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COMPUTER AIDED ANALYSIS AND DESIGN OF HOISTING MECHANISM OF AN EOT CRANE

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Int. J. Mech. Eng. & Rob. Res. 2013 Shyam Lal Sharma et al., 2013
COMPUTER AIDED ANALYSIS AND DESIGN OF
HOISTING MECHANISM OF AN EOT CRANE
Shyam Lal Sharma1*, Tasmeem Ahmad Khan1, Md. Parvez1 and Kamlesh Kumari2
*Corresponding Author: Shyam Lal Sharma, shyambash2009@yahoo.in
In this project an overall design the hoists generally confirm to IS: 3177 of the hoisting mechanism
of an EOT crane has been carried out. The dimensions of the main components have been
determined for a load capacity of 50 ton crane having 8 rope falls. Various dimensions for cross
sections of various shapes for crane have been found. After the system was designed, the
stress and deflection are calculated at critical points using ANSYS and optimized. Which cross
section would be better keeping some parameters constant for all the case .Various dimensions
and load per wire for wire ropes has been found. Using various formulae found the dimensions
for pulley, Rope-drum. Also calculated the Power and ratings for the motor brakes used in the
hoist mechanism.
Keywords: Single girder electrical overhead traveling crane in cross travel and long travel,
Hoisting mechanism, No. of falls, Computer aided design, ANSYS and optimization,
Pulley, Rope-drum, Hook block, Motor brakes
HISTORY OF CRANES
The cranes have found many uses since the
beginning of the history, and the history of
cranes has come across since then. The Greek
were the first people to use cranes for doing
the lifting jobs. After this many other peoples
like the Roman, the Chinese, etc., used the
cranes and made many changes to the existing
design of that time.
ISSN 2278 – 0149 www.ijmerr.com
Vol. 2, No. 3, July 2013
© 2013 IJMERR. All Rights Reserved
Int. J. Mech. Eng. & Rob. Res. 2013
1Department of Mechanical Engineering, Al Falah School of Engineering and Technology, Fbd, Hr.
2Mechanical Design Engineer, Desein & Indure Pvt. Limited, New Delhi
METHODOLOGY
Hoisting is the process of lifting something or
some load from lower position to higher
position with the help of some device or
mechanism.
The Electric Overhead Traveling Crane
consists essentially of a girder, or girders,
supported at each end on tracks capable of
traveling on elevated fixed tracks. And a trolley,
Research Paper
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Int. J. Mech. Eng. & Rob. Res. 2013 Shyam Lal Sharma et al., 2013
equ ipp ed wit h ho is t in g an d oth e r
mechanism, capable of traversing from end
to end of such girder or girders. Such cranes
vary in lifting capacity from about 2 tons to
400 tons, and in span from 20 ft. to 150 ft, or
more. For capacities of 10 tons and upwards
an independent auxiliary hoist rated at 1/5
to 1/3 that of the main hoist is frequently
provided. The c omputer Aided Design
facilitates gives alternative parameters and
thus calculates the unknown parameter
which speeds up the design process. In the
computerization the scope for providing
cabins fixed to bridge is eliminated thus
reducing the cost and and space.
Computer A id ed Design of Ele c t ri c
Overhead Traveling Crane employs Visual
Basic as the front end. In the design using
Visual Basic, the user will have to input, the
Load to be lifted, the operating conditions as
in nature of duty, service factors, hoisting
speed and then the design of rope is done.
The Design of rope is on the basis of life criteria
and can be checked for strength criteria and
vice versa based upon the data available. The
diameter of rope is calculated and the thus the
diameter of sheave is calculated. During
calculation of rope diameter the tackle
efficiency, fall system depending on load, lay
of rope and thus various parameters are
analyzed for selecting the diameter of rope. In
the tackle assembly the moving sheave
assembly and hook Assembly are calculated.
In case of Moving sheave assembly the
diameter of moving sheaves an d
corresponding dimensions of sheave is
calculated. Similarly the selection of bearings,
dimensions of shackle plate and check plate
are calculated. In case of hook assembly the
bed diameter is decided based on load and
then the corresponding dimensions are
generated by empirical relations and thus all
the dimensions are obtained. Then failure
analysis is carried at every part. For example
when the tensile failure at the threaded part is
carried out in case of failure the dimensions
are rectified thus modifying the load and the
overall dimensions. Thrust bearing design is
followed and the bearing selection is
completed. Finally the cross-piece design is
carried out taking into account the various
design considerat i o ns . Th e hoi s t i ng
mechanism is designed by selection of
appropriate drive unit and rope drum.
MECHANICS AND
OPERATION
In contrast to modern cranes, medieval cranes
and hoists-much like their counterparts in
Greece and Rome—were primarily capable
of a vertical lift, and not used to move loads for
a considerable distance horizontally as well.
Accordingly, lifting work was organized at
the workplace in a different way than today. In
building construction, for example, it is
assumed that the crane lifted the stonne blocks
either from the bottom directly into place or
from a place opposite the centre of the wall
from where it could deliver the blocks for two
teams working at each end of the wall.
Additionally, the crane master who usually
gave orders at the tread wheel workers from
outside the crane was able to manipulate the
movement laterally by a small rope attached
to the load. Slewing cranes which allowed a
rotation of the load and were thus particularly
suited for dockside work appeared as early
as 1340.
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Int. J. Mech. Eng. & Rob. Res. 2013 Shyam Lal Sharma et al., 2013
While ashlar blocks were directly lifted by
sling, Lewis or devil’s cla mp (German
Teufelskralle), other objects were placed
before in conta i n ers li ke pa l l et s,
baskets,wooden boxes or barrels.
It is noteworthy that medieval cranes rarely
featured ratchets or brakes to forestall the load
from running backward. This curious absence
is explained by the high friction force exercised
by medieval tread wheels which normally
prevented the wheel from accelerating beyond
control.
LITERATURE SURVEY
Rajendra Parmanik in a post Design of
Hoisting Arrangement of Electric Overhead
Traveling Crane (2008) has discussed about
history of crane, various types of crane
,application and a model design of the various
parts of the EOT crane R Uddanwadiker, in
the paper “Stress Analysis of Crane Hook and
Validation by Photo-Elasticity” states that
“Crane Hooks are highly liable components
and are always subjected to failure due to
accumulation of large amount of stresses
which can eventually lead to its failure by
predicting the stress concentration area, the
shape of the crane is modified to increase its
working life and reduce the failure rates.”
Single Girder EOT Crane diagram includes
Single Girder, Bus Bar, Hoist for lifting
something or some load from lower position
to higher position with the help of some device
or mechanism.
PLAN OF ACTION
In the designed hoist model trapezoidal
section show less stress. The modified section
should show less stress but due to reduction
in area it shows more stress. Using more no.
of rope falls divide the load and make the
tension less. Also it makes the work faster.
E.g., if we use 4 rope falls then using the same
force 4 times work is done. But increase in
rope fall increase the rope length by that times,
which is expensive also the rope lengths
determine the drum length. Increase in drum
length increase the volume of setup to reduce
the volume we can double winding of rope on
the drum can be adopted. Motor power
required depends on lifting speed and load
applied. The angular speed of drum and the
motor are different so a gear box is used for
power transmission. Performing number of
experiment on principle of bending of a beam
with large initial curvature
Algebraic calculations
Empirical calculations
3D modeling Software
ANSYS for stre s s calculatio n and
deformation analysis
CRANE AND HOIST SAFETY
DESIGN REQUIREMENTS
The following are the design requirements for
cranes and hoists and their components:
Figure 1: Diagram of Single Girder EOT
Crane (Hoist Mechanism)
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Int. J. Mech. Eng. & Rob. Res. 2013 Shyam Lal Sharma et al., 2013
The design of all commercial cranes and
hoists shall comply with the requirements
of ASME/ANSI B30 standards and Crane
Manufacturer’s Association of America
standards (CMAA-70 and CMAA-74).
All crane and hoist hooks shall have safety
latches.
Hooks shall not be painted (or re-painted)
if the paint previously applied by the
manufacturer is worn.
Crane pendants shall have an electrical
disconnect switch or button to open the
main-line control circuit.
Cranes and hoists shall have a main
electrical disconnect switch. This switch
shall be in a separate box that is labelled
with lockout capability.
Crane bridges and hoist monorails shall be
labelled on both sides with the maximum
capacity.
Each hoist-hook block shall be labelled with
the maximum hook capacity.
Directional signs indicating N-W-S-E shall
be displayed on the bridge underside, and
a corresponding directional label shall be
placed on the pendant.
A device such as an upper-limit switch or
slip clutch shall be installed on all building
cranes and hoists. A lower-limit switch may
be required when there is insufficient hoist
rope on the drum to reach the lowest point.
All newly installed cranes and hoists, or
those that have been extensively repaired
or rebuilt structurally, shall be load tested at
125% capacity prior to being placed into
service.
If an overload device is installed, a load test
to the adjusted setting is required.
Personnel baskets and p l at forms
suspended from any crane shall be
designed in a cc o rd ance with the
specifications in 29 CFR 1926.550 (g) and
COMAR 09.12.38.
All cranes used for personnel lifting, shall
have anti-two blocking devices installed and
operational.
Cranes taken out of service, for extended
periods, shall be clearly tagged/labeled “Out
of Service;” OOS labels shall be signed and
dated. Cranes that are out of service shall
have the power physically disconnected or
locked out.
CRANE AND HOIST
OPERATION RULES
Pre-Operational Test
At the start of each work shift (on a day when
the crane and/or hoist will be used), operators
shall do the following steps before making lifts
with any crane or hoist:
Test the upper-limit switch. Slowly raise the
unloaded hook block until the limit switch
trips.
Visually inspect the hook, load lines, trolley,
and bridge as much as possible from the
operator’s station; in most instances, this
will be the floor of the building.
If provided, test the lower-limit switch.
Test all direction and speed controls for both
bridge and trolley travel.
Test all bridge and trolley limit switches,
where provided, if operation will bring the
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equipment in close proximity to the limit
switches.
Test the pendant emergency stop.
Test the hoist brake to verify there is no drift
without a load.
If provided, test the bridge movement
alarm.
Lock out and tag for repair any crane or
hoist that fails any of the above tests. Do
not return to service until necessary
maintenance is completed.
Moving a Load
Center the hook over the load to keep the
cables from slipping out of the drum
grooves and overlapping, and to prevent the
load from swinging when it is lifted. Inspect
the drum to verify that the cable is in the
grooves.
Use a tag line when loads must traverse long
distances or must otherwise be controlled.
Manila rope may be used for tag lines.
Plan and check the travel path to avoid
personnel and obstructions.
Lift the load only high enough to clear the
tallest obstruction in the travel path.
Start and stop slowly.
Land the load when the move is finished.
Choose a safe landing.
Never leave suspended loads unattended.
In an emergency where the crane or hoist
has become inoperative, if a load must be
left suspended, barricade and post signs
in the surrounding area, under the load, and
on all four sides. Lock open and tag the
crane or hoist’s main electrical disconnect
switch.
Parking a Crane or Hoist
Remove all slings and accessories from the
hook. Return the rigging device to the
designated storage racks.
Raise the hook at least 2.1 m (7 ft) above
the floor.
Store the pendant away from aisles and
work areas, or raise it at least 2.1 m (7 ft)
above the floor.
Place the emergency stop switch (or push
button) in the OFF position.
GENERAL RIGGING SAFETY
REQUIREMENTS
Use only select rigging equipment that is in
good condition. All rigging equipment shall be
in spected at le a st annually. Defective
equipment shall be removed from service and
destroyed to prevent inadvertent reuse. The
load capacity limits shall be stamped or affixed
to all rigging components. Prudent practice
requires a minimum safety factor of 5 to be
maintained for wire rope slings.
The following types of slings shall be
rejected or destroyed:
Nylon Slings with
Abnormal wear.
Torn stitching.
Broken or cut fibers.
Discoloration or deterioration.
Wire-Rope Slings with
Kinking, crushing, bird-caging, or other
distortions.
Evidence of heat damage.
Cracks, de formation , o r wo r n e nd
attachments.
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Int. J. Mech. Eng. & Rob. Res. 2013 Shyam Lal Sharma et al., 2013
Six randomly broken wires in a single rope
lay.
Three broken wires in one strand of rope.
Hooks opened more than 15% at the throat.
Hooks twisted sideways more than 10
degrees from the plane of the unbent hook.
Alloy Steel Chain Slings with
Cracked, bent, or elongated links or
components.
Cracked hooks.
Shackles, eye bolts, turnbuckles, or other
components that are damaged or deformed.
Rigging a Load
Operators shall do the following when rigging
a load:
Determine the weight of the load. Do not
guess.
Determine the proper size for slings and
components.
Do not use manila rope for rigging.
Make sure th a t sha c k le pi n s an d
shouldered eye bolts are installed in
accordance with the manuf acturer ’s
recommendations.
Make sure that ordinary (shoulder less) eye
bolts are threaded in at least 1.5 times the
bolt diameter (Grade 8 preferred).
Use safety hoist rings (swivel eyes) as a
preferred substitute for eye bolts wherever
possible.
Pad sharp ed ges to pr o te c t sli n gs .
Remember that machinery foundations or
angle-iron edges may not feel sharp to the
touch but will cut into rigging when under
several tons of load. Wood, tire rubber, or
other pliable materials may be suitable for
padding.
Do not use slings, eye bolts, shackles, or
hooks that have been cut, welded, brazed,
or otherwise altered.
Install wire-rope clips with the base only on
the live end and the U-bolt only on the dead
end.
Follow the manuf a c turer s
recommendations for the spacing for each
specific wire size.
Determine the center of gravity and balance
the load before moving it.
Initially lift the load only a few inches to test
the rigging and balance.
APPLICATIONS
The most common Electric Overhead
Traveling Crane use is in the steel industry.
At every step of the manufacturing process,
until it leaves a factory as a finished product,
steel is handled by an overhead crane. Raw
materials are poured into a furnace by crane,
hot steel is stored for cooling by an overhead
crane, the finished coils are lifted and loaded
onto trucks and trains by overhead crane,
an d the fa bricator or stamper uses an
Electric Overhead Traveling Crane to handle
the steel in his factory. The automobile
industry uses overhead cranes for handling
of raw materials. Smaller workstation cranes
handle lighter loads in a work-area, such
as CNC mill or saw.
Almost all paper mills use bridge cranes for
regular maintenance requiring removal of
heavy press rolls and other equipment. The
bridge cranes are used i n th e in i t ia l
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Int. J. Mech. Eng. & Rob. Res. 2013 Shyam Lal Sharma et al., 2013
construction of paper machines because they
facilitate installation of the heavy cast iron
paper drying drums and other massive
equipment, some weighing as much as
70 tons.
In many instances the cost of a bridge crane
can be largely offset with savings from not
renting mobile cranes in the construction of a
facility that uses a lot of heavy process
equipment.
CONCLUSION
In the designed hoist model trapezoidal
section show less stress.
The modified section should show less
stress but due to reduction in area it shows
more stress.
Using more no. of rope falls divide the load
and make the tension less. Also it makes
the work faster. E.g., if we use 4 rope falls
then using the same force 4 times work is
done.
But increase in rope fall increase the rope
length by that times, which is expensive.
Also the rope lengths determine the drum
length.
Increase in drum length increase the volume
of setup to reduce the volume we can
double winding of rope on the drum can be
adopted Motor power required depends on
lifting speed and load applied.
The angular speed of drum and the motor
are different so a gear box is used for power
transmission.
REFERENCES
1. http://www.codecogs.com/reference/
engineering/materials/curved_beams.
php (Updated Last on 2011).
2. Rajendra Parmanik (2008), “Design of
Hoisting Arrangement of E.O.T. Crane”,
Posted on July 26, available at http://
rparmanik.wordpress.com/about-me-
rajendra-parmanik
3. Shariff Abdulla (2009), “Hand Book of
Properties of Engineering Materials Ans
Design Data for Machine Elements”.
4. www.wikipedia.org
... This new design method is applied to the design case of gantry cranes so that it improves the variant design efficiency and reduces the design cost. Sharma et al. (2013) worked on the design of the hoisting mechanism of an EOT crane using IS:3177. The dimensions of the main components are determined after the system is designed. ...
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This review paper gives the discrimination of various failure analysis accomplish to find Crane hook, Rope, Rope Drum, Coupling, Gear and Motor Shaft failure. These are very significant parts of EOT crane used for lifting, lowering and move with the help of links or rope and highly liable component which are always subjected to failure due to amount of stress, dynamic and statistic load concentrations which can lead to its failure. To minimize the failure of different part of EOT Crane by Using safe design with appropriate manufacturing processes and obstructive mechanical maintenance techniques. Failure of any parts of crane causes the unneeded shutdown and its lead to heavy loss. The main aim of this paper is to study various component of EOT crane failure analysis and finding out root cause failure of different parts of crane. Through this paper various literature have been comprehensively compared to get Crane hook, Rope, Rope Drum, Coupling, Gear and Motor Shaft failure analysis. Keywords: Crane hook, Rope, Rope Drum, Coupling, Gear and Motor Shaft, Stress, EOT Crane, techniques, etc.
Hand Book of Properties of Engineering Materials Ans Design Data for Machine Elements
  • Shariff Abdulla
Shariff Abdulla (2009), "Hand Book of Properties of Engineering Materials Ans Design Data for Machine Elements".