New Light Power & Precision Drive Design Manual

We are excited about the release of the newly updated Light Power & Precision Drive Design Manual dated January 2015.  This badly needed update includes drive selection data for newly released PowerGrip GT3 belts.  In addition, pulley dimensional tables and long length belting ratings were updated along with numerous additional items. 

The Light Power & Precision Drive Design Manual has always been focused on OEM designers needing detailed technical information about small pitch synchronous and Polyflex JB / Micro-V belt drive systems.  This manual contains extensive technical information useful for designing small belt drive systems including belt and sprocket/pulley dimensions and tolerances.  Many useful calculations are included for static belt tension, belt span tensions, center distance, teeth in mesh, arc of contact and much more.

Download a copy of this new manual from http://www.gates.com/drivedesign.  For additional information, contact Product Application Engineering at ptpasupport@gates.com or at 303-744-5800.

Micro-V Belts

Gates has a line of belts that we call Micro-V. They are called this because the belt is made up of a band of small V-belts put together. They are also called Poly-V belts by others in the industry. These belts are actually very common, in fact, you may have worked on one, and not even known it! Micro-V belts come in different sizes, or sections. One of these sections is called K-section, this is the type of belt that runs the accessory drives (alternator, water pump, etc…) under the hood of your car. While they are commonly called serpentine because of the way that they move around the pulleys, these are in fact K-section Micro-V belts. K-section belts are mainly used on automobiles and industrial gasoline and diesel motors. The less known sections of Micro-V’s include H, J, L, and M sections. H section is very small, and is typically not used for design except by large OE’s. J , L, and M section belts are the standard industrial line that we can help you design with. These belts push a lot of power for their size, are quiet, and can handle higher speeds well. One thing to keep in mind, however, is that we don’t have any off the shelf pulleys for them. This means that you would either need to have something made to order, or you could contact us for the groove information to create your own pulleys. You can find more information about these belts in our Light Power and Precision Drive Design Manual or as always by contacting us directly.

Water & Synchronous Belt Resistance

Light and occasional contact with water, such as occasional wash downs, should not generally affect synchronous belts seriously. Prolonged contact such as spray or submersion, however, can have detrimental effects.Rubber synchronous belts are considerably more vulnerable than Poly Chain GT Carbon belts.


With rubber synchronous belts, water soaking reduces the tensile strength of fiberglass tensile cords in addition to breaking down adhesion systems between the cord and the rubber compound. While aramid type tensile cords are more resistant to water than fiberglass, they are dimensionally unstable in the presence of water or humidity, so can result in belt length stability problems. Soaking also causes the rubber body to swell, lesser than but similar to oil contamination. This can negatively impact belt pitch fit with pulleys and sprockets in addition to material weakening. Additives to water such as lubricants, chlorine, anti-corrosives, etc. can intensify detrimental affects of water soaking.


Poly Chain GT Carbon belts are quite resistant to water soaking, and have even been used successfully in submerged applications. While urethane can exhibit a small amount of swelling, overall belt performance and the ability to transmit power remains relatively stable.


When considering the use of synchronous belt drive systems in moist or wet environments, the resistance of the hardware to corrosion is also very important. Coatings or treatments used on standard iron based hardware may not have adequate corrosion resistance. Special corrosion resistant coatings such as zinc or nickel plating are available on a made-to-order basis.


Contact our Made-To-Order Metals Group at (800) 709-6001 for further information about hardware corrosion protection options. Contact our Product Application Engineering Group at (303) 744-5800 for further information about applying belt drive systems in adverse environments.

Considerations for Synchronous Belt Drives on HVAC Applications

Some HVAC drives will experience high starting loads if the motor has an across the line start.  The fan will be forced to ramp up to speed nearly instantaneously, and the start up loads can be as much as 150% to 200% of the normal operating loads.

Designers that are considering using synchronous belts on HVAC drives need to be aware of this potentially high start up load.

If a soft start or variable frequency drive (VFD) is used on the drive, there is no need to take any special design precautions as the load is ramped up gradually.

If an across the line start up happens infrequently, simply applying a bit more installation tension will help prevent any ratcheting or start up issues.  

If start ups occur regularly and/or frequently, it is good practice to add .2 to the service factor when designing the synchronous belt drive.  This will provide a slightly more conservative drive design that will avoid any issues at start up. Learn more about HVAC drives and synchronous belts at Gates.com.

Gates Drive Design Manuals

Customers often ask where they can find technical information about Gates belt drives. The Gates Drive Design Manuals are a great resource for this type of information.

There are several manuals available at www.gates.com/drivedesign/:

• Poly Chain® GT® Carbon
• PowerGrip® GT2®
• Heavy Duty V-Belt
• HVAC
• Light Power and Precision
• Air-Cooled Heat Exchanger

Below is a sampling of the topics included in the manuals:

• Drive selection procedures (including power rating tables)
• Gates hardware specifications (for standard sheaves, sprockets, bushings, etc).
• Discussion of design considerations such as installation tension, conductivity, alignment, noise, flywheel effect, NEMA motors, tolerances, idlers, etc.
• Standard calculations
• General troubleshooting guidelines

Power and Fan Speed for Belt Drive Conversions

The power required to drive a fan relates to the fan shaft speed as follows:

Initial_Horsepower/New_Horsepower = (Initial_Fan_RPM/New_Fan_RPM)^3

A small speed change can result in a substantial increase in power consumption. Therefore, this relationship should be considered when replacing a V-belt drive with a synchronous belt drive for energy savings.

To ensure that the fan speed does not increase, the design speed ratio should be based on a measured fan shaft RPM of the existing V-belt drive. This measurement can be made with a contact or a strobe tachometer.

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.