Quote from tristancliffe :

Aren't all gearbox gears involute teeth, so there isn't any 'clashing', as each tooth rolls on the next one, reducing wear and peak loads...

then why would they make all that noise ?

Dunno. But I plan to find out. Time for...

Research!


Tomorrow. Or Sunday. Or when I get round to it. Anyone else want to be my research understudy (i.e. do it if I forget)?

Quote from Shotglass :

then why would they make all that noise ?

Sounds waves take energy to create, therefore an "impact" must be taking place & there's no way around that. So, Spur gears must be taking a beating in that particular regard. I really doubt that this means they will fail any noticable amount sooner though, since it's probably so miniscule compared to the 100s of lb ft of torque being put through the gear.... I can make noise by clashing two items but that takes considerably less force to do than it would to accelerate a car!

I would think that the only real disadvantage to helical gears are the mentioned losses due to thrust, and the cost. As far as the gears themselves... There's no reason I can think of to suppose that one type is inherantly stonger than the other. Given the same tooth size, shape (save for the "cut pattern" obviously), materials and whatnot; why would they be different? They just impose effects on the componts of the transmission they are mounted in (bearings, shafts) differently.

Quote from Gentlefoot :

The reason is that helical cut gears are pushing away from each other and this creates the loses. Straight cut gears are not pushing away from each other so all the force is transferred from one cog to the next.

All gears want to push "away" from each other, because they are exerting a force against each other and the teeth are angled with relation to each other EXCEPT for a breif instant where the force is totally perpendicular to the contact point of said teeth. There is still insane loads on the bearings of the shafts of a racing gearbox with spur gears, it's just that effectively none of the load is a thrust on the shaft, but rather pushing the shafts apart.

I would hazard a guess that it's "only" because spur gears are cheaper and more efficient that they are used in racing boxes.

Quote from Ball Bearing Turbo :

Sounds waves take energy to create, therefore an "impact" must be taking place & there's no way around that.

thats what i suppose as well

Quote :

So, Spur gears must be taking a beating in that particular regard. There's no reason I can think of to suppose that one type is inherantly stonger than the other. Given the same tooth size, shape, materials and whatnot; why would they be different?

the teeth themself probably dont have much of any difference in durability
the constant beating they get should however make them more prone to failure and deformation than helical cuts

Quote :

All gears want to push "away" from each other, because they are exerting a force against each other and the teeth are angled.

he meant that with straight cut gears there are no additional axial forces to the angular forces

Quote :

I would hazard a guess that it's "only" because spur gears are cheaper and more efficient that they are used in racing boxes.

and if im correct also that racing gearboxes arent run half as long as steer boxes
plus the obvious bit that a racing driver wont give a damn how loud his gearbox is

Yikes, I didn't even have time to update my post! You're always fast as lightning on here no matter what time of day....

Quote from Ball Bearing Turbo :

Yikes, I didn't even have time to update my post! You're always fast as lightning on here no matter what time of day....

No sweat, you can take him on the tracks

Quote from Shotglass :

then why would they make all that noise ?

Because the temperature of the gears is variable and therefore the size is as well, you better design the thing with some lash or else you might have something unpretty happen when it all gets hot. So involute profile and all, they still make plenty of noise.

Quote from BBT :

I would hazard a guess that it's "only" because spur gears are cheaper and more efficient that they are used in racing boxes.

Consider how much lighter a gearbox can be made when it doesn't have large axial loads on the shafts.

:

Haven't seen you around for a bit; good to see you post