Presentation on theme: "V-Belt Drive Application Rick Stewart. Belt Drives on HVAC Equipment: Advantages, Terms, Belt Construction, Belt Length Variation, Replacement & Equipment."— Presentation transcript:
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 Resources Questions? & Contact Information WHAT WE WILL COVER:
Belt Drives on HVAC Equipment
Equipment Dynamics Traditional Center Distance Requirement (20-28 inches) New Center Distance Trend (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 % 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 & Horsepower Heat and Oil Resistant Static Conducting Low Vibration Low Maintenance Good for Shock Loads Wrapped Belt Cogged (Raw-Edge) Belt Fabric Polyester cords EPDM Cogged Belts: Transmit more horsepower Run cooler; Ave 16º to 30º Temperature Range -60º to +250º Slightly louder Need closer alignment
Belt Length Variation Standard Standard Datum Lengths PermissibleMatchingMatching Matching Length Cross Section Deviation fromLimits for Limits for Limits for Designation A,AX B,BX C,CX D Std. Datum LgthOne SetCode 1 Machine 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 alignment Lack of proper tension of the drive Temperature: 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 sidewalls Uneven wear on sidewall of a belt Excessive belt dust Check sheave alignment Inspect sheave Even Groove wear Belts bottoming out Any bearing lubrication issues Excessive heat Inspect the blower for other problems Inspect the Drive
Inspect Sheaves on a regular basis Clean dirt or rust out of sheave groove Dirt and rust are abrasive to belt Inspect for damaged or worn grooves Check 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 3 rd or 4 th 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 possible Reduce 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: 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 Types Wrapped 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 8.0 lbs.
Energy Saving Program Part II Drive Retrofitting
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: $ 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 Bases Spring Controlled Action
EFFICIENT LUBRICATION One GoldPlex™-SPL (EM) Can Service up to 8 Bearings UNIT CONSTRUCTION High Strength Polymer Design GREASE CAPACITY 125 cc or 250cc UNIT INSPECTION Clear Top for Quick and Easy Inspection CORROSION RESISTANCE GoldPlex-SPL (V) Unit Is Supplied With Clear Plastic Cover to Protect Variable Control Pad GREASE TYPE Factory Filled with SealMaster GoldPlex™-HP Grease VARIABLE CONTROL PAD Control Pad Allows for Variable Lubricant Dispensing No Need for Activator Keys or Control Rings SealMaster GoldPlex-SPL-EM FEATURES & BENEFITSOPERATING 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 PACKMULTI-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)
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 APP Where to Find Function
Connect With Us Visit our Facebook 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 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.