Coupling Alignment

COUPLING ALIGNMENT

1. COUPLING AND
ALIGNMENT.

2. COUPLING is the device used to join two shafts
say, the Driver and the Driven to transmit power.
Functions of Shaft Couplings
To provide connection and Disconnection
between the driver & follower.
To provide Alignment facilities.
To allow flexibility between shafts.
To reduce transmission of SHOCK loads.
To introduce protection against overloads.
To alter vibration characteristics of rotating
units.

3. Requirements of a good Shaft Couplings
1. It should be easy to connect and dis-
connect.
2. Should be able to transmit full power.
3. Should hold shaft in alignment.
4. Should be able to reduce the shock
loads.
5. Should have no projecting parts.
6. Should have smooth surfaces.

4. FLANGE
SLEEVE
MUFF
COUPLINGS
RIGID FLEXIBLE
KNUCKLE
OLDHAM
METALIC NON-METALIC
GRID
CHAIN
GEAR
PAD
BUSH
TYRE
SPIDER

8. Pin & bush Flexible coupling.

9. Pin & bush Flexible coupling.

10. Pin & bush Flexible coupling.

11. Steel Grid or BB coupling.

12. TYRE COUPLING.

13. GEAR COUPLING.

14. Material for Flexible elements.
STEEL.
PLAIN RUBBER.
SYNTHETIC RUBBER.
LEATHER.
TEFLON.
PLASTIC.

15. a) REMOVAL.
a)Never remove by hammer blow.
b)Use conventional pullers.
c)Hydraulic jack can be used.
d)If needed, removal by heating can
be done, but with great care not to
damage the shaft.

16. b) REFITTING.
a) Clean Shaft surface & Coupling bore.
b) Measure the bore & shaft OD to check tolerance.
c) Do not use a coupling if it has any cracks.
d) Always change coupling in pairs.
e) Check coupling OD for trueness & out of
roundness.
f) If high interference fit is needed, couplings can be
heated in an oil bath up to 120°C.
g) Check Key & Keyway for proper fit.
h) Use pushers for fitting. DO NOT HAMMER.
i) Fit coupling face perpendicular to the shaft axis.

17. PROBLEMS IN COUPLINGS
Crack on couplings.
Couplings loose on shaft.
Holes becoming oval.
Coupling edge damage.
Key & Keyway damage.
Both coupling halves not equal in OD.

18. HYDRAULIC COUPLING
A hydraulic coupling consists of two identical halves,
one fixed to the driving shaft A and the other to the
driven shaft.B Both these halves are housed in a
common casing, filled with oil.which is used as a
working medium. A is in the form of pump impeller and
B is in the form of a turbine runner.
When A rotates, oil is forced out through the
periphery of the pump impeller. The oil enters
the turbine runner and makes it to rotate. In
actual practice, the speed of B is less than that of
A by 2 to 4 %
Efficiency ή= Pb/Pa = Nb/Na
Slip s = 1 –ή= 1 –Nb/Na

19. Hydraulic Coupling
A
B

20. Hydraulic Torque Converter
A hydraulic torque converter is an improved
form of hydraulic coupling. In this, the Torque
( or Speed) of the driven shaft may be increased
o0r decreased. It is achieved by providing a
third member in between the pump impeller
and the turbinrrunner, known as guide ring. It
consists of a series of fixed guide vanes, whose
function is to change the direction of oil, which
multiplies the speed of the runner.

21. ALIGNMENT.
Alignment is the adjustment of relative position of
2 coupled machines, so that the centre line of the
axis will be concentric when the machines are
running during NORMAL WORKING
CONDITIONS.
Misalignment may be :-
PARALLEL.
ANGULAR.
COMBINED PARALLEL & ANGULAR .

23. Consequences of misalignment.
A) Reduction in bearing life.
B) Coupling degradation.
C) Shaft fracture.
D) Vibration.
E) Other rotating part failures.

24. CHECKS BEFORE STARTING
ALIGNMENT.
Coupling gap.
Soft foot.
Indicator sag.
Dial indicator rigidity.
Alignment readings. (0°, 90°, 180°& 270°)
Thermal growth. (Steel-0.01mm/M for
1°C rise in temperature.)
Sleeve bearing offset.

25. ALIGNMENT :SOFT FOOT
SOFT FOOT is the condition, when all feet
of the Pump or Motor are not in one plane.

26. ALIGNMENT :
How to DetectSOFT FOOT ?
Put Machine on base.
Do not tighten bolts.
Attempt to pass thin Feeler
Gauge Blade under a Foot.
If the blade passes, that foot has Soft Foot.
Check other feet.

27. ALIGNMENT :
How to RectifySOFT FOOT ?
Measure Soft foot gap.
Tighten all hold nuts
Put Dial Gauge on each foot & loosen the Bolt.
If foot rises, put Shims.
Repeat process for each foot.
Always tighten bolts in one sequence.

28. ALIGNMENT :
SOFT FOOT.
SOFT FOOT is the condition, when all
feet of the Pump or Motor are not in one
plane or Poor surface contact between
the underside of the Machine or Motor
and the base plate or frame.

29. ALIGNMENT TOLERANCES :
0.013 to 0.0254000 -6000
0.025 to 0.052000 –4000
0.05 to 0.101000 –2000
0.08 to 0.11<1000
TOLERANCE (mm)MACHINE RPM

30. METHODS OF ALIGNMENT :
Straight Edge, Feeler Gauge & Level.
Mathematical Method.
Reverse Indicator Method (graphic)
Face & Rim Alignment. (graphic)
Across Flex element. (graphic)
Laser Beam Method.

31. PRELIMINARY ALIGNMENT :
Straight Edge -

32. PRELIMINARY ALIGNMENT:
Feeler Gauge

33. ACCURATE ALIGNMENT :
Done with the help of
DIAL GAUGES.

34. DIAL GAUGE READING
1
0
0
20
-80
10
-90
-70
30
-60
40
-50
50
-30
70
80
-20
90
- 10
-40
60
1
2
3
45
TOP
Large Pointer = 0.00
Small Pointer = 3

35. DIAL GAUGE READING
1
0
0
20
-80
10
-90
-70
30
-60
40
-50
50
-30
70
80
-20
90
-10
-40
60
1
2
3
45
FAR
Large Pointer = 0.00
Small Pointer = 2-3
READING --0.60

36. DIAL GAUGE READING
1
0
0
20
-80
10
-90
-70
30
-60
40
-50
50
-30
70
80
-20
90
- 10
-40
60
1
2
3
45
BOTTOM
Large Pointer = 0.00
Small Pointer = 3 - 4
READING -+0.83

37. DIAL GAUGE READING
1
0
0
20
-80
10
-90
-70
30
-60
40
-50
50
-30
70
80
-20
90
- 10
-40
60
1
2
3
45
NEAR
Large Pointer = 0.00
Small Pointer = 2-1
READING --1.075

38. DIAL GAUGE READING
1
0
0
20
-80
10
-90
-70
30
-60
40
-50
50
-30
70
80
-20
90
- 10
-40
60
1
2
3
45
TOP
Large Pointer = 0.00
Small Pointer = 3

39. ACCURATE ALIGNMENT :
Dial Gauge -

40. 500 300
200
ACCURATE ALIGNMENT CALCULATION :
4.5
4.0
Coupling Gap Top= 4.5 mm. Coupling to Front Foot = 500 mm
Coupling Gap Bottom=4.0 mm. Front to Back Foot = 300 mm
Coupling Radius = 200/2= 100 mm. Total distance = 800 mm

41. Alignment calculations
Gap difference = 4.5 –4 = 0.5 / 2 = 0.25 (A)
a) Distance corrections = 800 / 100 = 8 (B)
So (A) x (B)=0.25 x 8 = 2 mm shim is to be
given under each back foot.
b) Corrections when front feet are to be raised :-
Distance corrections = 500 / 100 = 5 (B)
So (A) x(B) =0.25 x 5 = 1.25 mm shim is to be
given under each front foot.

42. REVERSE INDICATOR
ALIGNMENT METHOD.
Before starting the alignment, the MASTER must
be decided. The other machine must be moved to
align the shafts. First take the dial indicator
readings on the pump coupling and then the
readings on the motor coupling. On a sheet of
graph paper, layout the equipment being aligned.
The scale used is one small division equal to 1
inch.or to any suitable scale. Plot the distances.

44. TOP

45. FAR

46. BOTTOM

47. NEAR

48. Reading calculations :
Pump Motor
Horizontal.
Near + 0.006
Far (-) +0.004 (-)
+0.002 /2=
Horizontal.
Near -0.005
Far (-) -0.015 (+)
+0.010 /2=
Vertical.
+ 0.005
- 0.000
+ 0.005
Sag (-)-0.005 (+)
+ 0.010/2 =
Vertical.
-0.025
-0.000
-0.025
Sag (-)-0.005 (+)
-0.020 / 2 =-0.010 + 0.005
+ 0.005 + 0.001

49. Pump to motor alignment guide.
-Near side + Near side-on bottom + on bottom
+ Near side -Near side+ on bottom -on bottom
-Near side -Near side-on bottom -on bottom
+ Near side + Near side+ on bottom + on bottom
Reading on motorReading on pumpReading on motorReading on pump
Horizontal (Top view)Vertical (Side view)
Pump shaft Motor shaft

50. Reading calculations :
BottomTopBottomBottomPosition on
graph.
+ 0.001+ 0.005+ 0.005-0.010Reading
MotorPumpMotorPump
Horizontal.Vertical

51. P FFM
BF
P FFM
BF
HORIZONTAL SOLUTION
VERTICAL SOLUTION
0.010
0.019
0.007

52. Reading on pump.
0.00
+ 0.04
+ 0.03-0.02
Reading on motor.
0.00
+ 0.02
+ 0.04+ 0.06
Example –2 Reverse Indicator Method

53. Reading calculations :
Pump Motor
Horizontal.
Near + 0.06
Far (-) + 0.04 (-)
+0.02 /2=
Horizontal.
Near -0.02
Far (-) +0.03 (-)
- 0.05/2=
Vertical.
+ 0.02
- 0.00
+ 0.02
Sag NIL
+ 0.02/2 =
Vertical.
+0.04
-0.00
+ 0.04
Sag NIL
+0.04 / 2 = + 0.02 + 0.01
-0.025 + 0.01

54. Reading calculations :
BottomBottomBottomTopPosition on
graph.
+ 0.01-0.025+ 0.01+0.02Reading
MotorPumpMotorPump
Horizontal.Vertical

55. P M FF
BF
0.125
P
M FF
BF
0.01 0.0455
Vertical correction
Horizontal correction
0.05
(Scale 1=0.005)
Distance : P M=130 mm; M FF=180 mm; FF BF= 330 mm.
Scale 1= 100 mm
TOP
BOTTOM
FAR
NEAR

56. Conclusion :
Top –Bottom correction:
The motor shaft : 0.05 shim is to be given
under each front foot and 0.125 shim under
each back foot
Far –Near correction :
The motor shaft has to be shifted towards
near end. The front feet by 0.01 and the
back feet by 0.0455

57. MULTIUNIT ALIGNMENT
Plot all three units in a single piece of graph
paper using the reverse indicator method.
Unit 1 is master, there will be two lines for
unit 2 and unit 3. Draw an alternate
reference line close to the actual position of
the three units. Minimal movement is
required to get all units aligned.

59. Across the Flex Element

60. Positive reading means the
intermediate shaft axis is below
the gearbox.

61. Negative reading means the
intermediate shaft axis is above
Motor or the motor is below the
intermediate shaft.

63. LASER ALIGNMENT TOOL
S
M
S-unit on the master machine. M-unit on movable machine.

64. Rough Laser Alignment
1. Turn shafts with measuring units to position 9 o’clock. Aim the
laser beams to the centre of the closed target.
2. Turn shafts with measuring units to position 3 o’clock
3. Check where the laser hits.then adjust the beam half the travel in
direction to centre of the target.
4. Adjust the movable machine so that the laser beam hits
the centre.

66. Alignment and its effect on vibration.
Misalignment causes vibration.
There is no 1 to 1 relation with amount of
misalignment and amount of vibration.
Misalignment can cause failure of not only the
coupling but also Bearings and other moving
parts.
Highest reaction is on the free or outboard
bearing instead of inboard end.
Misalignment normally causes both Axial and
Radial vibration.

67. OTHER SOURCES OF HIGH AXIAL VIBRATION.
Bent shafts.
Shaft in resonant whirl.
Resonance of some components in axial direction.
Worn thrust bearing.
Worn helical and bevel gears.
A sleeve bearing motor hunting for its magnetic
centre.
Couple component of dynamic unbalance.
(So high axial vibration should not be concluded as the
problem of misalignment only)

68. CHARECTERISTICS OF MISALIGNMENT.
1. 2xRPM vibration.
2. Multiple harmonics.
3. Phase is the best indicator.
Phase difference across the coupling
approaches 180
O
(+ / -40
O
to 50
O
)

69. One Event
1 Revolution
Axial Direction
Rigid shaft.
Flexible shaft.
ANGULAR

70. ANGULAR MISALIGNMENT.
1. Primarily generates high axial vibration at
1X & 2X rpm..
2. Best detected by 180
O
phase change across
coupling in axial direction.
3. Amplitude of 2X or 3X RPM exceeds
approximately 30% to 50% of that at # X
RPM in the AXIAL direction

71. PARALLEL MISALIGNMENT.
1 st. Event
2 nd. Event
1 Revolution
Radial Direction
Rigid shaft.
Flexible shaft.

72. PARALLEL MISALIGNMENT.
1.More Radial vibration.
2. It causes phase difference to
approach 180
O
in Horizontal
direction.
3. 2X RPM exceeds 50% of 1X RPM.

73. MISALIGNED BEARING COCKED IN SHAFT..
1. A cocked bearing will normally generate
considerable axial vibration which affects 1X
RPM & 2X RPM.
2. If phase is measured in the axial direction at
each of a 4 points 90
O
apart from each other
a cocked bearing will be indicated by 180
O
phase shift from top to bottomjand side to
side.

74. COUPLING PROBLEMS
1.2X RPM will often respond to
coupling problems.
2.In these cases both Radial and Axial
direction will show a fairly
noticeable 3X RPM component.

75. Thank you !
Any questions please ?
Presented by :
A. Jayprakash