This webinar will place the spotlight on gear couplings with a focus on factors to consider when making a coupling selection for your application. Topics covered will include basic sizing, application criteria, coupling design features and the variety of coupling types available.

1. Selecting the Right Gear
Coupling for Your
Application

2. q This webinar will be available afterwards at
www.designworldonline.com & email
q Q&A at the end of the presentation
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Before We Start

3. Moderator Presenter
Miles Budimir
Design World
Paul Konkol
Altra Ameridrives Gear Couplings

4. Design World Webinar
Selecting the right gear
coupling for your application
April 29, 2015

5. What is a Coupling ?
A Flexible Coupling is a machine part that transmits
rotating power from one shaft to another while
accommodating misalignment and axial displacement
between the two shafts.

6. The basic functions of a flexible coupling:
• Transmit power
• Accommodate misalignment
• Compensate for shaft end movement
Basic Coupling Functions

7. Transmit Torque
While allowing for:
Misalignment
Axial Movement
DRIVERDRIVEN

8. • Torque: The tendency of a force to cause or change
rotational motion of a body, calculated by multiplying Force and
distance. Defined more fully in the Torque section below.
• Misalignment: The state of being not in alignment.
Alignment is generally defined as the state where opposing
equipment shaft centerlines are coaxial. For machinery and
couplings, it is the proper orientation of mechanical parts to
obtain minimal wear and/or dynamic forces.
• Hub: The coupling component which is machined for
mounting on a shaft.
• Spacer: A removable center member that provides a
specified axial shaft separation.
• Distance Between Shaft Ends (DBSE): The
distance from the face of one shaft to the face of the next shaft.
• Shaft: The revolving cylindrical bar, the centerline of which is
also the center of rotation for the components to which it is
attached, through which torsional power is transmitted or
delivered.
• Bore: Cylindrical or conical holes in hubs of couplings with
axes coincident with the rotational axis of the coupling.
• Flexible Element: The part of a coupling which
provides flexibility. There are 3 main categories:
Mechanical, Metallic, and Elastomeric.
• Sleeve: A gear coupling component with internal teeth.
• Hardware: The nuts, bolts, washers, etc., which are
used to attach the various coupling components together.
• Clearance Fit: A condition where the hub bore
diameter is equal to or larger than the shaft diameter.
• Interference Fit: A condition where the hub bore
diameter is equal to or smaller than the shaft diameter.
• Pilots: A surface that positions a coupling component,
subassembly or assembly.
• Key: A mating torsional load transmitting member placed
in a groove in both shaft and hub.
• Keyway: The axial groove in the hub that holds the key
in the proper location.
Coupling Terminology

9. Basic Torque Calculation
Torque = Power x Unit Constant
Speed
• in-lb. = HP x 63025 / RPM
• Nm = kW x 9554 / RPM
• HP/100 RPM = HP x 100 / RPM

10. Torque
=
HP transmitted x 63,025 x Service Factor
RPM

11. Service Factors are a multiplier to the calculated torque when selecting a
coupling.
• Selection Torque = Calculated TQ x SF
• Note: Different coupling types and/or manufacturers recommend different service
factors for similar operating conditions. Always check your catalog
CLASS SMOOTH STEADY MODERATE MEDIUM HEAVY EXTRA HEAVY EXTREMELY HEAVY
DRIVER
TYPE
MOTOR OR
TURBINE
MOTOR OR
TURBINE
MOTOR OR
TURBINE
MOTOR OR
TURBINE
HIGH STARTING
TORQUE MOTOR
OR ENGINE ENGINE ENGINE
LOAD
TYPE
- SOFT START WITH STEADY
LOAD
- CENTRIFUGAL
EQUIPMENT
- NORMAL STARTING LOADS
- SLIGHT TORQUE
VARIATIONS
- ABOVE AVERAGE
STARTING LOADS
- MODERATE LOAD
VARIATIONS
- HIGH STARTING TORQUE
- MEDIUM TO HEAVY LOAD
VARIATIONS
- MILD SHOCK LOADING
ENGINES WITH SMOOTH
LOADING
- EXTREME RELIABILITY
- HEAVY SHOCK LOADING
- LIGHT TO MODERATE
REVERSING
- EXTREME SHOCK
LOADING
- HEAVY REVERSING WIDE
TORQUE VARIATION
SERVICE
FACTOR 1.0 1.5 2.0 2.5 3.0 3.25 4.0
Service Factors

12. Angular
Misalignment
Parallel Offset
Misalignment
Types of Misalignment

13. Misalignment
Parallel offset
Combination of both
Angular misalignment

14. Types of Misalignment
• Axial Misalignment or End Float
o Some couplings will limit shaft movement, others will not
o Sometimes limited end float (LEF) devices may be added
to a coupling

15. A. Small amount
• Thermal growth
• Bearing float
B. Large amount
• Axial adjustment
• Operational shifting
Axial Movement

16. Coupling Categories and Types
Gear Chain Grid UJoint
Mechanical
Disc Diaphragm
Metallic
Shear Compression
Elastomeric
Pin & Bushing Spring Slider Block
Miscellaneous

17. Mechanical
UJoint
Gear
Chain
Grid

18. Elastomeric
Shear
Compression

19. Metallic
Disc
Diaphragm

20. Performance
L-jaw
Sure-Flex®
Dura-Flex®
Gear
Form-Flex®
Grid
Make to Stock
Modify/MTO
Price
Couplings Cover a Wide Range

21. So, which is the right coupling for my application?

27. Types of Couplings & Application Requirements
Coupling
Characteristics
Gear Spindle Grid U Joint Elastomeric
Shear
Elastomeric
Compression
Disc Diaphragm
Lubrication Yes Yes Yes Yes No No No No
Backlash Med High Med None None Low None None
Overhung
Moment
Med High Med High High High Low Low
Unbalance Med High High High High High Med Low
Bending
Moment
High High Med High Low Med Med Med
Axial Force High High Med High Low Med Med Med
Torsional
Stiffness
High High Med High Low Med High High
Damping Low Low Med Low High Med Low Low
Coupling selection based on application needs

28. Costs and BenefitsCriteria
Coupling Types
Elastomeric -­‐‑ Shear
Elastomeric -­‐‑ Compress
Tire
Block
Sleeve
Jaw
Curved-­‐‑Jaw
Block
Gear
Disc
Grid
Lubrication
N
N
N
N
N
N
Y
N
Y
Ease of Installation
++
+++
+++
+++
+++
+++
+
+
+
Fail Safe
N
N
N
Y
Y
Y
N
N
N
Misalignment Rating
+++
+
++
+
+
+
++
+
+
Purchase Cost
$$
$
$
$
$
$
$$$
$$$
$$
Maintenance Cost
N
N
N
N
N
N
Y
N
Y
Replacement Cost
$$
$
$
$
$
$
$$$
$$$
$$
Installation Cost/Time
++
+++
+++
+++
+++
++
+
+
+
Life
++
+
++
+
+
+
+++
+++
++
Torsional Stiffness
Low
High
Low
High
High
High
Highest
Highest
Low
+++ = BEST
++ = BETTER
+ = GOOD
$$$ = HIGHEST
$$ = LOWER
$ = LOWEST

29. Why Select a Gear Coupling?
Coupling
Characteristics
Gear Spindle Grid U Joint Elastomeric
Shear
Elastomeric
Compression
Disc Diaphragm
Lubrication Yes Yes Yes Yes No No No No
Backlash Med High Med None None Low None None
Overhung
Moment
Med High Med High High High Low Low
Unbalance Med High High High High High Med Low
Bending
Moment
High High Med High Low Med Med Med
Axial Force High High Med High Low Med Med Med
Torsional
Stiffness
High High Med High Low Med High High
Damping Low Low Med Low High Med Low Low
Gear Coupling is selected because it is torque dense, has axial capacity
independent of angular misalignment, large bore capacity, and long life.

30. Why a Gear Coupling?
• High torque
• High misalignment
• Axial capacity

31. Basic Gear Coupling Parts
Lube Plugs
Flange Nuts & Bolts Sleeve
O-ring Seal
Hub

32. How a Gear Coupling Transmits Torque
Torque is transmitted on
the flank or face of the
gear tooth
Major Diameter Sleeve
Piloting

33. • Gear teeth are either
straight or crowned
• Clearance in gear mesh
allows for misalignment
• Crowned tooth allows for
greater misalignment,
higher torque capacity,
less backlash
Gear Tooth Design

34. Crowned or Fully Crowned Gearing
A) Flank (Face)
B) Tip (and Root)
C) Chamfer

35. When everything is
“perfectly” aligned
all teeth share the
load equally
How a Gear Coupling Works

36. As you misalign, fewer and fewer
teeth are in contact
Ratings are based on the torque
that can be transmitted at a given
misalignment
Reduce your misalignment,
increase your ratings
How a Gear Coupling Works

37. Fully Crowned Gearing Allows for
Max Misalignment

38. Fully Crowned Gear Reduces
Backlash and Vibration

39. Gear Couplings Require Lubrication
Original gear couplings 75+
years ago were filled with oil for
lubrication
A metal labyrinth seal and
centrifugal force kept the gear
mesh lubricated

40. O-ring Seal
Buna-N O-ring seals keep
contamination out, and lubricant in.
Designed to accommodate
temperatures up to 250°F.
Viton seals are available for
temperatures up to 550°F. O-ring Seal
Clean grease of the proper amount and type will give
longest life

41. Recommended Grease
Suggested grease by manufacturer and operating conditions

42. Gear Coupling Standards
• Flange Diameter is standard for manufactures
• Shrouded or Exposed bolt pattern is standard
• Allows for Identification & Half-to-Half Interchangeability

43. Standard AGMA Nomenclature Size 1 ½ to 7
Size
Mfg. K
Mfg. F
Mfg. A
O.D.
# SB Bolts
# EB Bolts
1-­‐‑1/2
1-­‐‑1/2H
1015
201.5
6.00”
8
8
2
2H
1020
202
7.00”
10
6
2-­‐‑1/2
2-­‐‑1/2H
1025
202.5
8.38”
10
6
3
3H
1030
203
9.44”
12
8
7
7H
1070
207
20.75”
n/a
16
O.D.
• Measure flange O.D.
• Count the bolts
• Step in ½ sizes

44. Special Coupling Functions
Many couplings today are special made to order
and incorporate other special features.
§ Allow for axial travel
§ Maintain sleeve bearing motor
rotor position (Limited End Float or
LEF)
§ Allow for extended DBSE
§ Protect Equipment from overload
§ Dampen vibration and reduce
peak or shock loads
§ Electrically insulate the driver
from the driven equipment
§ Incorporate a brake disc or drum
§ Tune a system out of a torsional
critical
§ Support the rotor of a generator or
other radial load (single flex)
§ Electrically insulate the driver
from the driven equipment
§ Measure output torque of driven
equipment
§ Support axial loads on vertical
installation
§ Support other PT Components
§ V-Belt Drive, Fluid Drive, Clutch, etc.

45. Special Coupling Functions
Application Data Form to gather all information
important to the installation
§ HP, speed, DBSE, shaft sizes,
SF, temperature, etc.
§ What is currently being used?
§ Drawings of existing
application
§ What changes have been
made since original
installation?
§ What operational problems
are there?
§ Special documentation

46. BORES, FITS AND HUB MOUNTING

47. Hub to Shaft Fits
• Slip or Clearance Fits
o Hub bore is always larger than shaft OD
• Press or Interference Fits
o Hub bore is always smaller than shaft OD

48. Clearance Fits
• Use for Low Speeds
o 1800 to 3600 RPM max
• Requires set screws and keyway
o Worse for balance
• Low HP ranges
o Generally 250 HP and under
• Smaller Shaft Diameters
o Generally 3 3/8” or less
• Risk of Fretting

49. Interference Fits
• Light: under .0005 in/in
o Must use a key – minimal interference will slip under heavy load
o AGMA Standard A86
o Hub mounting: Heating necessary
o Stresses are usually not an issue
• Medium: ~.0005 - .0015 in/in
o Usually tapered shaft and some keyless fits
o AGMA standards A86 & A91
o Hub mounting: Must be heated or hydraulically mounted
o Stresses may need to be checked
• Heavy: ~over .0015 in/in
o Keyless fits
o AGMA Standard A91
o Hub mounting: Heating necessary
o Stresses need to be checked

50. AGMA Fit Tables

51. Interference Fit Calculations
• Steel expands .0006”/inch of diameter per 100°F temp rise
• Heat the hub to expand bore by 150%+ of the interference
• Example: 5” dia. shaft with .004” interference
• 5” dia. x .0006” = .003” expansion per 100°F temp rise
• .004” x 150% = minimum .006” growth
• .003”/100°F x 2 = .006” bore growth = min 200°F temp rise
• At 70°F temp, need to heat hub to at least 270°F
Ø 350°F is recommended, even heat distribution, less that 600°F

52. Interference Fit Hub Installation
• Calculate the correct temperature rise
• Make sure bore and shaft are clean and free
of burrs
• Plan how you will handle the heated hub
• Heat hub thoroughly – if not heated through,
hub may cool, shrink and bind before
completely on the shaft
• Shield shaft and seals from over-heating
when you install the hub
• Quickly and safely position the hub on the
shaft and allow it to cool

53. Metric vs. English Shaft Specification
Inch Shafts
• Standard AGMA tolerances
• Square keys
• Half in hub / half in shaft
Metric Shafts
• Various Metric standards DIN Standards
• Rectangular keys
• Keyway depth per metric standards
• Overkey dimension for keyway depth
Inch Keyways
Metric Keyways

54. Fitting of Keys
1. Tight Fit in Shaft Keyway
2. Sliding Fit in Hub Keyway
3. Clearance over Top of Key
4. Chamfered Key Corners

55. Interference Fit with Key

56. The proper gear coupling
selection and design will give
you the maximum
misalignment capacity &
maximum torque capacity for
the longest life in your
application.

57. Questions?
Miles Budimir
Design World
mbudimir@wtwhmedia.com
Twitter: @DW_Motion
Paul Konkol
Altra Ameridrives Gear Couplings
Paul.konkol@ameridrives.com

58. Thank You
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