BESTORQ X3 A37 or 4L390 Belt 12"x12"x1/2"

BESTORQ A37 classical V-belt, A section, also designated 4L390. The belt is marked BESTORQ X3, STATIC CONDUCTING, OIL & HEAT RESISTANT.

In the RMA classical system an A-section belt carries a 1/2 in (0.50 in) top width and 11/32 in nominal thickness, and the number states the INSIDE circumference in inches: A37 measures 37 in inside, 39 in outside. The fractional-horsepower 4L designation states OUTSIDE circumference in tenths of an inch, so 4L390 is 39.0 in outside. Both numbers describe this same belt at the same length, which is why both are printed on it: A section is rated for industrial duty, 4L for lighter fractional-horsepower drives, and either runs in the same sheave groove.

Classical V-belts drive the everyday rotating equipment of industry: HVAC blowers and exhaust fans, pump drives, air compressors, and shop machinery. Belts are wear consumables, so cribs stock exact lengths and a cracked or glazed belt becomes a five-minute swap rather than a down machine.

1. New in Box. 11 available; price is per belt.

New surplus, available from King Surplus inventory in Del Rio, Texas.

• Manufacturer: BESTORQ
• Product Line: X3
• Industrial Designation: A37
• FHP Designation: 4L390
• Section: A / 4L
• Top Width: 1/2 in (0.50 in)
• Nominal Thickness: 11/32 in
• Inside Circumference: 37 in
• Outside Circumference: 39 in (39.0 in per the 4L designation - the two agree)
• Marking read on the belt: A37 or 4L390
• Belt Properties (as marked): STATIC CONDUCTING, OIL & HEAT RESISTANT
• Dimensions (packaged): 12.0x12.0x1.0 in
• Weight: 4.0 oz
• Spec Basis: RMA classical and fractional-horsepower V-belt section standards as published by Bestorq distributors (usbearingsandbelts.com, mrosupply.com) and the HVH Industrial / Texas Belting conversion references, reconciled against the markings visible on this belt.