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BDIExpress Knowledge Base

How to Identify a V-belt

Do you need to replace a worn out v-belt after years of running? Made of flexible rubber, the existing belt is likely stretched many different ways and might not even resemble a v-belt anymore! The following three (3) steps will help you to identify the right replacement, even if part numbers are no longer visible:

1.) The first step is to determine the cross section of the belt. This will ensure that it seats properly into the pulley sheave. Using a pair of calipers to get an accurate reading, measure across the top, widest point of the belt. Now refer to the image shown below to identify which cross section you have. Note that some cross-sections are very close in size. This is why it’s important to get an accurate measurement with calipers. It is also possible that the belt has worn it’s edges beyond the point of being able to correctly measure it. In this case, you will need a special gauge to measure the groove of the pulley and obtain the belt cross section (BDI can provide these gauges at no cost -- just email us or stop by our local service counter).

2.) Determining length is the next step. To do this, mark a starting point on the outside or topside of the belt. Using a flexible measuring tape, measure all the way around the outside, back to the starting point and take note of that measurement.

3.) Part number assessment is next. If you have determined that you have a 3V, 5V, or 8V, as an example -- take the length you measured, add the cross section in front of the length and add a 0 to the end. For example: 5V cross section + 65″ outside length + 0 = 5V650. Now you’ve got a good v-belt part number!

A,B,C,D, and E belts are slightly more complicated. Their part numbers actually signify the inside (and not the outside) perimeter. The inside perimeter is easily obtained by subtracting a predetermined factor for each cross section. Note the predetermined factor list below. 

  • A belt – 2″
  • B belt – 3″
  • C belt – 4″
  • D belt – 5″
  • E belt – 7″

So for a B section belt + 65″ outside – 3″ = B62.

If the belt has cogs or teeth cut or molded to the inside of the belt, add an X after the cross section designation. Examples: BX62 or 5VX650.

If you have multiple belts that have been banded (or sometimes called "ganged") into one belt, put the number of belts followed by a “/” in front of the number. A 3-band belt part number might look something like "3/B62" or "3/5VX650."

  • Type: How-to
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Comment By Rich Villegas - Sep 11, 2017 7:31 PM
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