V-Belt Drive Application

Rick Stewart

Belt Drives on HVAC Equipment:Advantages, Terms, Belt Construction, Belt Length Variation, Replacement & Equipment Dynamics,

Proper Drive Maintenance:Importance, Safety, Belt Tension, Worn Sheave, Increasing Drive Life

Energy Savings Opportunities:Upgrade Belt, Sheave Wear & Proper Tension

Energy Savings Opportunities Part II:Retrofitting old worn out drives

Sustaining Drive Efficiency:Self- Tensioning Motor Bases & Automatic Bearing Lubricators

Summary:Tools & Available ResourcesQuestions? & Contact Information

WHAT WE WILL COVER:

Belt Drives on HVAC Equipment

Equipment Dynamics

Traditional CenterDistance Requirement(20-28 inches)

New Center DistanceTrend (12-18 inches)

• Shorter Center Distances – Increased Belt Cycles• Lighter Structural Framework – Harder to maintain

proper alignment & drive tension. Drive is twisted causing issues.• Higher Speeds – Need for better system balance to prevent

vibration & noise issues.

OEM trends for smaller center distances. This puts much greater but demands more for the entire drive

• Economical -Low initial cost and low cost to maintain• Quiet - Smooth, quiet operation• Clean- No lubrication is required• Easy to install & maintain – Belts wear gradually • Forgiving - Withstand installation/maintenance abuse & still give

good drive life• Efficient – Drive performance between 94 - 98% when

maintained & installed correctly• Availability – Replacements can be purchased everywhere• Versatile – cover a wide range of horsepower's & speeds• Rugged – Last for long periods of time Shock Absorbing

Advantages of using V-Belt drives

Key Terms and Definitions

• Center Distance - Amount of distance between driver and driven shafts

• Service Factor - Required Horsepower x Service Factor

= Design Horsepower

• Datum Diameter – The Datum Diameter as the effective diameter for determine the pitch length of the belt for center distance calculation. Listed for A, B, C & D Sheaves. Adopted in 1987 by RMA/MPTA.

• Pitch Diameter – The diameter where the belt cords are placed in a belt.

• Torque - A twisting or turning force As speed decreases, torque increases

• Ratio – Driver divided by Driven

Fabric Polyester cords Neoprene Rubber

Belt construction What they do:

Transmit torque & HorsepowerHeat and Oil ResistantStatic ConductingLow VibrationLow MaintenanceGood for Shock Loads

Wrapped Belt

Cogged (Raw-Edge) Belt

Fabric Polyester cords EPDM

Cogged Belts: Transmit more horsepower Run cooler; Ave 16º to 30ºTemperature Range -60º to +250ºSlightly louderNeed closer alignment

Belt Length Variation

Standard Standard Datum Lengths Permissible Matching Matching Matching

Length Cross Section Deviation from Limits for Limits for Limits for

Designation A,AX B,BX C,CX D Std. Datum Lgth One Set Code 1 Machine

26 27.3 +0.6 -0.6 0.15 0.15 0.10

31 32.3 +0.6 -0.6 0.15 0.15 0.10

35 36.3 38.8 +0.6 -0.6 0.15 0.15 0.10

38 39.3 39.8 +0.7 -0.7 0.15 0.15 0.10

42 43.3 43.8 +0.7 -0.7 0.15 0.15 0.10

46 47.3 47.8 +0.7 -0.7 0.15 0.15 0.10

51 52.3 52.8 53.9 +0.7 -0.7 0.15 0.15 0.10

55 56.3 56.8 +0.7 -0.7 0.15 0.15 0.10

60 61.3 61.8 62.9 +0.7 -0.7 0.15 0.15 0.10

68 69.3 69.8 70.9 +0.7 -0.7 0.30 0.24 0.10

75 76.3 76.8 77.9 +0.7 -0.7 0.30 0.24 0.10

80 81.3 +0.7 -0.7 0.30 0.24 0.10

81 82.8 83.9 +0.7 -0.7 0.30 0.24 0.10

RMA*

* RMA = Rubber Manufacturers of America (also ANSI Standard)

• Always replace with like or higher design. – Different styles of belts may have the same dimensions, but mush

different horsepower characteristics.Replacing a B for a BX or a 5L with a B Belt will lead to:

Shorter belt life and continuing to install incorrect belt on drive.

• Never mix new and used of different manufacturers on the same drive.– Cord location is different and may result in shorter belt life

and maintenance issues with the unit.

Replacement Dynamics

FHP are: 8000 Hour

Design Life

Classical& 358 are:

25,000 Hour Design Life

Different Cross Section have Different Design Life & Different Horsepower Ratings

Belt Design Life:

Factors that can reduce belt life:Excessive sheave groove wear & improper alignmentLack of proper tension of the driveTemperature: High Ambient or from a process

Proper Drive Maintenance

Proper Maintenance Important

Poor Maintenance Cost Time!

Time is Money!

• Doing the same or more with fewer people!

Resources leave & don’t get replaced• Budgets getting cut!

Less money to do all the things in need to get done.• Looking for Higher Return on What I do get to spend!

Return on Investment to the Organization (ROI).

Safety First!• Always turn off and lock out power source. • Observe all other safety procedures.• Wear required protective gear or equipment, based

on site requirements.• Loss of production hours.• Critical System – Unscheduled downtime

What do you see once the belt guard is removed?

• Look at the drive elements – belts, sheaves, bearings

• Inspect belts for signs of failure:Glazing or cracked sidewallsUneven wear on sidewall of a beltExcessive belt dust

• Check sheave alignment

• Inspect sheave Even Groove wearBelts bottoming out

• Any bearing lubrication issuesExcessive heat

• Inspect the blower for other problems

Inspect the Drive

Belt DustingBelt Dusting

Inspect Sheaves on a regular basis

• Clean dirt or rust out of sheave grooveDirt and rust are abrasive to belt

• Inspect for damaged or worn groovesCheck wear with groove inspection tool or straight edge

The smaller sheave (Motor) will show wear first

Worn sheaves load on the end cords

higher, lead to rapid belt failure

and more frequent replacement

Belt should never ride in bottom of groove

Check for groove wear

>1/32”

Sheave Groove Wear

When do sheaves need replacing?

Check sheaves every time belts are changed.The smaller diameter sheave (usually the motor sheave) will

always wear out first, typically needs to be replaced with every 3rd or 4th belt change.

What happens with continued use of worn sheaves

• Loose adequate sheave sidewall contact. This can cause belts to slip causing excess friction & heat causing the belt to fail prematurely.Sheave walls become “dished” which reduces the ability of the V-Belt to wedge in the groove.

Less contact between the groove and belt surfaces.

• Reduced air flow for the blower unit. The smaller sheave will always wear out faster. In many cases this is the motor sheave, this will change the drive ratio & reduce air flow.

• Belt cords are un-evenly loaded.Not much different than using a new and used belt or 2 different manufacturers belts on the same drive. Just internal to the belt.

• Uneven wear on multiple groove sheaves can create uneven load sharing across all belts reducing efficiency and possibly creating vibration and noise.

Aligning Sheaves

4 point static contact with straight edge ensures alignment

4 point static contact per side when using cord or string

Can use a laser, but they are expensive, need to be maintained and take a some time when variable pitch sheaves are involved.

Misalignment & V-Belt Angle

Sheave should aligned within tolerance of specific style of belts:Wrapped Belts (FHP, A, B & 5V): ± 2˚ Notched Belts (AX, BX, 3VX & 5VX): ±1/2˚

There are 3 Basic Types of Sheave & Shaft Misalignment

How to correctly tension belts

+

Motor Blower

+

• The good old “Thumb Rule”Deflect the belt about ½ inch

• Too little tension the drive till the belt chirps on start up!This generates heat and will cause belts to fail prematurely

• Too much tension can over load the bearings!Excessive load can damage the motor and fan bearings

• Move the sheaves as close to the bearings as possibleReduce the cantilevered load on the shafts

This is what most technicians are using!

What should be using!

Accuracy and Consistency are Key!

Percent Slip

98%Optimal

82% Under-Tensioned

Energy loss from Belt slip(result of poor tensioning)

Under-tensioned V-belts slip which causes efficiency loss, premature belt wear and sometimes noise.

So why are Belts under tensioned?• Belts that are “rolled” onto the sheaves without adjusting the

motor base do not apply sufficient tension to prevent belt slip.Old belts are cuts off the drive and the motor base is not repositioned toward the blower the belt is forces over the rim of the sheaves.

This damages the cores of the belt and if a screwdriver or pry bar is used, could create nicks in the groove of the sheaves.

• Worn sheaves don’t provide adequate sheave sidewall contact. The belt are pulled deeper in the grooves providing less over all tension to the drive. Belts go slack after being run for a little while. When they seat themselves in the groove of the sheave.

• Replacing belts and moving the motor base back

to a “preset mark” does not ensure proper tension.

• Using an idler can help to apply tension but must be adjusted or re-adjusted to provide the proper force.

Double Check Belt HP Rating Verify motor nameplate HP rating

Example: 20HP @ 1760 RPM

Installing NEW Belts

Installing new belts:

Use all the same brand on the drive.

Never Pry Belts onto sheaves.

Energy Saving Opportunities

The Browning “Save the Green Campaign!”

HVAC Fan and Blowers

Proper Belt Tension – 10-15% loss if under-tensioned

Belt type – 3-5% gain by replacing wrapped V-Belts with raw edge V-Belts

Maintenance - 5-8% loss can occur due to Sheave wear

Ask to see our Energy Calculator that can run specific

application for horsepower and by state.

Energy Efficiency for Different Belt TypesWrapped vs. Raw Edge

• Raw edge cogged V-Belts provide a higher coefficient of friction with the sheave groove wall. This creates less slip when the belts are properly tensioned.– Raw edge belts directly replace

wrapped belts (BX48 replaces B48).

– Raw edge belts transmit more Hp than the equivalent wrapped belts.

– Raw edge belts provide better sheave groove wall contact than wrapped belts, even when used with smaller diameter sheaves.

Energy Loss from Worn Sheaves “As a sheave wears, the belt fits more loosely in the groove, so loads don’t transmit

as well. This causes an uneven load distribution across the belt tension member, with more load being applied at the belt edges. The effect is similar to that of high temperature.

Because of this uneven loading, worn sheaves reduce belt life by as much as 50%. But their adverse effect on efficiency is even more costly. The efficiency of a belt drive with visibly worn sheaves and loose, slipping belts can easily drop below 90%. To translate this into operating costs, consider a 50-hp belt-driven machine that costs $25,150 (at $0.07/kWh) to operate year-round. The efficiency loss due to loose, slipping belts and worn sheaves costs about $1,300 per year, more than enough to replace the belts and sheaves several times”. Power Transmission Design – June 1995

Neville W. Sachs, Salvaterra & Associates

Check for groove wear 1/32 “

Worn sheaves cause more load on the end cords – and more rapid failure

Sheave Groove Wear

Span = 32”

How to correctly tension a belt

• If belt span is 32” then a properly tensioned new V-belt should only deflect ½ inch when 8.0 lbs. of force is applied.

Deflection calculated: Span/64 in this example 32/64 = .5 or ½”• If deflection is greater than ½ inch, more tension must be

applied by adjusting the motor base.• Each drive is unique.• Move sheaves as close as possible to the bearings.

Reducing the overhung load &stresses on the bearings

+

Motor Blower

8.0lbs.

Energy Saving Program Part IIDrive Retrofitting

Gather Data

Retrofit Project:50 HP Supply Fan

• Existing Drive: 4 Groove C128 belt drive • Redesign: 2 Groove 5VX1400 v-belt drive• Energy Savings: = Over $1300 per year • Solution: Expensive MVP Sheave on the motor & Companion

Sheave on the Blower ALMOST 90% less than Existing Drive

Motor Sheave Cost: $2,276

Fan Sheave Cost: 1,113

Large Commercial Property Management Company

Total Sheave Cost: $3,390

Total Sheave Cost for Retro Fit: $ 3503 ½ Month - ROI

Retrofit Project –50 HP Supply Fan Cost Savings Example

• $959 per year in Energy Savings, using DOE 3% calculations• $2000 Sheave Replacement Cost Savings, comparing existing drive

to new drive• Extend Belt PM Cycle from 12 months to 30+ months, annual belt

cost alone is $340 – not including labor cost and time.

Existing (4) C120 Belt Drive New (2) 5VX1250 Belt Drive

What can be done to optimize drive life?

• Properly tension belts.Use a tool for consistency and accuracy.

Don’t use the “Rule of Thumb”.

• Check sheave for wear on a regular basis & replace worn sheaves.

• Always replace the existing belt with like or higher design. Upgrading belt design may even improve drive life.

• Make sure the drive in properly tensioned.

Sustaining Drive Efficiency

Promotes greater efficiency.

Compensates for variations in load

Compensation is obtained by combination of a one-piece movable carriage acted upon by a spring contained within the carriage

Carriage design promotes superior alignment

Auto Tensioning Motor BasesSpring Controlled Action

Offering

EFFICIENT LUBRICATIONOne GoldPlex™-SPL (EM) Can Service up to 8 Bearings

MODEL CAPACITY TEMPERATURERANGE

MAXIMUMDISCHARGEPRESSURE

MAXIMUMLUBE LINEDISTANCE

SPL-HP125-EM 4 fl. oz.(125cc)

-5F to 140F 300 PSI(20 bar)

30 feet(9 meters)

SPL-HP250-EM 8 fl. oz.(250cc)

-5F to 140F 300 PSI(20 bar)

30 feet(9 meters)

UNIT CONSTRUCTIONHigh Strength Polymer Design

GREASE CAPACITY125 cc or 250cc

UNIT INSPECTIONClear Top for Quick and Easy Inspection

CORROSION RESISTANCEGoldPlex-SPL (V) Unit Is Supplied With Clear Plastic Cover to Protect Variable Control Pad

GREASE TYPEFactory Filled with SealMaster GoldPlex™-HP Grease

VARIABLE CONTROL PADControl Pad Allows for Variable Lubricant Dispensing No Need for Activator Keys or Control Rings

SealMaster GoldPlex-SPL-EMSealMaster GoldPlex-SPL-EM

FEATURES & BENEFITS OPERATING RANGE

• (1) Replacement Grease Pouch 125cc or 250cc

• (1) Battery Pack

• (1) Disposable Dust Cover

Using Divider Blocks, One SPL-EM Lubricator Can Be Installed to Service up to 8 Ball or Roller Bearings. Consult PPP-04 Catalog Installation Kit Selection.

REPLACEABLE SERVICE PACK MULTI-BEARING CAPABILITY

Unlike the V Unit, The GoldPlex-SPL-EM Model Allows for Fresh Lubricant to Be Added when Unit Grease Bladder Has Been Depleted.

SPL-EM Divider Block

Accessories – (V Unit Installation Kit)Accessories – (V Unit Installation Kit)

Tools & Available Resources

Browning V-Belt Energy Efficiency Calculation I-Phone App

Viral Campaign with Facebook page and LinkedIn promotions

Magazine Ad Campaign centered around App Release committed

Compatible with I-Touch and I-Pad

Belt Efficiency Calculator APP

Browning Toolbox Technician APPWhere to Find Function

Connect With Us

Visit our Facebook page @BrowningBeltDrives 

Search Browning Belt Drives Save the Green. Join in on our belt drive conversations for energy savings and benefits.

Visit our website for: Application Engineering contact information, installation instructions, product interchange software www.emerson-ept.com.

Download the Browning Energy Efficiency Calculator for your iPhone® or Droid®. Search “Browning vbelts”

ThePowerTransmission for the latest product videos and trade show clips about Emerson Browning brand belt drive products and online tools.

Any Questions?

Contact Information