous locations.
administrative or regulatory authority: governmental
agency or, in the absence of governmental jurisdiction,
appointed: assigned specific responsibilities by the
employer or the employer’s representative.
authorized: appointed by a duly constituted administrative
or regulatory authority.
auxiliary hoist: supplemental hoisting unit usually of
lower load rating and higher speed than the main hoist.
boom (of gantry cranes): an extension of the trolley runway
that may be raised or retracted to obtain clearance for
boom (of overhead cranes): a horizontal member mounted
on the trolley to permit hoisting and lowering the load
at a point other than directly under the hoist drum or
brake: a device, other than a motor, used for retarding
or stopping motion by friction or power means.
brake, holding: a friction brake for a hoist that is automatically
applied and prevents motion when power to the
brake is off.
brake, mechanical load: an automatic type of friction brake
used for controlling loads in a lowering direction. This
unidirectional device requires torque from the motor to
lower a load but does not impose any additional load
on the motor when lifting a load.
braking means: a method or device used for stopping/
holding motion by friction or power.
braking, control: a method of controlling speed by removing
energy from the moving body or by imparting
energy in the opposite direction.
braking, countertorque (plugging): a method of controlling
speed by reversing the motor line voltage polarity or
phase sequence to develop torque in the direction opposite
the rotation of the motor.
braking, dynamic: a method of controlling speed by using
the motor as a generator, with the energy being dissipated
braking, eddy current: a method of controlling or reducing
speed by means of an electrical induction load brake.
braking, emergency: a method of decelerating a drive
when power is not available. The braking effort may
be established as a result of action by the operator, or
automatically when power to the drive is interrupted.
braking, hydraulic: a method of controlling or reducing
speed by means of displacement of a liquid.
braking, mechanical: a method of controlling or reducing
speed by friction.
braking, pneumatic: a method of controlling or reducing
speed by means of compressed gas.
braking, regenerative: a method of controlling speed in
which the electrical energy generated by the motor is
fed back into the power system.
braking, service: a method to decelerate crane motion
during normal operation.
bridge: that part of a crane consisting of one or more
girders, trucks, end ties, footwalks, and drive mechanism,
which carries the trolley or trolleys.
bridge travel: the crane movement in a direction parallel
to the crane runway.
bumper (buffer): a device for reducing impact when a
moving crane or trolley reaches the end of its permitted
travel, or when two moving cranes or trolleys come
into contact. This device may be attached to the bridge,
trolley, or runway stop.
cab: the operator’s compartment on a crane.
cab, normal: operator’s compartment used for controlling
a cab-operated crane.
cab, skeleton: operator’s compartment used for occasional
cab operation of a normally floor- or remote-operated
cantilever frame: a structural member that supports the
trolley of a wall crane.
clearance: distance from any part of the crane to the
collectors, current: contacting devices for collecting current
from runway or bridge conductors.
conductors, bridge: the electrical conductors located along
the bridge structure of a crane that transmit control signals
and power to the trolley(s).