Minimum Belt Wrap and Tooth Engagement

Synchronous belt horsepower ratings listed in our catalogs are based on a minimum of six teeth in mesh between the belt and the sprocket. The ratings must be corrected for excessive tooth loading if there are less than six teeth in mesh. The number of teeth in mesh can either be calculated using Design IQ or the simple formula below

Where:                   D = pitch diameter, large sprocket, inches

d = pitch diameter, small sprocket, inches

C = center distance between shafts, inches

Ng = number of grooves in small sprocket

In cases where fewer than six teeth are in full contact, 20% of the horsepower rating must be subtracted for each tooth less than six not in full contact.
In addition to the number of teeth in mesh, some drives with more than two shafts may have a greater potential for the belts to ratchet where loaded sprockets have six teeth in mesh, but a small arc of contact. In order to minimize this condition, each loaded sprocket in the drive system should have an arc of contact, or belt wrap angle, of at least 60 degrees. Non-loaded idler sprockets do not have tooth meshing or wrap angle requirements.

8M / 14M PowerGrip GT2 Belts Are Now Static Conductive

PowerGrip GT2 belts in 8mm and 14mm pitches are now being manufactured in a static conductive construction that meets the ISO 9563 international standard for belt conductivity.  Belt labels now include "Antistatic To ISO 9563".  This will allow 8M and 14M PowerGrip GT2 belts to dissipate static electric charges into sprockets, and hopefully safely to ground.  This is important for belt drive applications operating in hazardous applications where sparks can ignite flammable substances as well as for belts used in equipment that must meet European ATEX requirements.

Using conductive belts is important when belt drives are operating in hazardous environments.  It is equally important, though, for there to be a conductive path from the sprockets to ground in order for static charges to be safely dissipated.  Motor and equipment mountings, shaft mountings, bearings, etc. can all influence the overall conductivity of the path to ground.  For this reason, secondary measures such as grounding straps or cables and grounding brushes are recommended to ensure safe dissipation of static electric charges.

What is Belt Pull?

Belt pull estimates the force a belt exerts on a shaft. It is the force applied to a shaft by the two belt spans entering and exiting a pulley.  Belt pull does not account for pulley weight or pulley location on a shaft.  While related, bell pull should not be considered to be interchangeable with bearing load or over hung load values. 

Belt pull values can be calculated using Gates Design Flex® and Design IQ® software programs, or by using formulas found in the Gates drive design manuals.

Gates PT Toolkit App for your smartphone!

Gates has recently come out with the mobile PT Toolkit App for your iPhone and Droid! With the mobile app you will be able to:

• Calculate energy savings                                                   
• Calculate belt drive center distance
• Calculate recommended belt tension
• Convert unit measurements

   

The PT Toolkit App is available for FREE at the market place for Droid's and at App Store for iPhone's. The app is not supported on Blackberries at this time.

Watch a tutorial on the PT Toolkit on YouTube: 

• Android: http://www.youtube.com/watch?v=Qj4lKD6D48A
•  iPhone: http://www.youtube.com/watch?v=wWND7qnnTr8

New Gates Carbon Drive Belt and Sprocket Calculator

If you have been following Gates Carbon Drive at all, you may be aware of the CDX Center Track system for bicycles. This system has changed bicycle belts completely. But beyond the simple performance and size benefits of the system, we are also offering an larger sprocket product line than we have in the past. Because Carbon Drive is 11mm specific, none of our other design programs will help you design for the proper ratio and center distance, including our online calculators at www.gatescarbondrive.com That is until now. We have a new online spreadsheet loaded up that has all of the new Gates Carbon Drive sprockets loaded into it. Check it out at: http://www.gatescarbondrive.com/installation.php?lang=us To get to the calculator, click on the link for Belt and Sprocket Size Calculator listed on the lower right hand side of the screen. Happy riding!

Preventing Potential Pitfalls in TaperLock Bushing Installations

TaperLock bushings have been in use in the Power Transmission Industry for over 30 years. With proper application and installation, they are highly reliable components. Based on questions that we receive, though, users should be aware of a couple of preventable pitfalls with their installation.

TaperLock bushings are sometimes accused of loosening after installation. TaperLock bushings need a little help beyond bolt tightening in order to grip hubs and shafts tightly. After the recommended bolt torque has been reached, the bushing faces should be tapped several times with a drift or punch in a circular pattern (don’t hammer bushing faces directly). This seats bushings more deeply into the tapered pulley or sheave hubs, increasing the gripping force. The bolts now need to be re-torqued to the recommended torque level as they will have loosened some. This process ensures that bushings are completely and tightly seated so will not loosen with usage over time.

Shaft keys are sometimes not held securely between shaft and bushing key seats and work out over time. They sometimes literally fall out in vertical shaft applications. This is due to manufacturing tolerance accumulations with shafts, bushings and keys so is only occasional. There are a couple of viable solutions. One is to apply a Loctite type adhesive to keys and key seats during assembly. Another is to punch keys several times on each side with a sharp center punch to raise the key surface slightly around the depressions. This will increase the total key thickness slightly enabling compression between shafts and bushings.

To learn more, watch our video on Taper-Lock Bushing Installation.

Check Out Gates Engineers on YouTube

In addition to blogging, our engineering group also creates short technical videos. The videos provide Gates customers a quick and simple means to learn about common topics. Some of the current videos topics available include:

• Belt Handling
• Belt Identification
• Bushing Installation
• Checking Wear with V-Belt Sheave Gauges
• Measuring Tension with the Sonic Tension Meter or Force Deflection Gauges
• Strobe Tachometer Use
• The Affinity Laws for Pump and Fan Applications
• Using the Design Flex Pro Belt Drive Design Software
• Using the Online Catalog (PartView)

Check out the videos at: http://www.youtube.com/user/GatesPT