This document discusses the diagnosis and rectification of tracking problems in bridge cranes. It begins by describing common symptoms of tracking issues like frequent wheel replacements and broken tie-backs. It then provides a simplified description of how skewing occurs due to differences in traction between the driven ends of the bridge. The rest of the document outlines six troubleshooting procedures for identifying potential causes of tracking problems related to the runway, wheels, bridge frame alignment, bridge mechanics, motor drives, and runway/building structure. It concludes by describing a specific case of rectifying rail bar span issues on a 10MT EOT crane to address problems with the crane stopping in certain locations.

1. DEEEPAK KUMAR SAHOO Page 1
SUBMITTED TO
NALCO(M&R),DAMANJODI
SUBMITTEDBY
Mr.DEEPAKKUMARSAHOO
YEAR-2015-2016

2. DEEEPAK KUMAR SAHOO Page 2
DIAGNOSIS & RECTIFICATION OF BRIDGE (EOT) CRANES
TRACKING PROBLEMS
Introduction
Poor bridge tracking can be a major and expensive maintenance problem for
overhead cranes. It is also one of the most critical problems to troubleshoot.
Tracking problems are difficult to diagnose because of the many conditions that
cause them. If they are not pro-actively rectified, the destructive action feeds on
itself and problems can multiply. When this happens, the problem becomes even
more complicated.
Symptoms
For abnormal tracking behavior, the following are some of the symptoms:
 Frequent replacement of wheels, wheel bearings, and rails.
 Broken tie‐backs between runway beams and columns.
 Extra drive power required to muscle through certain areas of the runway.
 Broken wheel flanges.
 Loud scraping sounds.
 Wheel flanges pressed hard against the rail head.
 End trucks cracked near the wheel assemblies.
 Loose girder connections.
 Wheel flanges attempt to climb over the rail then suddenly crash down.
 Bridge derailment.
Skewing, side thrust, and wheel/rail wear occur naturally during bridge tracking.
Design specifications for cranes and runways provide for lateral crane loads and
forces caused by steering and skewing.

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A Simplified Description of Skewing
Skewing occurs when there is a difference in traction or speed between the driven ends of the
bridge. For this description we will assume that skewing is initiated by one drive end moving
faster than the other, or from drive wheel skidding/slippage.
Wheel float
Figure 1:-Crane wheel floating

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When this happens, the following events are set into motion:
I. The drive effectively delivers a larger traction force to one end of the bridge.
II. The difference in traction between the driven ends causes the bridge span to act as a
lever arm.
III. The lever arm forces are resisted by lateral loading of the wheels and rail.
IV. The lever‐arm action causes the bridge frame to temporarily deform
V. The deformation causes the corners of the bridge frame to twist, and the wheels to
VI. become temporarily misaligned. If the frame is not stiff enough, the misalignment will
contribute to the tracking problem.
VII. The frame will remain deformed as long as there is a difference in traction force
between the driven ends.
VIII. The traction difference causes the crane to steer to one side of the runway.
IX. The crane will continue to steer to one side until the wheel flange touches the side of
the rail head.
X. The wheel flange applies a lateral force to the runway.
XI. The lateral force creates a friction force parallel to the runway.
XII. The friction force counteracts the traction force.
XIII. The random differences of the friction forces between bridge ends causes the skew
angle to intermittently increase and decrease.
XIV. See Figure 2. The crane rotates (in plan) until the cumulative effect of wheel flange
contact and lateral friction are equal to the effect of the traction force difference
between the driven ends. The angle of rotation is the skew angle.
XV. If the skew angle is allowed to be large enough, the friction force parallel to the runway
will equal or exceed the traction force and the crane will bind and come to a halt.
XVI. If the drives have sufficient power and traction, the wheels will climb up the rail and the
crane may derail.
XVII. If the skew angle is prevented from being large, the flange will skip off the side of rail
and continue tracking along the runway path.

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Six Troubleshooting Procedure for EOT crane Tracking Problems
Runway
Rail‐Related
Wheel‐Related
Bridge Frame
Alignment
Bridge
Mechanical‐Re
lated
Motor
Drive‐Related
Runway &
Building
Structure‐Relat
ed

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RUNWAY RAIL RELATED
Condition Cause How to Detect Corrective Action
1 Runway rails out of
horizontal alignment.
Misaligned rails cause
wheels to bind.
Perform a runway
alignment survey
Align rails
2 Excessive wheel float
caused by rail wear.
float allows a larger
skew angle, larger
lateral rail force, and
binding.
Inspect sides of rail
head for excessive
wear.
Replace worn rails.
3 Excessive lateral rail
movement caused by
use of floating rail
clamps.
Floating clamps allow
rail to shift laterally,
causing a larger skew
angle.
Check for gaps
between rail base and
rail clamp. Clamps
should be tight against
both edges of rail
base.
Replace floating rail
clamps with
non‐floating type
clamps or clips.
4 Drive wheel skidding
or slippage.
Causes unbalanced
traction between drive
wheels resulting in
skewing.
Inspect rail surfaces
for liquid or debris.
Keep rails clean and
dry. Adjust motor
controls to reduce
acceleration.
5 Runway rail elevation
out of alignment.
Relatively large
elevation differences
are required to cause
problems.
Perform a runway
alignment survey.
Align rails per
tolerances.
RUNWAY & BUILDING STRUCTURE‐RELATED
Condition Cause How to Detect Corrective Action
1 Broken tie‐backs for
runway beams
Causes rail
misalignment
Visual structural
inspection.
replace tiebacks
with improved
design.
2 Long span runway
beam on one side of
the runway.
Longer beam spans
have larger deflection.
See note below
Observe poor tracking
behavior over bays
where one end of the
bridge is supported by
a beam with a
significantly
longer span than the
other end.
Specify positive
camber and increased
stiffness for the long
span beam.
3 Excessive deflection of
runway beam support
Columns are
eccentrically loaded by
Poor tracking at or
near columns
increase the
column stiffness

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brackets on columns. cantilevered support
brackets for runway
beams, causing the
runway to deflect and
decrease the runway
span.
4 Wind load on exterior
wall causes excessive
lateral deflection of
runway.
If the runway is
adjacent to an exterior
wall, wind
loading may cause
runway lateral
deflection. More
significant for tall
structures.
Poor tracking behavior
during windy
conditions.
increase
lateral stiffness at the
elevation of the
runway.
Notes:
When the bridge travels across the runway beam, it deflects downward and assumes a concave shape. The
bridge then travels on a downward slope until it reaches the mid span of the beam. After passing the mid span,
the bridge travels uphill. More power is required for travelling uphill, and less for downhill. This condition
creates a difference in traction force between the driven ends and can cause skewing.
MOTOR DRIVE RELATED
Condition Causes How to Detect Corrective Action
1 Difference in braking
torque between drive
wheels.
Applies to
independent
drives with magnetic
control. One end of
the bridge stops faster
causing skewing.
Visual observation of
one end of the bridge
stopping before the
other.
Adjust brake torque
settings to obtain
equal torque.
2 Drive motor speeds
not
equal.
Applies to
independent
drives with magnetic
control. One end of
the bridge travels
faster causing skewing.
Monitor motor speeds
under dynamic
conditions
Service motors and/or
motor controls to
obtain
synchronized motor
speeds

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BRIDGE MECHANICAL‐RELATED
Condition Causes How to Detect Corrective Action
1 Drive shaft too flexible Applies to cross‐shaft
connected drive
wheels. Flexible
shafting causes a
larger difference in
angular twist between
drive wheels.
Perform an
engineering
analysis to confirm
that angular deflection
of
shafting is within
allowable limits
Replace with larger
diameter shafting
for allowable shaft
twist.
2 Drive shaft couplings
loose or worn.
Causes drive wheels to
be unsynchronized.
Inspect bridge drive
couplings
Replace loose or worn
couplings.
3 Drive shafts become
preloaded,
shaft windup is
locked‐in.
Applies to cross‐shaft
connected drive
wheels where
4‐wheels are driven. If
one drive wheel slips
relative to the others,
the drive
shafts can become
preloaded with
torsion.
Observe tracking and
watch for wheel
skidding or slippage
Inspect rail surfaces
for liquid or debris.
Keep rails clean and
dry. Jack the drive
wheel off the rail to
release the torque.
BRIDGE FRAME ALIGNMENT
Condition Causes How to Detect Corrective Action
1 Bridge trucks, bogie
trucks, or end ties out
of alignment.
Original equipment
may be misaligned, or
became misaligned
from other causes.
Complete a precise
wheel alignment
survey.
"MCB" bearing
capsules can be
shimmed for
alignment.
2 Bridge span dimension
out of tolerance
relative
to runway rail span.
Has same effect as rail
span misalignment.
Use a precise laser
"distance meter" to
measure the bridge
wheel spans.
Consult with a
qualified person for
bridge span
modifications.
3 Loose girder
connections.
Allows bridge frame to
become misaligned.
Inspect girder
connections.
Complete a precise
wheel alignment
survey. Ream holes to
next larger bolt
diameter, use
interference fit bolts.
4 Bridge acceleration or
deceleration with
trolley at or near one
end of the bridge
One end of
bridge moves faster
than the other causing
skewing.
Observe tracking
behavior during
acceleration with
trolley at center of
Modify duty cycle so
that bridge
acceleration does
not start until trolley is

9. DEEEPAK KUMAR SAHOO Page 9
span compared to
acceleration with
trolley at end of
bridge.
near mid span of
bridge.
5 End trucks or end ties
too flexible.
Frame deformation
can cause temporary
wheel misalignment
and skewing.
Perform an
engineering analysis to
determine corner
rotation under normal
service loads.
Consult with a
qualified person to
increase the stiffness
of the bridge frame.
WHEEL RELATED
Condition Causes How to Detect Corrective Action
1 Wheel misalignment
relative to other
wheels and tracking
direction
Produces the same
effect as rail
misalignment, and
causes skewing.
Complete a precise
wheel alignment
survey.
"MCB" bearing
capsules can be
shimmed for
alignment.
2 Excessive wheel float
caused by wheel
flange wear.
Excessive float allows a
larger skew angle,
larger lateral rail
force, and binding.
Inspect wheel flanges
for excessive wear.
Use greater flange
hardness for
replacement wheels.
3 Drive wheel diameters
not matched within
tolerance.
Causes speed
difference across the
span, resulting
in skewing.
Check wheel tread
Diameters &
tolerances.
Replace drive wheels
with wheel pairs that
have matching
diameters within
recommended
tolerance.
4 Excessive wear of drive
wheel tread
Creates variable drive
tread circumference
and
causes a speed
difference between
drive wheels.
By visual examination.
Normal tread surfaces
should look perfectly
flat.
Replace worn wheels,
use greater tread
hardness
5 Excessive wheel float
due to tread profile
too wide for rail head.
Excessive float allows a
larger skew angle,
larger lateral rail
force, and binding.
Float should be within
the values shown
Replace with wheels
that have proper tread
width.
6 Wheel bearing failure. Causes skewing due to
rolling resistance at
one end of the bridge.
High local temperature
at the bearing capsule,
paint discoloration,
noise.
Replace bearing and
capsule.

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Description:- Correction of EOT Crane tracking problem.
RAIL BAR SPAN CORRECTION OF EOT CRANE
SL.NO. Details Specification
1 Crane 28-HH-ET-1301
2 Capacity(MT) 10
3 Make Oswal Machinery
4 Location Compressor House
1. Checking square rail bar span at every three meters interval using measuring tape.
Pre Observation & Analysis of works:-
2. Checking rail bar alignment –straightness at every three meters using nylon thread.
3. Checking rail bar level-parallel at every three meter using water tube test.
4. Visual inspection of condition of gantry rail bar, its wear and condition of rail bar joints.
1. Rectification of gantry rail bar span to bring it within permissible limits and to match with
crane span.
Procedure Of Rail Bar Alignment for Span:
2. Rectification of gantry rail bar level difference between two rails at the same location and
to bring it within 10 mm.
3. Rectification of gantry rail bar straightness to bring it within ±10 mm.
4. Rectification of rail bar gradient to bring it within working limits.
5. Removal of rails bars for rectification like facing of rails, maintaining span and level of gantry
Rail bar for LT motion of the crane.
6. Cleaning & preparation of surface by grinding etc. so that rail can be placed firmly onto the
Surface directly or placement of packing plates (for level maintaining) after proper surface
preparation.
7. Welding to be done at intermittent distance to fix the rail bar on the gantry.
8. Alignment of center distance between rail bar lines at equal intervals using measuring
tape or Laser instrument.
9. The work alignment should be carried out confirming to relevant clauses of IS:3443 for
works like removal of welded joints, cutting of damaged rail bar and fixing new bars.
10. Alignment of height and level of each rail bar at equal interval using water level
tube test or laser instrument(tolerance within +/-5mm in every one meter length).

11. DEEEPAK KUMAR SAHOO Page 11
(Compressor & utility Area)
RAIL SPAN CORRECTION OF EOT CRANE
Pre observation of rail bar span problems:
During long travel the 10MT Capacity EOT crane did not run smoothly and sometimes at
particular location(i.e isolator switch side and also at platform side ).
 it stopped while the motors and other parts are in function.
This problems occured due to rail span dimensional error.
a) The square rail bar required dimension is 50*50mm but at isolator side 10mts
length(Dsl side-6.2mtr,Nondsl Side-3.76mtr) rail found 60*60mm which was not in
acceptable condition for free wheel running of EOT crane.
b)At the joints the wheel did not move forward due sudden change of rail dimension.
c)After measuring the rail span it is found that the rail span also varies at that place due to
incorrect alignment of rails.
c)To rectify the problems the span should be corrected with proper square bar rail using.
50mm 60mm
Fig:-TOP VIEW OF SQUARE BAR RAILS
50mm
60mm
wheel
wheel

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According to the causes plan the procedure with better engineering techniques so that
the problem will be corrected.
PLAN & PROCEDURE
The following things to be planed before start a maintenance work:
• TIME
• COST
• MANPOWER
• TOOLS
• EQUIPMENTS
• TECHNOLOGY
The rectified rail bar span work requirement detail
TIME
s:-
COST MANPOWER TOOLS or
EQUIPMENTS
TECHN
OLOGY
REMARK
S
3DAYS=24Ho
ur(3*8)
1.21-DEC-2015
2.22-DEC-2015
3.28-DEC-2015
18741.60
According to
work
measurement
clause-486 of
C & H
Maintenance
TOTAL=7
INCLUDING COMPANY
ENGINEER
1. Supervisor=1
2. Fitter=2
3. Welder/grinder/c
utter=2
4. Helper=1
1. GAS CUTTING
MACHINE.
2. Welding
machine
3. Grinding
machine
4. Maintenance
hand tools
5. Measuring
tools
As per
engineer
ing
designin
g
standar
d
IS: 3443

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PROCESS & PROCEDURE FOR RAIL BAR ALIGNMENT
DETECTING DEFECTS
GAS CUTTING OF DEFECTS
GRINDING FOR REMOVING MOLTEN METAL
ALIGNMENT OF NEW BARS
MEASUREMENT
WELDING
GRINDING FOR SURFACE FINISH
CONFORM MEASUREMENTS

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1.Gas cutting of the defected square bar
Methods
This indicated portion is require to for cutting and replacing a new one.
Note**The gas cutting should be done perfectly so that the base plate will not damage.
GAS CUTTING OF
UNWANTED BAR
DEFECT ON
RAILS

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After cutting and removing the rail by gas cutting some melted metal will stick to the base plate
for that the grinding is done to remove this waste metals.
2.GRINDING :-
Melted
metals on
base plate

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**NOTE**-The surface should be grinded carefully over grinding avoided to maintain surface finish.
Grinding of
base plate
SURFACES
AFTER
GRINDING

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3.ALIGNMENT ARRANGEMENT
• Marking straight line:-
At first take the span length and mark at different points. Referring to these points make a
straight thread line.
Marking line obtain by using nylon thread and marker .
Marking by
nylon
thread

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• Then put the new rail in position and weld them in two ends.
• For correct alignment the following arrangements may be use.
C-clamp are used to protest the movement of rail and to reduce the gap between rail and base
plate during alignment ,L-clamp are also used for same purposes.
C- CLAMP
NEW BAR
OLD BAR

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Fig:-C-clamp arrangement for alignment of rail
• L-clamp are used to correct the slide twisting of rail during erection.
L-CLAMP & End side stopper
• Where as end side stopper are used to protect the movement of rail either two side.
• Packing are used in C-Clamp & L-Clamp to reduce the gap between base plate and rails.
c-clamp plate
arrangement

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Fig:-Rail alignment
WELDING :-
 After alignment of rail welding is to be done at different places with specific distance
to fix the rail on the base plate.
 All temporary c-clamp ,l-clamp & end side stoppers removed after welding done.
 Grinding should be done at joints and rough surfaces of the rail bars for surface
finish.
 Measurement of the rail span should be done again to confirm the correction.
L-CLAMP
PACKING
C-CLAMP
SQUARE
BAR RAIL
SIDE
STOPER

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Fig:-Surface finishing by grinding
Grinding or
surface finishing

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Measurement report of crane span correction
EQUIPMENT
NO.
SWL CRANE
SPAN(mm)
RAIL SPAN BEFORE
RECTIFICATION(mm)
RAIL SPAN AFTER
RECTIFICATION
REMARS/WORKS
28-HH-ET-
1301
10MT a)11500(non
drive side)
b)11500(drive
side)
 11490
 11490
 11490
 11510*
 11500*
 11510*
 11500*
 11500
 11500
 11490
 11490
 11515*
 11515*
 11515*
 11490
 11490
 11490
 11500*
 11500*
 11500*
 11500*
 11490
 11490
 11490
 11490
 11500*
 11500*
 11500*
1.The bending
portion of square
bar is shifted and
straighten about
10mm to avoid
flange crossing
with rail bars.
2.60*60mm bar is
changed by
replacing50*50mm
bar about 6mtr
length which
reduce rail span
15mm .
The crane is moving smoothly with functional load of 2MT without any
obstruction after the crane rail bar span rectified which will increase the
reliability of the running wheel as well as the safety of crane but the pro active
preventive maintenance should be carried out for better equipment life.
CONCLUSION

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