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?

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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.