Strength & size checks for small Bevel Gears

[EMS21]

I've been using the Mechsoft Bevel Gear wizard (a Solidworks 2004 add-on) to do design plus strength checks etc for a small 3:1 10DP Bevel Gear Transmission for a small Helicopter (2 Stroke engine 2 cyl 24Hp @5000 rpm) so after finaly settling on dimensions that give the green light the Gear has an approximate Gear size of around 4.5" ... ok not so bad ! but I would like this to be as small as possible due to weight factor.

2 days ago I visited a local Marine shop and on the counter top was a bunch of Spiral Bevel gears from various makes and models of outboards ... one of the gears I picked up was approx 3" and from a 40 Hp Suzuki, these do have a reasonably generous face width of around 3/4" to 1' or so.
Is mechsoft over doing the strength check ?
I need reliability but not the beef factor and I'm curious as something seems off here ?

looking at several Co's who make gears there also seems to be a wide gap in strengths due to material's and Hardness etc when trying to compare products with similar load and speeds.
I'm curious as to what others out there would consider a suitable DP or Module for a 3:1 Gear set with 24Hp at 5000 Rpm ?


TIA
Thomas

 

[TVP]

Thomas,

If you do not know the stresses (bending and contact) on the gear, then it is difficult to know how conservative the Mechsoft wizard is. Is your design also a spiral bevel gear? Do you know what material, hardness, and case depth are being considered by the Mechsoft wizard?

 

[paulliu]

Bevel gear design is a serious mechanical engineering
subject. A acceptable approach is to follow the following
standard:

"ANSI/AGMA 2003-B97 - Rating the pitting resistance and
bending strength of generated straight bevel, zerol
bevel and spiral bevel gear teeth"

AGMA has been creating a design software based on
the above document. If you have a further interest,
contact them:

http://www.agma.org

and ask
when it'll be sold.

Good luck!