V-belt selection tips that pay off.
Regardless of the type of materials handling application, if V-belts transmit the power, sooner or later you'll be replacing them. And that means an opportunity to upgrade the drive.
In typical applications such as on belt conveyor drives, a belt service life of three years can be expected in an around-the-clock operation. However, if the belt has been improperly selected or installed, its service life will be considerably shorter.
Proper selection and installation are the two crucial factors that govern the life-span of V-belt drives. If it's time to replace a drive's belts, then it's time to evaluate whether changing to different sizes or types of belts and sheaves will pay off in longer life and better performance.
First, do you select a classical industrial V-belt (A, B, C, D, or E belt) or an industrial narrow belt (3V, 5V, 8V)? Classical V-belts have been the industry standard for years; narrow V-belts are a newer product with a higher horsepower capacity. In general, a drive that uses the newer narrow V-belts will be lower in cost and will often permit the use of higher-speed, lower-cost electric motors. But because the sheaves are not interchangeable, converting a drive from classical V-belts to narrow belts will require new sheaves and belts.
Let's turn to design horsepower. Selection charts in manufacturers' drive design manuals are based on design horsepower. But the design HP is. rarely the actual HP to be transmitted. When selecting V-belts, factor in the effect of power surges or peaks during the machine's operating cycle.
Use standard sheave diameters unless there's an overwhelming reason to use a non-standard one. Standard sheaves cost far less, and are much more likely to be available from stock.
When calculating the number of belts required for a drive, the number that results is rarely an integer. Although rounding down may seem to cut costs initially, it's asking for a shorter drive service life. It makes more sense to round up instead.
Finally, don't brush over the correction factors for belt length and are of contact. The number of flex cycles that a given segment of a belt will be subjected to is related to belt length. The longer the belt, the fewer the flex cycles. If the arc of contact is less than 180 degrees, the V-belts will need to operate at a higher tension in order to transmit the required HP without slipping.
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|Title Annotation:||materials handling equipment|
|Publication:||Modern Materials Handling|
|Article Type:||Buyers Guide|
|Date:||Apr 1, 1995|
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