Technical Drawings and CAD Files

People often call to ask where they can get drawings of CAD files for our belts and sheaves. There are two places to look. The easiest is our online catalog:
www.gates.com/partview

By searching your part number in the top left, you can go directly to the product page. Each page has a general product overview with basic dimensions and information. A 2D spec sheet is usually available in the bottom of the "Attachments" section, and a 3D CAD model may be available to download near the top of the page.

If information is not available on PartView, you can find detailed sprocket specification tables in our drive design manuals. The manuals are broken down into belt lines such as Poly Chain GT Carbon, PowerGrip GT2 and Heavy Duty V-Belt. Small pitch (2, 3, 5mm) synchronous belts including PowerGrip GT2, HTD and Timing will be located in our Light Power and Precision Manual. All of these manuals are available to download along with our catalog here:
http://gates.com/catalogs/index.cfm?requesting=ptcatalog&location_id=2999

These manuals also contain horsepower ratings and many other great design and engineering resources.

Safety First

Gates publishes a detailed Preventive Maintenance manual, with strong content regarding safety practices.  Most of these are common sense - lock out the drive before touching the mechanical system, for example.

When working with any electrical power source, take extra care to make sure to avoid any hazardous situations.   Many years ago, during a power survey, I had a near miss when hooking up a data logger in the power supply box.   While I had many, many, experiences setting up the test equipment, this particular time I was shocked (literally) when clamping on an amperage probe.   I was very lucky - just a few hours of a numb arm and no lasting effects.

What is the point?   Never assume that the system is safe.  Ask, ask again, and double check to make sure every appropriate safety precaution has been properly taken before working on a belt drive system.  Accidents happen because people get in a hurry, or overlook the obvious, or make an improper assumption.  Remember - you're talking about your health - act accordingly and be mindful of the proper safety measures when doing any installation or maintenance work.

Finding NEMA

If you are using an electric motor to run your belt drives and are having problems with the life of the bearings and/or shafts, your motor pulley may be smaller than recommended. As the pulley size on the motor decreases, the magnitude of the belt pull increases, thus exerting a higher load on the bearings and shafts of the motor. NEMA (National Electrical Manufacturers Association) issues a list of minimum recommended sizes for various NEMA frame electric motors. Staying above these values should extend the life of the bearings and shafts on the motor and should prevent any premature failures from occurring. Below is the NEMA table taken out of the Gates Polychain Carbon Drive Design Manual:

These standards can be found on the NEMA website at http://www.nema.org/, or in any of the Gates Drive Design Manuals found at www.gates.com/partview

What Belt Length Do I Need?

One of the most common questions we get is: “What belt length do I need?” Well, there are a couple of ways to figure this out. First, lets do it the hard way. You can use the equation:

Lp = 2C + 1.57(D + d) + ((D – d)^2 / 4C)

Where:
Lp = belt pitch length, inches
D = diameter of large sprocket, inches
D = diameter of small sprocket, inches
C = center distance, inches

Now if doing the math isn’t for you, there are a couple of easier ways to get this figured out. I would recommend our free software. We offer both Design Flex (Web and Pro versions), and Design IQ. You can download either of these at www.gates.com/drivedesign Design Flex is a two point drive design program that is tailored to help you easily design drives, and find proper tension. Design IQ is a little more complex; it is designed to help with drives no matter how many sprockets or sheaves.

With Design Flex, you will need to enter in a load in order to get it to calculate a belt length. While this load doesn’t need to be accurate for calculating belt length, you do need proper loading for trying to design or find the correct tension for a given drive.

With Design IQ, you don’t need to enter a load to get a belt length, but you need to understand where you are placing the sprockets/sheaves. Starting with the driver at the coordinates (0,0), place the driven at the measured center distance in the X coordinate and 0 in the Y coordinate, you can easily find the two belt lengths that are closest (one shorter, and one longer) by selecting the belt length button. When you select one of the belt lengths, the program will then show you what your actual center distance will be in the driven sprockets/sheave’s X coordinate box.

As always, if you have any questions, or would like us to walk you through an example of how to do this, you can call us at 303-744-5800.

Design Flex Force/Deflection Tensioning

We often get questions from customers about the force/deflection tensioning recommendations on a Design Flex printout. The report lists the "Rib/Strand Deflection Distance" and the "Rib/Strand Deflection Force" for both a new and used belt. If you have never used this method of measuring tension, our Belt Drive Preventive Maintenance and Safety Manual has thorough instructions.

Some people think that you can measure the tension by only measuring deflection. However, in order to properly tension a belt, you must measure both the force and deflection distance. Measuring one inch of deflection with 5lbs of force is a very different tension than one inch of deflection that requires 100lbs of force.

Some confusion arises from the "Rib/Strand" portion of the title. For a synchronous drive, there is almost always only one belt, so you can use the listed force/deflection values. V-belts however, often have more than one belt on the same drive. In order to properly tension the drive you must multiply the deflection force by the number of strands that you will be deflecting. Even though your PowerBand belt looks like a single belt, you must multiply the force by the number of ribs. The deflection distance is not multiplied by the number of ribs and is calculated as 1/64 of an inch per inch of span length.

People also wonder what is considered to be a used belt. Any belt that has not been run more than about 24 hours is considered a new belt. If you are reassembling a drive with the same belt that was used previously, it is recommended that you measure the tension before dis-assembly and reinstall it at the same tension. If you did not measure the tension, you can reinstall with the used belt values.

Minimizing Noise In Synchronous Belt Drive Systems

Drive noise evaluation in any belt drive system should be approached with care. There are many potential sources of noise in systems including vibration from related components, bearings, and resonance and amplification through framework and panels. Belt drives sometimes receive blame from noise generation that they don't actually produce.

Noise from synchronous belt drive systems generally results from the process of belt tooth meshing and physical contact with sprockets. The sound pressure level generally increases as operating speed and belt width increases, and as sprocket diameter decreases. Drives designed with moderate sprocket sizes and without excessive capacity (over-design) are generally the quietest.

Proper belt installation tension is very important in minimizing drive noise. Belts should be tensioned at a level that allows them to run with as little meshing interference as possible.

Drive alignment also has a significant effect on drive noise. Special attention should be given to minimizing angular misalignment (shaft parallelism). This assures that belt teeth are loaded uniformly and minimizes side tracking forces against the flanges. Parallel misalignment (sprocket offset) is not as critical of a concern so long as belts are not trapped or pinched between opposite flanges.

Gates Supports FIRST Robotics 2011 Preseason

Gates is offering free 2011 preseason belt drive components to all interested FIRST Robotics teams. To help teams determine what parts may be needed, Gates has free drive design manuals and design software available at www.gates.com/drivedesign/.

To order parts, first fill out the form at http://www.usfirst.org/roboticsprograms/frc/content.aspx?id=18398 then email the completed form to ptpasupport@gates.com. Please include the team name, number, and the word FIRST in the email subject.

Parts will be ground shipped to the address provided on the form free of charge. The deadline for submitting orders is December 15, 2010.

If you have any questions, please contact Gates Product Application Engineering at 303-744-5800 (Option 2) or email ptpasupport@gates.com. Gates reserves the right to limit the style and quantity of parts provided to each team.

Measuring Efficiency - An Average Value in an Instantaneous World

We publish that converting from V-belts  to synchronous belts will save an average of 5% of the drive's energy consumption.   Sometimes this can be confused with measurements taken to confirm energy savings by end users.  

Note that the 5% is an average estimate.

Both highlighted words at the end of that sentence need further explanation.

The savings is an average value because the savings comes over time.  Newly installed and properly tensioned V-belts running in good sheaves are going to be very efficient.  Comparing a newly installed synchronous belt drive with an instantaneous measurement to a newly installed and properly tensioned V-belt drive, or a newly re-tensioned V-belt drive will most likely only show a couple of % difference in energy savings for the synchronous belt drive.

Average is just that - an average over time that demonstrates not only the reduced bending stresses and cooler operation of synchronous belts, but also the natural trend of increased slip and creep of V-belt drives...over time.  An average value isn't a guarantee of a minimum 5% performance increase, but is an average over time.

If an attempt is made to measure efficiency gains, that measurement is only a small slice of the average total result.   Its an instant out of the entire operating period, and not representative of the overall efficiency gain.

The savings are also quoted as an estimate.   This is done because every drive and circumstance is different.  The savings gain from a conversion of poorly maintained systems will most likely exceed 5%.  The savings from converting a well maintained system may not achieve 5% savings.  Systems that are redesigned to use the consistent speed of a synchronous belt drive can more accurately run at speeds that are actually needed to do the work required may  have dramatically higher savings.   Extensive field tests, confirmed by laboratory testing, has confirmed that the estimate, of average savings, is reasonable to use at 5%.

So - keep the above in mind when discussing or handling the energy efficiency issue.   Don't use an estimated average value to guarantee a minimum instantaneous expectation.

 

HTD Does Not Stand for Synchronous

A lot of people associate the acronym HTD with synchronous belts. While there is good reason for this, most take it a little too far, and believe that HTD refers to all synchronous belts. This is not the case. HTD stands for High Torque Drive, and calls out a specific tooth profile. This type of profile is called a curvilinear profile. An HTD tooth form looks like a half circle. Other curvilinear profiles are available today as well, including our GT profile. Here at Gates, we replaced our main 8mm and 14mm HTD belt lines with our GT tooth form quite a number of years back. HTD is still offered stock in 3mm, 5mm, and 20mm pitch belts, but not in our 8mm and 14mm lines.

Some of our competitors still offer off the shelf 8mm and 14mm pitch belts and sprockets. This causes questions about interchangeability. When we designed our GT tooth form for 8mm and 14mm pitch, we designed the belts to be able to drop into the old HTD sprockets. This is a one way replacement; you cannot drop an HTD belt into our GT sprockets. The HTD tooth is wider than that of our GT belts. Also, this drop in ability is only for the 8 and 14mm pitch belts, not for the smaller 3 and 5mm pitch.

There are reasons why one would still want to use HTD in 8mm and 14mm belts today, and it's possible with special order belts. Keep in mind though, special order means lead times and minimum order quantities. If you have a standard industrial application, it's likely it will be alright to switch to GT. If you have a specialty drive such as a supercharger on a car, you may want to call us to be sure.

For more interchange information, check out our Belt/Sprocket Interchange Guide. You can download your free copy at www.gates.com/drivedesign Click the link to Drive Design Manuals, and scroll down until you find it (you will have to register if you haven't previously done so).

Belt Drives And Vibration

Some ultra-sensitive applications require belt drives to operate with as little vibration as possible, as vibration sometimes has an effect on the system operation or finished manufactured product. In these cases, the characteristics and properties of all appropriate belt drive products should be reviewed. The final drive system selection should be based upon the most critical design requirements, and may require some compromise.

Vibration is not generally considered to be a problem with synchronous belt drives. Low levels of vibration typically result from the process of tooth meshing and/or as a result of their high tensile modulus properties. Vibration resulting from tooth meshing is a normal characteristic of synchronous belt drives, and cannot be completely eliminated. It can be minimized by avoiding small sprocket diameters, and instead choosing moderate sizes. The dimensional accuracy of the sprockets also influences tooth meshing quality. Additionally, the installation tension has an impact on meshing quality.

PowerGrip® GT®2 drives mesh very cleanly, resulting in the smoothest possible operation. Vibration resulting from high tensile modulus can be a function of sprocket quality. Radial run out causes belt tension variation with each sprocket revolution. V-belt sheaves are also manufactured with some radial run out, but V-belts have a lower tensile modulus resulting in less belt tension variation. The high tensile modulus found in synchronous belts is necessary to maintain proper pitch under load.

PowerBand® Joined V-Belts

PowerBand V-belts are multiple Gates V-belts that are joined with a single backing. PowerBand V-belts provide the following advantages (compared to single V-belts):

• They are more latterly rigid, making them more stable on drives with pulsating or heavy shock loads. This makes them less likely to flip over or jump off a drive.
• The single belt design promotes uniform loading.

PowerBand V-belts can carry the same load as an equivalent number of single V-belts. For more information on the Gates family of PowerBands belts, visit http://www.gates.com/brochure.cfm?brochure=2921&location_id=3102

CenterTrack

Gates Carbon Drive has just released its newest innovation; CenterTrack. The new system from Carbon Drive (the branch of Gates responsible for replacing roller chain on bicycles with a specially designed Poly Chain belt) is a leap forward in bicycle drive technology. The feature that separates this drive from the previous drive is the flange that runs down the center of the sprocket. This makes the system lighter, and narrower, while still maintaining the benefits of a belt drive such as its debris shedding capability, smoothness, lack of stretch, and cleanliness. Because the sprockets can be narrower, the drive can be integrated on frames and internally geared hubs where previously it would not fit, opening up even more options for the consumer. The belt itself only changes by receiving a small slit cut through the teeth of the belt. This doesn't affect the performance of the belt, because great care is taken to keep the slit from reaching the carbon cords inside the belt. For more information, and for images, check out the Gates Carbon Drive Blog site at: http://blog.carbondrivesystems.com/?p=740

How Adjustable Are You?

When designing a belt drive, one important feature you always need to keep in the back of your mind is how you will be applying tension to the belt. If you have two fixed shafts, you will need an idler assembly. If your center distance is adjustable, you will need to know how much adjustment you have. Fixed center distance without adjustment or idlers have worked in the past, but success stories are rare and this type of belt drive set-up is not recommended.

Anytime a Gates Engineer designs a belt drive for you, you will get a theoretical center distance and also an install/take-up range. What do these mean you ask?

• An installation distance is the center distance we recommend your shafts be able to achieve in order for proper installation without issues. If you don't have the available installation distance for your belt during the installation process than your belt will seem like it's too short for the center distance you measured. This can lead to forcing the belt onto the pulleys which can be damaging for the belt and pulleys.
• A take up distance is the center distance we recommend your shafts be able to achieve in order to maintain proper tension on the belt throughout the life of the belt. If you don't have the available take up distance then your belt can become loose which can lead to premature failures.

Each belt line has a different installation and take-up range because they all have different length and stretching properties. If you don't know what your belts installation and take-up range is than you can use one of Gate's drive design programs (DesignFlex or Design IQ) to calculate it, or you can calculate it yourself by looking up the equations in the appropriate Gates Drive Design Manual. Gate's drive design programs and drive design manuals are available on the website at www.gates.com/drivedesign.

Measure Twice, Cut Once

True, the old adage "measure twice, cut once" applies directly to carpentry and not to belt drive design, but there is some truth in the saying that designers should pay attention to.

When designing a replacement or retrofit synchronous belt drive for a piece of equipment currently using a V-belt drive, it is recommended that the actual operating shaft speeds be measured instead of just basing the new synchronous belt drive design on the existing V-belt sheave diameters.

Why?

Glad you asked!

V-belts will slip, from little (well maintained) to a fair amount (if poorly maintained, or running in worn sheave grooves).   It is very easy to make significant errors in the driveN shaft design speed if you assume that the V-belt drive is operating at exactly the ratio as calculated by the sheave diameter ratio.  Good practice is to always measure the shaft speeds - with either a contact or strobe tachometer.

This is of extra importance when designing a drive to operate on fans or centrifugal pumps - where the driveN load characteristic is sensitive to operating speed.

High Speed - Small Pitch Drive Applications

Synchronous belt drives are often used in high speed applications even though V-belt drives are typically better suited. They are often used because of their positive driving characteristic (no creep or slip), and because they require minimal maintenance (minimal stretch). A significant drawback of high speed synchronous drives is drive noise. High speed synchronous drives will nearly always produce more noise than V-belt drives. Small pitch synchronous drives operating at speeds in excess of 1300 ft/min (6.6 m/s) are considered to be high speed.

Special considerations should be given to high speed drive designs, as a number of factors can significantly influence belt performance. Cord fatigue and belt tooth wear are the two most significant factors that must be controlled to ensure success. Moderate sprocket diameters should be used to reduce the rate of cord flex fatigue. Designing with a smaller pitch belt will often provide better cord flex fatigue characteristics than a larger pitch belt. PowerGrip GT2 is especially well suited for high speed drives because of its excellent belt tooth entry/exit characteristics. Smooth interaction between the belt tooth and sprocket groove minimizes wear and noise. Belt installation tension is especially critical with high speed drives. Low belt tension allows the belt to ride out of the driven sprocket resulting in rapid belt tooth and sprocket groove wear.

Gates Can Help You Select the Perfect Belt for Your Application

Do you want help designing a belt drive for your application?

Are you wondering which Gates belt will work best for your application?

Do you have technical belt questions that you can't find answers for?

Gates belt application engineers are here to help you!

Gates application engineers are available to assist you Monday through Friday, 7:00-11:00 am and 12:00 pm-4:00 pm MST.

You can talk to a Gates application engineer by calling 303-744-5800, option 2. Application engineers may also be contacted via email at ptpasupport@gates.com.

Understanding Power: Power Factor, Apparent/Reactive/Real Power

In order to understand energy and the efficiency gains made possible by synchronous belt drives, it is important that four terms be explained and their relationship to each other defined. Those four terms are apparent power, reactive power, real power, and power factor.


Apparent power is the total power supplied by the utility company to the end user’s facility. Apparent power is measured in kiloVolt Amperes (kVA). This power is comprised of 2 components - reactive power and real power.

Reactive power is measured in kilovolt Amperes Reactive (kVAR). For power transmission purposes, we are dealing primarily with electric motors. Reactive power is the non-working power necessary to create the magnetic field in an electric motor. Some facilities utilize capacitors in their electrical system to reduce the amount of reactive power required. Depending on the size of the end user, his power demands, and the limitations of the local utility company, capacitance correction can be “encouraged” by the utility company. This “encouragement” typically takes the form of a penalty if the utility company feels that the facility is requiring too much reactive power (and total apparent power as a result). Remember that since it is not included in their billing, reactive power is of no interest to the end user. Only the utility company is concerned with reactive power. Since reactive power is part of the power supplied by the utility company, it must also be accounted for in the utility company’s power generation capacity. By forcing users to control reactive power, utility companies can stretch their resources.

Real power is the power paid for by the end user, and is measured in kiloWatts (kW). Real power is also the power that can be reduced by converting V-belt drives to synchronous belt drives and utilizing the mechanical efficiency advantages of a positive drive. Real power is the component of the power supplied by the utility company that actually does useful work. Utility customers are actually billed for kiloWatt-Hour
(kW-Hr) usage, a typical energy value.

Power factor is simply the ratio of real power to apparent power. Utility companies prefer high power factors (over .90) since that results in a lower reactive power and thus a lower total apparent power that they must supply. However, this tends to run opposite of the effects of energy saving devices at the output of electrical motors. Anytime load is reduced on the motor (by increasing the efficiency of the power transmission system, or increasing the driveN equipment efficiency), the power factor will drop. In order for electric motors to operate at a high power factor, they must be loaded to their full capacity. Motors operating at loads less than 100% will see corresponding drops in power factors.

The real power being used for work and paid for by the end user is basically calculated by multiplying the power factor, voltage (volts), and current (amperes) together. In order to reduce the real power (kW) being consumed, the end user must therefore reduce either the power factor, the voltage, or the current (or any combination of the three). Energy savings measurements performed using a computer data logger system have shown that conversions to synchronous belt drives from V-belt drives rarely result in a voltage reduction. Small savings in amperage have been noted, but are typically small enough to be undetectable by ordinary clamp-on ammeters. The primary savings in real power (kW) usage is in power factor reduction. This has been demonstrated on every successful conversion that has been measured, and is an expected occurrence. The characteristics of electric motors demands that the power factor decline as the power demands decline.

The final result is that when looking at the bottom line - energy being paid for by the end user (kW-Hrs) - synchronous belt drives do result in energy savings. Field testing has proven that the 5% energy savings claim is valid, and in many cases conservative. For a thorough energy savings evaluation, it is necessary to use equipment which measures all of the components of energy usage: time, current, voltage, and power factor. Without measuring all of the components, an incomplete picture of the energy usage is provided. Common hand held instruments (ammeter, voltmeter) are insufficient by themselves to document energy savings. If an installation must be surveyed for energy usage, equipment which has the ability to measure all four components of energy usage (such as a data logger) must be used.

Gates Engineering Website

If you are looking for a place where you can find technical information regarding Gate's industrial belt drive products, try logging on to www.gates.com/drivedesign. Here you can find all of the industrial power transmission resources consolodated into one location. Content on this site includes:

• Case Studies


• Drive Design Programs


• Catalogs


• Drive Design Manuals


• Installation Tools


• Gates Facts


• White Papers & Notes

Torpedalo Project

Ever think about crossing the Atlantic Ocean in a human powered craft? This is exactly what Mark Byass and Mike Sayer in the UK are planning to do for charity in a special pedal powered boat that they are designing. As engineers, they are designing the boat to be entirely self-sufficient with onboard electricity generation and water production. The planned duration for the 3000 mile journey is only 38 days. Mark and Mike will be rotating 12 hour shifts on the pedals, and their power will hopefully be transmitted to the propeller and on board support equipment via. belt drive systems. Preliminary belt drive designs are currently being reviewed and refined, and one will likely incorporate an unusual 90 degree twist. Belt drive systems are efficient, reliable, and quiet making them an ideal choice for this unique and demanding application. Read more about this exciting project at www.torpedalo.com.

Details Needed for Belt Drive Selection

One of the valuable services offered by Gates Application Engineers is assistance with belt drive selection. However, many requests do not contain all of the information needed for proper design and evaluation. When you call or email an application, please include the following details:

1. A description of the application (fan, pump, conveyor, etc.)
2. The hours per day that the drive will operate
3. DriveR rpm and horsepower/torque rating
4. DriveN machine speed or required speed ratio
5. Approximate center distance required
6. Shaft diameters (if available)
7. Any space restrictions
8. Any environmental concerns (oil, high temperatures, etc)

For more complex drives involving idlers, multiple driveNs, or special duty cycles, additional information may be needed.

NHRA Supercharger Drives

NHRA supercharger drives are notoriously hard for belts to survive on.  The application is extremely demanding, and requires a unique belt to perform as needed.   The two top classes that use superchargers are Top Fuel and Funny Car.  In a typical 1000 foot race, a Top Fuel car will have elapsed times in the 3.8 to 3.9 second range.

HP requirements to drive the supercharger are typically quoted in the 800 HP to 1000 HP range.  This is with the driving crankshaft being around 8000 - 9000 RPM.

If it was just a question of handling 800 to 100 HP, the drive (while large), wouldn't be that difficult to design to work properly.  However, the system has a lot of unique load situations that really stress the belt.  The torque  fluctuations from the engine resemble barely controlled explosions.  The speeds are high.  The heavy loads make it likely that shafts will flex and belts will track to the outside flange edge.  During tire spin conditions, drivers have to "pedal" the car.  This is a method of getting off and back on the throttle very rapidly in an attempt to get the tires hooked up and stop the tire spin.  When this happens, the driving RPM drops nearly instantly from 8000+ RPM to a couple of thousand RPM.  The inertia of the supercharger takes over at that point and it tries to become the driving shaft.  This creates havoc in the belt, as the tight and slack side spans in the system are reversed, creating high shock and compressive loads in the tensile cord.  Add in the virtually instantaneous load application when the cars leave the starting line, and you have a very difficult, very damaging application.

An 11mm pitch Poly Chain GT belt was specifically designed for this application.  The 11mm pitch gives more speed ratio flexibility than the previous 14mm pitch belts, and 11mm belts have more strength and ratchet resistance than 8mm pitch belts.   A specially designed tensile cord is also used to handle the loading situations described above.

Add all that together, and you have the situation you'll see on any typical weekend NHRA race.  Top Fuel and Funny Cars going down the track, round after round, reliably.   Its one of the 7 belt wonders of the world.

Belt Profiling

If you know anything about synchronous belts you'll know that belts come in different sizes. This can mean different widths, lengths, and pitches (spacing between teeth). So if you know these three dimensions of a belt it means you can go to the store and pick up a new one right? Wrong. One other important characteristic you need to know about a synchronous belt is the tooth profile.

The tooth profile is going to identify the shape of the tooth whether it's flat, round, or a combination of both. Industry profile standards were created for belt manufacturers to simplify the process of designating a belt type. For example "Timing belts" have flat or trapezoidal teeth where "HTD belts" have round teeth. As technology has advanced, so too has the synchronous belt tooth profile. Multiple variations of tooth profiles have emerged from different manufacturers such as GT, RPP, HTD, and STPD profiles, as seen below.

Because of the difference in shape amongst the profiles, not all belt tooth profiles work in each others sprocket grooves. This is one very common mistake made with synchronous belt drives. A belt is replaced with another one that has a different tooth profile and it fails much faster than the previous belt. This is because the tooth is not sitting into the sprocket grooves properly so it's not transmitting the load as it was designed to.

Now this doesn't mean that two different belts are never compatible with each other. There are actually quite a few that you can use as drop in replacements for one another, but you need to know which ones will work and which ones wont. Gates has published a catalog just for this problem called the Belt/Sprocket Interchange Guide. In the guide you can look up which belts will work in different sprocket configurations and which ones will not with a description of why or why not. Of course its always recommended to use the belt that matches the sprocket grooves, but sometimes this will not be an option. The Gates Belt/Sprocket Interchange Guide can be found online at www.gates.com/drivedesign.

Gates Carbon Drive

In a previous post, I had mentioned Gates Carbon Drive for bicycles. I’d like to give you a little bit more information about this great product. As a quick recap, the Gates Carbon Drive system is two sprockets and a belt. The belt is a version of our market leading Poly Chain Carbon belt. This is a polyurethane belt with carbon fiber tensile members. The bicycle belt has been optimized for operation on bicycles, and the sprockets are very specific, lightweight, machined parts. In fact, the sprockets are made to bolt directly on to existing bicycle components. Now a very important fact to mention is that while the sprockets can bolt on to stock components, most bicycle frames require the chain to pass through a rear triangle to get to the rear wheel. Because the Poly Chain belt cannot be broken and reconnected, there has to be a gap in the frame for the belt to pass through. This makes retrofitting the system almost impossible for most consumers. While this is unfortunate, there is a big light at the end of the tunnel. Because this product is a revolution in this market, bicycle manufacturers such as Trek, Specialized, Norco, etc… have jumped on board, and are building frames made specifically to accept the Gates Carbon Drive. These frames have both the break in the rear triangle that is needed, as well as an adjustment to add proper tension to the belt. Now if you are familiar with belt drives, you probably know that as important as tension is, alignment is just as important for proper operation. This means that the belt cannot be derailed, which makes typical shifting on a bicycle through a derailleur impossible. The good news is that the world of internally geared hubs is growing quickly. An internally geared hub is a rear hub that uses gearing on the inside of the hub to offer several different final drive options. Some of the more common hubs are offered in 3, 7, and 8 speeds. This means that the Gates Carbon Drive system has options for gearing on bicycles.

Now we covered a bit on installation, and a bit on gearing options. Your next question may be “so what is the benefit of a belt to a chain?” Well the answers are not that different from the reasons you would use a belt in the industrial market. The belt is clean, it doesn’t need to be lubricated, it doesn’t stretch - therefore reducing maintenance time, it doesn’t rust, it lasts longer than chain, it’s quiet, smooth, and light weight. These characteristics make it ideal for your average bicycle commuter; think about it, the belt isn’t greasy, doesn’t need to be adjusted once set up, doesn’t have a problem with the elements, and lasts longer. This doesn’t mean that it doesn’t work for other applications. Our patented Mud Ports (holes in the bottom of the sprocket groove) shed dirt, rocks, and snow like nobody’s business. This makes the system viable for mountain bikes as well.

Hopefully this post has given you enough background information to spark your interest in Gates Carbon Drive. To see our product line, and to find a listing of current manufactures and models offering the Gates Carbon Drive, please visit www.carbondrivesystems.com Hope to see you out there!

Bigger is Not Better – Overdesign Impacts Performance

A common perception with industrial belt drive designs is that belt drives with greater load capacity will always outperform those with less load capacity. While this may seem logical , implementing grossly over-designed drives can actually reduce overall performance. “Bigger” is not always “better”. When designing industrial belt drive systems, remember to check rated drive load capacities against design loads. Confirm that over-design ratios are not excessive. Over-design ratios should not typically exceed 2.0 for both synchronous and V-belt drives. For over-designed belt drive systems, re-calculate belt installation tension levels based on rated drive load capacity to improve belt performance or re-design for appropriate load capacity.

If you don’t know about Gates Carbon Drive for bicycles, here is your chance. We will be attending the Lyons-Boulder Centurion Cycling Event on July 18th. The Centurion is three events in one; a 100, 50, and 25mile ride; all types are encouraged, from seasoned racers to families. We here at Gates intend to have riders in at least two of the three categories equipped with different types of bicycles, each sporting the Gates Carbon Drive system.

What is the Gates Carbon Drive system? The system is basically two sprockets and a belt that replace a chain and chain sprockets on a bicycle. The belt is a version of our market leading Poly Chain GT Carbon belt that has been optimized for power transmission on bicycles. The sprockets are designed to mount on bicycles using standard bicycle components. We will get more into the technical aspects of the bicycle components in a later post. In the mean time, come check out some of the Gates crew at the Centurion, and demo ride a bicycle with Gates Carbon Drive!

http://www.centurioncycling.com/

www.carbondrivesystems.com

Hospitals and Energy Savings (or "Watts Happening")

Energy consumption continues to rise as the population grows.  An example of this is the staggering cost of energy to healthcare organizations - an enormous $8.5 BILLION spent on energy every year.

Up to 3% of an average hospital's budget is spent on energy.  This works out to around $5.25 per square foot.  (Source:  Energy Information Administration, Commercial Buildings Energy Consumption Survey 2003).  As energy usage continues to increase, so does the cost of energy to the facilities.  Over 90% of hospitals reported an increase in energy costs over the previous year.

A recent survey ( American Hospital Association Annual Survey) showed that $1 saved on energy at a hospital has the equivalent impact on the bottom line as increasing hospital revenues by $20. 

Clearly, there are obvious benefits to hospitals and healthcare facilities for reducing energy consumption.

Synchronous belts and molded notch V-belts are natural candidates to implement on belt drive systems to save energy.  V-belt drives can be converted to synchronous belt drives to save approximately 5% on energy as well as virtually eliminating maintenance requirements.  Molded notch V-belts can save approximately 2% on energy if used to replace traditional banded V-belts.

Its clear that energy consumption and savings efforts are here to stay.   Use the available belt technology to get some easy savings and you'll be ahead of the game.

Sonic Tension Meter 507C

The Gate's Sonic Tension Meter 507C is an electronic device that measures the static tension in a belt by analyzing the harmonic characterisitcs of the belt when its vibrating. Belts, like strings, vibrate at a particular natural frequency based on the mass, span length, width, and tension. The 507C measures this natrual frequency and converts it to a static tension force.






How it works:

First, the belt mass constant, belt width, and measured span length are entered into the meter. Next, hold the meter sensor to the belt span, then lightly stum the belt to make it vibrate. Press the "measure" button to obtain the reading in either herts (Hz), kilograms (kg), pounds (lbs) or Newtons (N).

Features for the meter include:

• Output readings measurable in hertz (Hz), kilograms (kg), pounds (lbs) or Newtons (N).
• Frequency range from 10 - 5000 hertz.
• Variable frequency range filters
• Auto gain conrol automatically adjust meter sensivity.
• 20 memory registers for belt constants.
• LCD screen with back light.
  

Aside from the standard sensor, an optional flexible sensor for hard to reach areas and a magnetic inductive sensor for loud environments are also available.

Design Manuals and Software

We here in the Product Application Department (the Marketing Department as well - share the love) are finishing up a major revision of a product drive design manual that should hopefully be released shortly.  Going through revisions of a print catalog prompted the thought - "Do users of this catalog know they can download software to do these calculations instead of doing them manually?". 

Gates has 2 main industrial drive design software packages - Design Flex Pro and Design IQ.  

Design Flex Pro is intended for users to design simple 2 shaft drives, and automate the process that is contained in the drive design manuals.  Instead of taking an hour or more to design a single drive out of a drive design manual, a user can design literally dozens of drives in less than a minute.   Design Flex Pro also allows users to optimize their selection based on specific application needs (center distance, driveN RPM, belt pull, etc.). 

Design IQ is intended for users to design more complex multiple shaft drives.  Users will most likely need to be a bit more experienced in belt drive design to initially use Design IQ, but the program is not difficult to use.  In comparing the two software tools, Design FlexPro is a hammer, and Design IQ is a scalpel.  

You don't build a house with a scalpel, and you don't want your surgeon using a 20 ounce framing hammer when he's performing a quadruple bypass.   Pick the right tool for the right job.  

Both software programs are available for download at:

http://www.gates.com/designflex/index.cfm?location_id=809

http://www.gates.com/designiq/index.cfm?location_id=11292

Predator V-belt Matching

Predator® V-belts contain kevlar tensile cords, which stretch only a minor amount. Therefore, multiple Predator belts that are not the same length will not "equalize" during the run-in period. So, to ensure that the belts properly share the load, Predator belts should be ordered with the same group (or punch) number.

The photos below illustrate the location of the group (or punch) number. The number will be stamped in gold color next to the transfer label on the Predator belt or next to the content label in black ink on the outside of the carton.

Flat Flexible Sensor for the Gates Sonic Tension Meter

Gates is now offering a new flexible sensor (7420-0205) for use with the Sonic Tension Meter 507C. The new flat (paddle-type) sensor replaces the discontinued round flexible sensor (7420-0204).

The new paddle-type sensor offers:

• Increased durability
• Increased flexibility
• Comparable microphone sensitivity and response
• Reduced clearance requirements (due to the flat sensor's ability to pick up sound from the sides instead of the end)

For more information on the Gates Sonic Tension Meter and accessories, please visit www.gates.com/stm/.

When Should Belts be Replaced?

There isn't a standard interval for belt replacement. A well-designed belt drive may last for months or years depending on the specifics of the application. Many factors influence belt life, including actual loads, belt installation tension levels, drive alignment, sheave condition, environmental conditions (chemicals, abrasives, temperatures, humidity, etc.), product manufacturing variations, etc.

The best way to determine a replacement interval for your particular drives is to look at old maintenance records (if they exist). If there seems to be a common point at which belts fail, reducing this number by approximately 30% should provide a good replacement interval.

Periodic inspections of the belt drive (every 3 - 6 months depending on how critical the application is) will also help to determine when the belts need to be replaced. More information on drive inspection is available in the Belt Drive Preventive Maintenance & Safety Manual at http://www.gates.com/brochure.cfm?brochure=1224&location_id=3288/.

Gates FIRST Robotics Scholarship

Gates is offering up to three $2000 scholarships for seniors that participated in the 2010 FIRST Robotics competition and used a Gates belt drive component on their competition robot. These are merit based scholarships, and require that students answer one of two "challenge" questions posed in the application. One challenge question is straightforward and asks students to explain how a belt can be used to transfer energy from a common power source. The other challenge question provides a situation in which the students have creative license on how to solve a problem using belts. Gates feels that with the option of two questions, students have the ability to approach the application in a creative manner that suits them best, and showcases their ingenuity to Gates. For more information on the scholarship, please visit www.gates.com/FIRST .

Gates PartView

Gate's PartView is a website dedicated to providing modeling resources and part specifications for anybody who can access the internet. Partview can be easily accessed by logging on to www.gates.com/partview. Information such as belt and sprocket dimensions, part numbers, materials, and properties such as oil & heat resistance and static conductivity are all listed on Partview. CAD models in a variety of formats such as Solidworks, AutoCAD, and Pro/Engineer are also available for selected parts.

What Not to Do!

As a product application engineering department, we see some unusual uses of belts - not always correctly used! 

In the photos below, see if you can identify what is wrong with the application in the picture.

Give up?

Those are synchronous sprockets, with a V-belt installed to transmit power!  An application engineer was visiting a customer site and ran across this "creative" use of mismatched components.  Best guess is that originally the V-belt was installed because a replacement synchronous belt wasn't on hand, and it worked "good enough" that they never went back and used the proper components.

Obviously - NOT RECOMMENDED!

Many years ago, a farmer called the Product Application department with a question about what nail size he should use - 8d, 10d - he didn't know for sure.  A confused application engineer asked him what he was talking about - you don't use nails on a belt drive.   The farmer replied that he was rebuilding a windmill to get water to his livestock, and all he wanted to know was what size nails the synchronous belt needed to run on.  Even more confused, the engineer pressed for more details....turns out that the farmer was planning on making his own sprockets by welding nails between two steel plates and needed to know the nail size that would best fit in the belt teeth to act as the sprocket teeth!

Sometimes you learn what to do correctly by seeing things that are done incorrectly.....

PA Notes

PA Notes are technical documents written by the Product Application department that are intended to address particular technical issues or design matters for Gates users and customers.  The very first PA Note, Volume 1, Number 1 was issued on August 29, 1951.   The current PA Note content is up to Volume 57.

Its interesting to look back at that first PA Note and see the content and the state of the art for belt power transmission in 1951.  Topics included in Volume 1, Number 1:

1)  The use of a V-flat drive on a generator.   (When was the last time you designed a flat belt drive?  In fact, when was the last time you saw a flat belt drive?)

2)  Designing a flat belt drive on a turbine application.  (Flat belts were the belt of choice for high speed applications "back in the day".  Now, we would instead design with Micro-V or Polyflex V-belts.   Belt technology has come a long way.)

Consider how long that Gates Product Application has been writing PA Notes - look at the major events of 1951 to place the time in context:

• The Korean War was underway
• The Twenty-second Amendment to the United States Constitution, limiting Presidents to two terms, is ratified
• The first live sporting event seen coast-to-coast in the United States, a college football game between Duke and the University of Pittsburgh, is televised on NBC
• Direct-dial coast-to-coast telephone service begins in the United States
• William Shockley invents the junction transistor

 Its a much different world that we live in, 59 years later.  The world has changed, as has the technology used in belt power transmission.  However, belts still remain one of the most useful, capable, and economical method of transmitting power between shafts.   Today's belts use highly engineered rubber and urethane compounds, a variety of belt tensile cord types, materials, and gages, and in some cases approach having so much power capacity that users can't believe how much power can be transmitted in such a narrow belt.  A far cry from 1951!

 

 

 

Gates Supports over 240 FIRST Robotics Teams

It's the middle of March, and the 2010 FIRST Robotics Competition is in full swing. Gates is a proud sponsor this year's competition, and has provided free customized belt and sprocket assemblies to over 240 teams. All senior FIRST Robotics students who have a robot that uses a belt drive system in a competition are eligible to apply for a $2000 Gates scholarship. More information can be found at www.gates.com/FIRST. The scholarship deadline is April 30, 2010. For information on local FIRST Robotics Competitions near you, please visit http://www.usfirst.org/.

Belt Tension

When installing a belt drive it's critical to apply the correct ammount of tension to the belt for the drive to function properly, but how do you know what tension to set the belt to? It turns out that there is not a universal tension for a belt, but proper belt tension will vary depending on the input power, rpm, and pulley sizes. Tension equations can used to calculate the proper static tension and can be found in Gates Drive Design Manuals. Using Gates free drive design software, DesignFlex or Design IQ, is another way to find out the proper tension for a belt drive. Both programs are available online at www.gates.com/drivedesign.

Belt Drive Design Programs

Design Flex Pro and Design IQ are two belt drive design programs offered from Gates that can simplify the process of designing an industrial belt drive.

Design Flex Pro is used for designing two-point belt drives ( 1 driveR shaft and 1 driveN shaft) and is easy as choosing a belt line, entering in your drive information, and hitting the Design button. DF Pro will then give a list of belt drives that will agree with the input conditions and summarize the information in a Drive Detail Report. This program can only design with stock products offered from Gates.

Design IQ is a more complex program where you can design a Belt Drive with multiple driveN shafts. You can also use idlers and tensioners when configuring the drive. Design IQ gives the user flexibility such as entering multiple driving conditions and implementing non-stock pulley sizes.

Both Design Flex Pro and Design IQ are free programs available to download from www.gates.com/drivedesign

Gates supporting FIRST Robotics

Over the past few years, Gates Corporation has been the proud sponsor of the FIRST Robotics Competition (FRC). The FRC is competition that challenges teams of high school students to create a robot in 6 weeks that can be programmed to interact with other robots to accomplish prescribed tasks against a field of competitors. This program is expected to involve over 45,000 students from over 1800 schools worldwide for the 2010 season. Gates has worked with the organization to help donate belt drive components to the teams as well as provide free engineering support and advice. Gates is truly proud of the work that these students do, and is happy to help support them in this event. To learn more about Gates involvement with FIRST, please visit www.gates.com/FIRST. To learn more about FIRST, please visit www.usfirst.org.

Aircraft Applications

One of the applications that you won't see Gates support is any primary flight related aircraft application.   Sometimes requests to the Gates Power Transmission Product Application department come from homebuilt aircraft builders or designers - they see the weight and performance advantages of a belt drive and would like to incorporate that technology into their aircraft.

Our answer is always "No".   To quote the official Gates policy regarding aircraft applications:

"Primary In-Flight Aircraft Systems:  Do not use Gates belts, pulleys or sprockets on aircraft, propeller or rotor drive systems  or in-flight accessory drives.  Gates belt drive systems are not intended for aircraft use."

Belt inspections will not be able to reveal how much useable life a belt may have left.  While properly designed belt drives are extremely reliable, considering the statistical distribution of belt failures, even a single failure can have catastrophic results in an airborne application.

So - don't use belts on an airborne application.  Don't ask Gates to provide technical assistance for airborne applications.  We'll be polite in discussing the topic with you, but the message will be as discussed above.