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.