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.


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




Calculate the Shaft Load with the following equation:

URAI Frame	Dimension "A"	Max Allowable Shaft Load (lb.-in.)
22,24	0.61	80
32,33,36	0.80	300
42,45,47	1.02	640
53,56,59	1.13	1100
65,68,615	1.36	1550
76,711,718	1.16	2300

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