V-Belt Installation

V-Belt Installation

V-belts run longer and perform better if they are given the proper care and attention during installation, and in particular while following 48-hour running-in period. Failure to observe these installations could result in bodily injury.

Proper installation techniques will assure that you get full service life and minimum downtime from your belt drives

1. Turn machine off and look out power source.

2. Remove belt cover, loosen motor mounts, and shorten center distance between sheaves. Remove old belts.

3. Inspect, repair, or replace drive components.


Clean oil, grease, and debris from sheaves; remove rust with a wire brush

  • Inspect and replace damaged sheaves.

Get your money's worth from a new set of belts by checking and replacing worn or damaged sheaves. In the long run replacement sheave cost will more than be recovered in increased belt life, reduced downtime, and lower maintenance expense.

Check the following:

a) Worn groove sidewalls, "Dishing" should not exceed 1/32" for individual belts. With a Combo belt, dishing should not exceed 1/64". When a Combo belt rides too low in belts in worn sheave grooves, the band can be cut by the flanges between the grooves.


Figure:1 Dishing & Worn Groove Sidewalls



b) Shiny sheave groove bottoms. This is a sure sign that the belt has bottomed out. The resulting slippage shortens belt life.

c) Wobbling and/or damaged sheaves. Generally caused by improper sheave or bushing installation, wobbling and/or damaged sheaves can unbalance a drive, wear out belts rapidly, and damage bearings.

  • Check and repair worn bearings and bent shafts.

4. Select replacement belts.

  • Replace all belts on a drive with a new matched set from one manufacturer.

a) Do not mix old and new belts on a drive. A new belt will ride higher in the sheave groove and operate at a higher tension than an old belt. Running them together will damage the new belt so it cannot carry its share of the load.

b) Do not mix belts from different manufacturers. Because dimensions and constructions will vary, running such "mismatched" belts will not give full service life.

c) Replace with correct type and cross section belt. Match "A" section belts with "A" sheave grooves, "B" to "B" etc. Do not use "B" section belts in "5V" sheaves, or vice versa, Never replace "A" or "B", belts with "4L" or "5L" fractional horsepower belts. Remember that dimensionally similar belts can have very different horsepower ratings.


5. Install new belts.

  • Loosen the drive take up and place the new belts on the sheaves. Press the belts with your hand to position the slack of each belt on the same side of the drive. If the slack is on different sides, start up loads can break belt tensile cords.
  • Do not try or force belts on the sheave. This can break the load carrying tensile "muscle" of the belt, and the belts will break or turn over shortly after installation.
  • Take up slack until the belts fit snugly.


6. Check sheave alignment.

  • Place a straightedge or taut string across sheave faces to correct misalignment.
  • Check parallel position of shafts and correct alignment of grooves.

NOTE: Mount sheaves as close to bearings as possible.


 7. Tension belts. (See note below)

  • Ideal tension for a V-belt drive is the lowest tension at which a belt will not slip under peak load.
  • Tension belts, replace belt guard, run the drive for 15 minutes, and apply full load. Retighten slipping or squealing belts.
  • Retention after 24 to 48 hours, when belts will be completely seated in grooves.
  • Do not use belt dressing. If the belt slips, tighten and/or check for worn sheave grooves.

NOTE: Store belts in a cool, dry place out of direct sunlight.


Figure: 2.1 Type of sheave and shaft misalignment (Horizontal)


Type of sheave and shaft misalignment


Figure: 2.2 Type of sheave and shaft misalignment (Vertical)


Type of sheave and shaft misalignment



Figure: 2.3 Type of sheave and shaft misalignment (Parallel)


Type of sheave and shaft misalignment