What are the designations for fractional horsepower V-belts?

The designations for fractional horsepower V-belts are indeed identified as 3L, 4L, and 5L. These designations reflect the width and height of the belts in a manner that is specific to fractional horsepower applications.

For example, the numeric part of the designation corresponds to the belt's nominal width in eighths of an inch, with 3L measuring 3/8 inch wide. This standardization helps in ensuring compatibility with specific pulley systems designed for fractional horsepower motors, which typically operate at lower power levels than other belt systems.

The other designations provided, such as A, B, and C, refer to different types of V-belts that are used primarily for standard power applications, not specifically for fractional horsepower. The designations F, H, and P typically correspond to other classifications or standards that may not pertain directly to fractional horsepower, while 1L, 2L, and 3L do not correctly represent the recognized classification in this context.