gear ratio help please

[gochenour799]

I need help calculating a reducing gear ratio. Example.. I have a gasoline motor I want to run @ 2000 rpms and a pump that needs to be run a 1250 rpms so I need to reduce the out put by putting a small gear on the motor and a larger gear on the pump , with chain in-between them . I can't figure out how to figure the size of the gears . Say 10 teeth and 20 would that be 50% reduction ?

 

[allenr]

I need help calculating a reducing gear ratio. Example.. I have a gasoline motor I want to run @ 2000 rpms and a pump that needs to be run a 1250 rpms so I need to reduce the out put by putting a small gear on the motor and a larger gear on the pump , with chain in-between them . I can't figure out how to figure the size of the gears . Say 10 teeth and 20 would that be 50% reduction ?

2000 divide by 16 times by 10 = 1250.

So you'd need sprockets of 10 and 16 teeth for the motor and pump respectively.

 

[gochenour799]

2000 divide by 16 times by 10 = 1250.

So you'd need sprockets of 10 and 16 teeth for the motor and pump respectively.

Wow that was fast ..... THANK YOU so much for the reply..

 

[SpudHauler]

1250 divide by 2000 = .625

10 divide by .625 = 16

 

[Baby Grand]

A 10 tooth pinion is kinda racy. Try a 20 tooth pinion & 32 tooth gear.

 

[LD1]

or a 15 and 24

 

[spurlocktool]

Don't know if you've shopped for sprockets yet, but here are two places I've used that have good prices:

www.thebigbearingstore.com, click on "roller chain" to get to the sprockets link. They also have lots of inexpensive bearings.

BMI Karts and Supplies - Home, basically go-kart stuff but they have lots of big sprockets.

 

[gochenour799]

Ok thanks everybody... I think I will idle the motor down to 1950 rpms and run a 25 / 16 that will give me 1248 rpms on the pump .

.1950/25x16=1248 ... the reason is I already have these sprockets...and if I need more I can just bump the idle up on the motor .