Overhung Load for Roots Positive Displacement Blowers

Proper V-Drive selection is essential to achieve maximum life for your blower and vacuum pump. Improper sizing or installation of a v-belt drive can shorten the life of the blower or even cause failure. Roots has provided a means to calculate the overhung load on the drive bearing and provide operational limits to these loads.

Use the following equations and table to verify that the v-belt drive on your blower does not exceed operating limitations.
Overhung Load Sketch

Calculate the belt pull for Roots Universal RAI with the following equation:

URAI Belt Pull Calculation

Calculate the Shaft Load with the following equation:

Shaft Load

URAI Frame Dimension “A” Max Allowable Shaft Load (lb.-in.)
22,24 0.61 150
32,33,36 0.8 400
42,45,47 1.02 650
53,56,59 1.13 1325
65,68,615 1.36 2250
76,711,718 1.16 2300


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