Yellow Bullet Forums banner

1 - 3 of 3 Posts

·
Registered
Joined
·
8,147 Posts
Discussion Starter #1
I understand why most gear teeth have an involute profile, but why do splines need that? Can I put MWE involute spline axles into my GM/Eaton posi?
 

·
Moderator
Joined
·
140 Posts
Yes you can.

Axle spline has the same involuted profile as spur gear tooth. The difference is they have a shallower depth. Common automotive splines have combination pitch to depth ratio . A common specification is 24/48 whitch means in a 1.00” pitch diameter shaft there are 24 teeth. The Center to center distance of each tooth is .1309” (3.1416/24). The depth on the spline is signified by the /48 that will calculate to (3.1416/48) or .0645 deep. I realize this is way more information than you asked for but that’s how real automotive splines work.

The short answer is if you make a male spline with straight side teeth it has contact one spot against the curved involuted female spline. This create a higher stress load rather than distributing load even across the spline face. Properly engineered axle shafts have curved involute splines. Axles made with straight splines are just taking the cheap and dirty way out.
 

·
Registered
Joined
·
8,147 Posts
Discussion Starter #3
More info than I asked for is always welcome (in a tech forum, anyway)!

With spur gears, you have teeth meshing and unmeshing, or maybe it's engaging and disengaging, but whatever the terminology is it looks like this:


With splines, there is constant engagement, right? Is it the clearance between the male and female splines that makes involute geometry desirable?

What would be the most extreme example of the opposite of involute splines? An equilateral triangle cross section?

I don't mean to barrage you with stupid questions, but I'm trying to understand in spite of having no formal training in engineering.
 
1 - 3 of 3 Posts
Top