Flexible Coupling

Flexible Cou lin s All rights reserved to thepetrostreet.com

Prepa red by: Fraz

CONTENTS

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Purpose of Coupling Types of Couplings Rigid Couplings Func Functi tion ons s of of Fle Flex xible ible co cou u lin lin Types of Flexible Couplings Coupling selection chart

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The coupling must be capable of • • • •

Transmitting design torque. O eratin at maximum continuous s eed Handling speed and load transients Having minimum reactions on the drive


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TYPES OF COUPLINGS:

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Rigid Couplings Flexible Cou lin s

2.


Rigid Cylinder: 

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A key is always used that spans keyways machined in both shafts. Coupling halves are keyed onto the together.



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Following are the functions of a flexible

1. 2. . 4.

Transmit Power Accommodate misalignment Insure no loss of lubricants in grease packed couplings.


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Easy to install and disassemble

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torsional vibration Stay rigidly attached to the shaft. Withstand temperatures of environment or heat of friction


TYPES OF FLEXIBLE COUPLINGS

• 1. 2. 3.

TYPES OF FLEXIBLE COUPLINGS: Mechanical Element Elastomeric Element Metallic Membrane Disk T e


Chain Couplings: 

sprocket teeth connected by a double width chain 

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Max Speed : up to 5000rpm


Chain Couplings:

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Easy to disassemble and reassemble Fewer number of parts Speed limited due to difficulties in maintaining balancing requirements Limited allowable axial displacement


Gear Couplings: 

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with external gear teeth that are attached to the shaft A hub cover or sleeve with internal gear teeth engage with the shaft hubs to rovide the transmission of ower Lubrication of gear teeth is required.



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oup ngs:

Capacity : up to 70,000 hp ax pee : up o , rpm Backlash should be minimum and will be in accordance to the permissible misalignment oup ng assem y s ou ave m n mum 6mm of axial displacement Hardness of gear teeth<45Rc (Rockwell) oup ng gu guar s s ou eartg t


Gear Couplings:

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Torsional Tuning Shifting of one or more torsional natural system resonance at a known excitation Torsional tuning is accomplished by varying t e tors ona st ness o t e coup ng


Gear Couplings:

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Advantages: Allows freedom of axial movement

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Low overhung weight Good balance characteristics. ong s ory o su success u app ca ons Disadvantages: Requires lubrication. Separation of greases into soaps and oils. Centrifugal effect on oils / sludge formation. Tem Tem eratu erature re limit limitat atio ion n due to lubri lubrica cant nt


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Gear Co Gear Coup upli ling ngs: s: ere are on y two teet n contact when misalignment is present between each tooth set as shown in fig. In center of this icture the tooth is in pivoted position. At edges of this picture teeth are in ‘tilted’ position. mo e a misalignment. 2-D FEA model at 2” . All rights reserved to thepetrostreet.com

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Metal Ribbon Couplings: Consist of two hubs with axial ‘grooves’ on e ou er ame er o e u A continuous ‘S’ shaped grid meshes into the grooves. Misalignment and axial movement is achieved by flexing and sliding of the grid Lubrication of gear teeth is required.


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Metal Ribbon Cou lin s: Grid is fabricated from hardened, high strength steel. , Max Speed : to 6000rpm


Metal Ribbon Couplings: 

Advantages: Easy to assemble and disassemble.

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Tors Torsio iona nall lly y so soft ft.. Disadvantages: Requires lubrication. Temperature imite . Speed limited


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Flexible Link Coupling The flexible link coupling utilizes a series of cross laced, metallic links with one end of eac n a ac e o a sc moun e on the driver shaft, and the other end of each link attached to a disc mounted on the . The links are matched in pairs so that when one is in tension, the other is in com ression. Misalignment and axial displacement is accomplished by a flexing action in the series of cross links.


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Capacity : up to 30,000 hp Max Speed : up to 30,000rpm Shaft Bores : up to 7 in.

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astome merr c om ompres ess s on: An elastomeric medium used to transmit torque and accommodate misalignment. ‘ ’ torques. The spider is generally natural or synthetic rubber urethane n lon and teflon. Capacity : up to 67,000 hp / 100 rpm Max Speed : approx. 5000rpm



Elasto Ela stomer meric ic Com Compre pressi ssion: on: van ages: 

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Minimal wear in coupling. Act as vibration damper and isolator. .

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Tors Torsio iona nall lly y so soft ft.. Allows axial movement vibration. o u r ca ca on requ re re .

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dampens

axial

Disadvantages: 

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. Temp, oxidation of rubber and corrosive attack. Unde Undesi sira rabl ble e axia axiall fo forc rces es.. Heat generation due to cyclic flexing.


Ela last sto ome meri ric c Co Com m re ress ssio ion: n: 

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Failure modes: Abrasion: Rubber is a high friction ma er a , an m nor us s pro uce . Temperature deformation: Rubber aging (drying): organic materials, and there are some creatures that eat them


Elastomeric shear: 1. 2.

oo e s ear: s easy o n ns s a an maintain, and handle large misalignment. Tire type: Tire Tire beads beads are are clam clampe ped d to a hub hub on either side. Torque is transmitted by the tire in shear.

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bonded to a steel disk is pressed against another disk.



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Diaphragm Couplings: Transmission of power through two flexible . Bolted to the outer rim of the shaft hubs and connected via a spacer tube.

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absorbed by flexing of the diaphragm members.



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oup ngs:

Diaphragm has an effect of a spring

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rotating speeds or harmonics in the drive system.

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compressors. Capacity : up to 30,000 hp ,


Diaphragm Couplings: 

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Advantages: Exce Excell llen entt bala balanc nce e char charac acte teri rist stic ics. s. . Low coupling weight and bending forces. Accept epts high igh temp emperat rature enviro ironmen ment. Limited axial displacements and oscillation. Proper shaft spacing requirements. loads to shafting.


Flexible Disc Couplings 

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The flexible disk cou lin is ver similar to the diaphragm coupling Multiple, thinner discs are used as the flexing , diap diaphr hrag agm m elem elemen ents ts.. Two disc packs (or diaphragms) are needed o accommo a e para e m sa gnmen . A single disc can only handle pure angular misalignment.



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Flexible Disc Couplings Capacity : up to 65,000 hp / 100 rpm ,


100,000

Elastomer Inserts

Gear Quill shaft

HP/100RPM 10,000

Coil Springs

HIGH POWERS & SPEEDS

Multiple Disc

Taper Grid G rid FLEXIBLE in

1 000

Contoured Disc

Elastomer GENERAL

100

Chain

10

Pin & Bush

50 All rights reserved to thepetrostreet.com

100

1000

RPM

10000

50000

Coupling Balancing Requirements

AGMA Coupling Balance Class 4 6 7 8 9 10 11

Maximum Potential Displacement (rss Microinches) Over 32,000 , 16,000 8,000 4,000 2,000 1,000 500



‐ thePetroStreet team


Flexible Coupling

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