Changing blower/pulley speed 1

[yzracer]

I need help finding the formula and using the formula correctly to change speed on a electric motor / v-belt driven blower. The blower pulley is a 3v3.65 3sh turning 3400rpm and the motor pulley is a 3v6.9 3sds turning 1750 rpm.
I need the blower to be turning 2750 rpm. How do I figure this out? I am not an engineer and any help would be appreciated.

 

[diskullman]

Basically, you must slow down your blower by 23.6%, or reduce the driver pulley by 23.6%, or use a 3V5.3 pulley on the motor. You have not mentioned motor horsepower or service factor or center distance, which come into consideration when specifying a belt drive. You can download software that will allow you to make the most logical & economical drive design at

http://www.gates.com

but you must register first

Russell Giuliano

 

[yzracer]

Thanks, for the reply. While I was waiting for a reply I found an old Machine Shop Mathmatics book and found the formula speed of drive x Dia. of drive
------------------------------ = RPM
Dia. of driven

I just kept changing the Dia. of driven until the RPM = 2400.

1750 x 6.9
---------- = 2415rpm
5.0
Does this look right?

 

[diskullman]

Basically yes. 6.9 divided by 5 will give you a 1.38 ratio or speed multiplier (without any correction factors for effeciency). 1.38 x 1750 = 2415

Russell Giuliano