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ISC Companies and affiliate Adams-ISC are distributors of mechanical power transmission parts including v-belts. For more information about the brands we offer and/or pricing, please contact us by phone 763-559-0033, by email [email protected], or by filling out our online contact form.

V-Belts are the most common type of drive belt used for power transmission. Their primary function is to transmit power from a primary source, like a motor, to a secondary driven unit. They provide the best combination of traction, speed transfer, load distribution, and extended service life. Most are endless and their cross section is trapezoidal or “V” shaped. The “V” shape of the belt tracks in a similarly shaped groove on a pulley or sheave. The v-belt wedges into the groove as the load increases creating power distribution and torque. V-belts are commonly made of rubber or polymer or there may be fibers embedded for added strength and reinforcement.

V-belts are generally found in two construction categories: envelope (wrapped) and raw edge.

  • Envelope: also known as wrapped or jacketed, has a fabric cover and is molded into a “V” shape. Wrapped belts have a higher resistance to oils and extreme temperatures. They can be used as friction clutches during start up.
  • Raw Edge: does not have a cover. It is cured and then cut into a “V” shape. Raw edge type v-belts are more efficient, generate less heat, allow for smaller pulley diameters, increase power ratings, and provide longer life.

V-belts may be cogged or non-cogged. Cogs allow more flexibility when used with small diameter pulleys or back-bending idler pulleys. Cog configurations can be evenly-spaced, randomly-spaced, perpendicular, or angled.

Classic V-Belt Designs

  • Fractional Horsepower (FHP), Light Duty: FHP belts are used singly on drives of less than 1 HP and are identified with a 2L, 3L, 4L, or 5L prefix. Never replace a standard duty belt with an FHP belt, as it cannot handle higher horsepower.
  • Classic A, B, C, D, E (Standard Duty): ISO designations of W, Y, Z, A, B, C, D, and E (W, Y, Z are rarely used in North America). The part number format is the cross section size followed by the inside length in inches. Classic v-belts cover a load range from fractional (less than 1 HP) to 500 HP.
  • Kevlar V-Belts: Used with drives that require reverse bending or clutching.
  • Classic Banded A, B, C, D: Speed fluctuations can cause single v-belts to turn over in the sheave. Banded belts prevent this by using a backing material across several single belts that work in unison. A prefix in the part number identifies the number of belts in the band (4/5VX1200 is a four belt banded set).
  • Classic Cogged AX, BX, CX: A flat belt with a corrugated driving surface (ridges run longitudinally around the inside surface). They work well with small diameter sheaves and can tolerate reverse bending, high linear speed, and high speed ratios. But, tensions run higher and there is a greater tendency for the belt to jump ribs in misaligned conditions.
  • Classic Cogged Banded BX, CX
  • Classic Wedge 3V, 5V, 8V: Narrow, or wedge, design provides more support to the center of the belt, has greater contact surface with a sheave, and allows for higher horsepower with a narrower footprint and reduced overhung bearing load.
  • Classic Wedge Banded 3V, 5V, 8V
  • Classic Cogged Wedge 3VX, 5VX
  • Classic Cogged Wedge Banded 3VX, 5VX
  • Classic Double AA, BB, CC: Double-sided v-belts are used in applications where the belt has the ability to reverse bend.
  • Multi-Speed (Variable Speed): A special class of a two-sheave drive that can vary the driven sheave speed. Sheave width is adjusted manually or by automatic sensing. As sheave width changes, the belt rides deeper or shallower in the sheave, allowing for infinite speed ratios within adjustment range. Either the driving or the driven sheave, or both, can be the variable pitch sheave. The majority of variable speed belts are custom sizes.
  • Micro Rib (Serpentine): Extremely flexible and will function well on pulley with small diameters and serpentine drives.

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PTDA-Handbook-CoverContent on this page was created using excerpts from the Power Transmission Handbook (5th Edition), which is written and sold by the Power Transmission Distributor’s Association (PTDA).

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ISC Companies and affiliate Adams-ISC are industrial distributors of bearings and mechanical power transmission parts. We have many different models and brands in stock for fast delivery. Our sales professionals are happy to assist you in the selection process to ensure the correct part is specified for your application. Get a quote by clicking below on “Request Pricing” and filling out the contact form or give us a call at 1-800-627-9434.

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