Help with gear math

[alazo1]

Say you have 3 gears.

Driving gear is 4"
an intermidiate gear is 1"
the next gear is 1"

Does the intermidiate gear have any play on the ratio of the third gear?.
Trying to come up with a 4 to 1 ratio but need an intermidiate gear.

Albert

 

[Lee Stockwell]

When calculating gears usually the tooth count is used instead of the diameter. Same difference however.

The 4" driving gear will cause the 1" driven gear to turn 4 times as fast. The second 1" gear will simply reverse the direction again.

Thanks,
Lee

 

[dgardner]

Gear ratios are usually calculated by counting the number of teeth on each gear, like 40 tooth/ 10 tooth = 1:4

Assuming that's what you mean, your first and second gears will have a ratio of 1:4, not 4:1, so the intermediate gear will turn 4 times faster than the input shaft.

The intermediate and final gears have a 1:1 ratio, so the output shaft will turn at the same speed as the intermediate gear, for a total ratio of 1:4.

 

[dgardner]

I gotta learn to type faster... What Lee said.

 

[alazo1]

Wow, thanks. Gotta go back to the drawing board though.

The second 1" gear will simply reverse the direction again

Forgot about this. Trying to come up with a planetary with gears and pulleys. Need last gear / pulley to have reverse from driving gear.

Albert

 

[Bill G. Martin]

That Lee is one smart Dude

Bill in central Florida

 

[Lee Stockwell]

Even number of gears needed. A problem with small gears is load per tooth, similar to the slippage problem with too small diameter belt pulleys. (A common design flaw in truckmounts).

We're happy to help. Describe your project please?

Thanks,
Lee

 

[alazo1]

Thanks Lee,
It's an attachment for a 175rpm buffer that has 3 4" heads similiar to a cimex or other stone machines. Though I intend to use for stone restoration, it can also be used for encapping. Thinking about 16 inch total.

This pic is for one that's about 1000 rpm. Looking for something about 1-4 or 5. No idea what the best tooth angle and number of teeth would be. The middle gear can be some kind of plastic otherwise it may bog a regular 1 1/2 hp machine. I figure I can just screw the regular adapter to the gear with a plate and shaft in the middle. For this one maybe a 10" gear in the middle and 3 2".

Here's one that I have in the 20" version. Sorry the pic is in the pdf file on the second p;age. Basically it has a fixed triple pulley in the middle with 3 belts.

http://www.onfloor.com/PDF/OF16INSERT.pdf

thanks,
Albert