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Gear CouplingPMANF-2014

Contents

What is Coupling ?1

Types of Coupling2

Gear Coupling 3

Basic Principle4

Machine gear shaping, Assembly , 3D drawing5

load calculations 6

Contents (continue)

Catalogs9

Misalignment 8

Crowned Gear Tooth7

Types of gear coupling8

Advantages and disadvantages9

What is Coupling ?

A coupling is a device used to connect two

shafts together at their ends for the purpose

of transmitting power.

The primary purpose of couplings is to join

two pieces of rotating equipment while

permitting some degree of misalignment or

end movement or both.

Diagram

rigid couplings

are the most

effective choice

for precise

alignment and

secure hold.

Flexible couplings

are used to transmit

torque from one shaft

to another when the

two shafts are slightly

misaligned. Flexible

couplings can

accommodate varying

degrees of

misalignment up to 3°

Coupling

Requirements of good shaft alignment/ good coupling setup

it should be easy to connect or disconnect the coupling.

it does allow some misalignment between the two

adjacent shaft rotation axes.

it is the goal to minimize the remaining misalignment in

running operation to maximize power transmission and to

maximize machine runtime (coupling and bearing and

sealing lifetime).

it should have no projecting parts.

it is recommended to use manufacturer's alignment target

values to set up the machine train to a defined non-zero

alignment, due to the fact that later when the machine is

at operation temperature the alignment condition is

perfect

Gear Coupling

A gear coupling is a mechanical device for transmitting

torque between two shafts that are not collinear.

Each joint consists of a 1:1 gear ratio internal/external

gear pair. The tooth flanks and outer diameter of the

external gear are crowned to allow for angular

displacement between the two gears. Mechanically, the

gears are equivalent to rotating splines with modified

profiles.

Gear couplings are generally limited to angular

misalignments, i.e., the angle of the spindle relative

to the axes of the connected shafts, of 4-5°

Basic Principle

The function of the gear coupling is to connect two

shafts. The gear coupling consists of two inside

metal gear halves each connecting to one shaft and

to the external gear, and a metal external gear

connecting the inside gears.

Gear Couplings are best suited for heavy load, slow

speed applications.

Diagram

shaft

key

External

teethed

forged

hubs Internal

teethed

Forged

sleeves

bolts

Uses

Shaft couplings are used in machinery for several

purposes, the most common of which are the following:

To provide for the connection of shafts of units that

are manufactured separately such as a motor and

generator and to provide for disconnection for

repairs or alterations.

To provide for misalignment of the shafts or to

introduce mechanical flexibility.

To reduce the transmission of shock loads from

one shaft to another.

To introduce protection against overloads.

To alter the vibration characteristics of rotating units.

Approved materials

Shafts, pinions, wheels and wheel rims of

gears in the main propulsion plant are

preferably to be made of forged steel. Rolled

steel bar may also be used for plain,

flangeless shafts. Gear wheel bodies may

be made of grey cast iron , nodular cast iron

or may be fabricated from welded steel

plates with steel or cast steel hubs.

Machine gear shaping a gear coupling sleeve

Assembly

3D drawing

load calculations

Click Here

Fully Crowned Gear Tooth

Fully-Crowned Tooth represents the ultimate

achievement in the art of gear tooth design, wherein all

three working portions of the tooth are crowned. As a

result, the teeth act much like a rocking chair, capable

of sliding freely in the axial direction without digging or

gouging the internal mating teeth.

Crowned Flanks : Flanks of

the teeth are crowned so that

tooth thickness is greatest at

that center of the tooth. This

assures larger contact area per

tooth for higher torque

requirements and puts more

teeth in contact for a given

angle. Actual tooth loading

takes place near the center of

the tooth face where tooth

thickness is greatest, Crowned

flanks also eliminate end-of-

tooth loading, provide optimum

load distribution, and

accommodate all types of

misalignment with minimum

backlash.

Crowned Tips : Tips of

teeth are crowned. The

crowned tip contacts the

root of internal gear teeth

in the external sleeve,

accurately piloting the

sleeve with true concentric

ball-and-socket action. This

allows minimum diametric

sleeve clearance and

centers the sleeve

physically to assure good

dynamic balance

characteristics under

various loading and

misalignment conditions.

Crowned Chamfers :

Faces of the teeth

adjacent to the tips

are chamfered to

eliminate interference

with the sleeve tooth

fillets. This allows the

true involute flanks of

the gear teeth to be in

contact with the

sleeve teeth and

assures freedom to

misalign.

Tooth forms in the Coupling

Three types of external teeth are used in gear couplings.

Straight Teeth: The external teeth in the hub are straight.

During the condition of misalignment in the coupling the

contact pattern between the internal gear and the external

gear tends to be line type of contact as shown in the figure.

Crowning with constant radius: The external teeth are

barrel shaped with a constant radius in order to increase

the area of contact and move the area of contact to a near

middle portion of the teeth.

Crowning with variable radius: The external teeth are barrel

shaped with a variable radius instead of constant radius.

This increases the area of the contact significantly

compared to that of the constant radius crowning.

Types of gear coupling

FULL GEAR COUPLINGS HALF GEAR COUPLINGS MOTOR TYPE

GEAR COUPLINGS

Types of gear coupling

FLOATING SHAFT TYPE

GEAR COUPLINGSSPACER TYPE

GEAR COUPLINGS

Selection procedure for gear couplingDetermine transmitted Torque or Effective kW/rpm

𝐓𝐨𝐫𝐪𝐮𝐞 𝐞𝐟𝐟𝐞𝐜𝐭𝐢𝐯𝐞 =𝟗𝟓𝟓𝟎 𝐗 𝐤𝐖 𝐓𝐫𝐚𝐧𝐬𝐦𝐢𝐭𝐭𝐞𝐝 𝐗 𝐒𝐞𝐫𝐯𝐢𝐜𝐞 𝐅𝐚𝐜𝐭𝐨𝐫

𝐫𝐩𝐦

2) Shaft Diameter

Next check whether the shaft diameters of the driving and driven

equipment lie within the listed maximum bore. If not, go for a

bigger size of coupling which will be accommodating the shaft

diameter.

3) Maximum Speed of Application

Check whether the required speed of the shaft/coupling is within

the speed values applicable for the selected coupling size. These

speeds are given only as a guide since the maximum speed

depends on the system characteristics.

4) Space Limitations

To check space limitations dimensions of the selected coupling

should be compared with space provided in the application to

assure proper clearances. Shaft extensions, separation and

clearances to align coupling should be checked.

Misalignment

Spacer Gear Couplings

This type are designed to accommodate angular & parallel

misalignment or a combination of both. Besides this, it can

also accommodate axial misalignment (end float).

Custom built Gear Spacer Couplings and Torsion Shaft Gear Couplings are

also manufactured & supplied as per requirements

Catalogs

Click

Here

Advantages

Text

Advantages

Text

•Allows

freedom of

axial

movement

•High

transmission

efficiency

* Capable of

operating at

high speeds

* Full Teeth

engagement

– Reduces

uneven wear

Text

Text

Low overhung weight,

Compact.

* Good balance characteristics

* Generally used up to 120°C.

Disadvantages

1

Requires

lubrication.

Temperatur

e limitation

due to

lubricant

2

Separation

of greases

into soaps

and oils

3

Centrifugal

effect on oils

/ sludge

formation

Continuous and flanged sleeve gear

couplings are known for serve

applications involving extended

distances between shaft ends, mill

motors, and limited end float

situations.

Application

Steel Mill

installed on chain conveyor system

widely used in steel mill ,thousands

of couplings construct production

line of steel mill.

Conveyor System

wildly used on crane or

conveyor system.

Gear coupling with disc as

main transmitting shaft.

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