Nexus ESCO DISC Coupl Eng Data

8/13/2019 Nexus ESCO DISC Coupl Eng Data

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esco nexusComposite Disc Couplings

Application

Engineering Data

.


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esco nexusComposite Disc CouplingsAppl ication Engineering Data

. Sep2004esco couplings N.V. Culliganlaan 3 B 1831 Diegem Belgium tel + 32 2 7156560 www.esco-coupling.com

Introduction:esco nexus Composite Disc couplings were developed through research and testing with the goal of providingincreased endurance and fatigue life beyond the currently available composite couplings on the markettoday. The design stems from ACPTs composite experiences with military vehicles such as tanks,amphibious assault vehicles and trucks, rotary winged aircraft, performance racing and various industrialapplications.

Product Description:esco nexus composite couplings are non-lubricated, disc type couplings made from advanced compositematerials. The floating spacer shaft and flanges are made from composite materials that ensure strengthand endurance while delivering light weight, corrosion resistance and ultra-violet light protection. Thedisc type flexible elements are made from a combination of stainless steel bushings, advanced compositedisc-links and a urethane encapsulation to provide a unitized assembly with a theoretical infinite fatigue

life. The flexible elements are rated for 1misalignment and carry a 4 times peak overload rating whenapplied at 2.0 service factor. The hubs and hardware are made from stainless steel for added corrosionprotection in aggressive environments. The combination of high peak overload capacity and high-strength composites makes this product a heavy-weight title contender despite its light weight.

Bolt, Hex, Washer Head

Stainless Steel

Spacer Bushing

Stainless Steel

Nut, Hex w/ Nylon Lock Ring

Stainless Steel

Floating Spacer Shaft

Composite

Flexible Element,

Nexus Disc,

Unitized

Composite

Hub

Stainless Steel

Set Screw

Stainless Steel

The floating spacer shafts are made from Graphite and/or E-glass fibers embedded in an epoxy matrix.The epoxy resin is filled with a UV protective additive and cured at high temperature. This systemprovides corrosion resistance that exceeds stainless steel.

There are five sizes of flexible elements that range from 75 kW to 675 kW to serve most electric motordriven applications. These flexible elements are combined with matching hubs, hardware kits and floatingspacer shafts to provide the most economical selection for a given application

Nomenclature:Coupling size, i.e. A300, refers to the A series disc couplings followed by the flexible element kilowattrating at 1.0 service factor. In this example the A300 is rated for 300 kW or about 225 horsepower @1800 RPM.

SES stands for Shaft End Separation and is the distance between the faces of the connected equipmentshafts. In the case of a cooling tower this length is between the face of the gear box shaft (driven) andthe face of the electric motor shaft (driver). SES is sometimes referred to as DBSE (Distance BetweenShaft Ends).


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esco nexus Composite Disc CouplingsAppl ication Engineering Data

Sep2004esco couplings N.V. Culliganlaan 3 B 1831 Diegem Belgium tel + 32 2 7156560 www.esco-coupling.com

1) Maximum SES is based on a 1.30 minimum critical speed safety factor per Cooling Technology Institute, Chapter 10specifications.

L = SES

D

C A

B

Spacer Tube O.D.

Table 1 - General Dimensions (inches)

1 2 3 4 5 6 7 8 9 10

Coupling Size Max. Bore A B C DSpacerShaft

SpacerTubeO.D.

Min. SES"L"

(inches)

1Maximum SES

@ 1800/1500 RPM(inches)

S3 82 / 92A75 2.13 5.25 2.25 2.93 0.50

M39

100 / 110

S3 82 / 92

M3 100 / 110A150 2.88 5.25 2.25 2.93 0.50

L3

3.3

9

114 / 125

M4 120 / 132

L44.3

137 / 150

L5 5.3 153 / 168A225 4.00 7.03 3.13 3.88 0.63

L6 6.3

12

168 / 184

M4 120 / 132

L44.3

137 / 150

L5 5.3 153 / 168A300 4.00 7.03 3.13 4.38 0.75

L6 6.3

12

168 / 184

L6 6.3 168 / 184

L7 7.3 181 / 198

L8 193 / 211

X8 212 / 232

A675 4.19 9.50 3.75 5.50 0.75

XH8

8.3

14

226 / 248

Table 2- Engineering Data1 2 3 4 5 6 7 8 9

CouplingSize

Max.Continuous

Torque (lb-in .)@ 1.0 sf

PeakOverload

Torque (lb-in.)

Axial Capac ityPer End(inches)

SpacerShaft

Weight @Min. SES

(lbs)

WeightChange PerInch (lbs)

Wr2@

Min.SES

(lb-in2)

Wr2

ChangePerInch

(lb-in2)

S3 13.1 0.105 35 0.218A75 3,600 7,200 0.03

M3 13.0 0.089 35 0.185

S3 11.6 0.105 33 0.218

M3 11.5 0.089 33 0.185A150 7,200 14,400 0.03

L3 11.3 0.063 32 0.131

M4 31.4 0.154 134 0.666

L4 31.0 0.110 132 0.472

L5 35.7 0.136 162 0.902A225 10,800 21,600 0.04

L6 41.4 0.162 214 1.536

M4 36.2 0.154 134 0.666

L4 35.8 0.110 132 0.472L5 40.5 0.136 162 0.902

A300 14,400 28,800 0.04

L6 46.2 0.162 214 1.536

L6 69.5 0.162 630 1.536

L7 77.8 0.189 735 2.413

L8 87.4 0.215 896 3.573

X8 87.4 0.215 896 3.573

A675 32,500 65,000 0.05

XH8 87.4 0.215 896 3.573


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Coupling Selection:

Step1: Coupling selection is determined by comparing the full load motor (driver) torque timesrequired safety factor to the coupling Continuous Torque rating at 1.0 service factor. Electricmotor full load torque (lb-in) is established by multiplying the nameplate horsepower rating(Hp) by 63,025 and then dividing by nameplate full load RPM (usually between 1750 and1790 for 4 pole electric motors). Formula is as follows:

63025

RPMTHp = orRPM

HpT 63025=

Example: Motor nameplate Hp = 100Motor nameplate full load RPM = 1775Service Factor = 2.0 (for cooling towers)

inlbT =

= 71001775

263025100

Compare 7100 to the maximum continuous torque ratings in Table 2 - Engineering Data,Column 2 until you find the first size that equals or exceeds this value. In this case theselection is A150.

Step 2: Shaft End Separation (SES) is the distance in inches from the face of the gear box shaft tothe face of the electric motor shaft (tolerance = 0.06). In this example we will use 95.00.

In Table 1 - General Dimensions find the row for A150 and read across to the right in Column7 and notice the possible selections (in this case S3, M3 or L3). In Column 10 you will findthe values for the maximum SES permitted for each type spacer shaft. Select the first onethat exceeds the actual SES required for the application. In this case it is M3. The completemodel description is the combination of the coupling size (A150) and the spacer shaft (M3)designated as A150-M3.

Total Weight of Assembly:

Step 1: To establish the total weight of a complete coupling assembly locate the coupling size inTable 2, Column 1; locate spacer shaft in column 5; note the weight at minimum SES in

Column 6 and the weight change per inch in Column 7. For this example, A150-M3, thevalues are 11.5 and 0.089 respectively.

Step 2: In Table 1, Column 9, note the minimum SES in inches (9). Subtract this value from theactual SES (95 9 = 86). Multiply the weight change per inch times this adjusted value (86 x0.089 = 7.654 lbs) and then add the weight at minimum SES to arrive at the total weight (7.7+ 11.5 = 19.2 lbs).

Total Wr2of Assembly:

Step 1: Similar to above except substitute the Wr2in Column 8 and 9 in Table 2 for the same coupling

and complete Step 2 above with these substituted values. For this example, A150-M3, thevalues are 33 and 0.185 respectively.

Step 2: In Table 1, Column 9, note the minimum SES in inches (9). Subtract this value from theactual SES (95 9 = 86). Multiply the Wr

2change per inch times this adjusted value (86 x

0.185 = 12.9 lb-in2) and then add the Wr

2at minimum SES to arrive at the total Wr

2(33 +

12.9 = 44.9 lb-in2).

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Assembly and Operat ion

Shown below is the complete assembly that includes 2 hubs with set screws, 2 flexible elements, 2hardware sets and 1 floating spacer shaft. The hardware set includes enough bolts, nuts and bushings toassemble one flexible element to the hub and spacer shaft. The bolts are flanged, hex head to eliminatethe need for separate washers that are quite often dropped and lost during the installation process. Thebushings are installed in the large clearance holes in the hub and spacer shaft flanges. These bushingslocate the self-locking nuts outside the flange faces so that a wrench or socket can be easily used to

torque the nuts.

Why is it called a floating spacer shaft? In a disc coupling assembly, the spacer shaft is only affixed toevery other hole in the flexible elements. The alternate holes are affixed to the hub flange. In this way,flexible elements act like springs to allow the spacer shaft to move axially to accommodate thermalexpansion or axial movement of the connected equipment. The spacer shaft is allowed to float in order toseek a neutral position between the flexible elements and equalize the stresses encountered.

Why are there two flexible elements? A single disc type flexible element can accommodate some axialmovement and either parallel or angular misalignment, but not both simultaneously. However, two disctype flexible elements separated by a floating shaft can accommodate parallel offset, angularmisalignment and axial movement simultaneously while balancing the stresses between themselves.This type of coupling system has relatively low reaction forces that reduce the loads on the connectedequipments shaft bearings.

Hub Flange

Floating Spacer ShaftFlexible Element

Flanged Hex Head Bolt

Bushing

Self-locking Nut

Spacer Flange

Hub

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Critical Speed

Floating Spacer Shaft

1000

1500

2000

2500

3000

3500

4000

4500

5000

80 100 120 140 160 180 200 220 240 260 280

Length (inches)

CriticalSpeed(RPM

)

XH8

L4

L5

L6

L7

L8

X8

The critical speed of the floating spacer shaft can be determined from the chart above. Once you knowthe spacer shaft designation (i.e. L4) and the SES you can plot the point on the chart to determine thecritical speed. For example, if the SES is 125 and the spacer shaft is L4 find the intersection of x axis at125 with the curve marked L4 and read the critical speed on the y axis. In this example the value is2825 cycles per minute.

Critical Speed SafetyFactor for 1800 RPM

Critical Speed SafetyFactor for 1500 RPM

M4

L3

M3

S3

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Company: Date:

Name: ACPT Quote No.

Tel, Fax: Prepared By:

Email:

Appl ication Data (completed by customer)

Motor FrameMotor RPM

Motor Nameplate Hp Rating

Motor Shaft Diameter

Motor Shaft Keyway

Gear Box Model

Gear Box Ratio

Gear Input Shaft Diameter

Input Shaft Keyway

Fan BHP Load

Fan RPM

No. of Fan BladesBlade Pass Frequency (CPM)

Application Type

Required Service Factor

Coupling Data (completed by ACPT)Product ID Code

Continuous Torque Rating

Peak Torque Rating

Service Factor (based on motor rating)

Lateral Critical Speed Nc

Nc Safety Factor 1.30

Floating Shaft OD

Misalignment Tolerance 1 /flexible element

Dynamic Balance Class Q6.3

Hub and Hardware Material Stainless Steel

Flexible Disc Material Composite

Maximum Coupling Diameter

Shaft End Separation (SES)

Gear Reducer Motor

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Nexus ESCO DISC Coupl Eng Data

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