How to Measure V Belt Tension

by Andrew Copley
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Checking the tension of all your V-belts is important. Too much tension, and the belt will stretch and start to tear. Not enough tension causes the belt to slip and the pulleys scratch away at the belt. For each device, be it a car or washing machine, there is a specific amount of pressure the belt needs to be under in order for it to work efficiently.

There are two measurements used in belt tension. Length of belt and amount of pressure for deflection. Knowing these measurements helps you setup and use your tension gauge.

Step 1

Make sure the unit is turned off and the pulleys you are working with are not moving.

Step 2

Do a visual check of the V-belt to see if it is cracked or worn in any spots. Look for any shiny parts along the part of the belt that comes in contact with the pulleys. This indicates belt slippage. A damaged or excessively worn belt needs to be replaced.

Step 3

Measure the distance from the center of one pulley to the center of the second pulley. If there are more than two pulleys on the belt, take your measurement using the two pulleys with the longest span of the belt.

Step 4

Multiply that measurement by one-sixty-fourth of an inch. If your belt is 16 inches, the equation is 1/64 x 16 = 16/64 or 1/4 of an inch. Set the "O" ring on the handle of your tension gauge to the measurement from your calculation. Set the second "O" ring on the plunger against the body of the tension gauge at the zero mark.

Step 5

Place your piece of wood against the two pulleys, and line it up with the top edge of the pulley you are testing. Hold the wood in that position without moving it. Place the plunger end of the tension gauge on the top of the belt. Holding the tension gauge vertical to the belt press down until the bottom of the "O" ring on the plunger is even with the top of the wood.

Step 6

Lift the plunger from the belt, and read the pounds of force measurement at the "O" ring on the plunger. This is the measurement that should match with the specifications listed in the manual for the device.

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