Gearbox design 1

[havok91]

Anyone know of a good source on automotive gearbox design? I know I can use classical strengths, gear and bearing design equations to design everything around. However, I would like to glean any usefull info I can to make the design flow much easier. So, any ideas?

Mike

 

[Bribyk]

I think the toughest part would be selecting a design life and estimating/determining the loads. Shaft, bearing, clutch and gear design is pretty straightforward and most of the formulas have been around for over a century, if not longer. Oiling and FEA on the case would probably be the toughest design. I've never done it but that's my $.02.

 

[havok91]

"Oiling and FEA on the case would probably be the toughest design"

Exactly, that is why I'm hoping for some good material to read. I'm actually looking at retrofitting a transmission with dog faced gears for road racing.

 

[MikeHalloran]

I could swear that most manual transmissions already have dog clutches.



Mike Halloran
Pembroke Pines, FL, USA

 

[patprimmer]

Yes mike but the little cone shaped clutches confuse some people, and mostly the dogs are quite numerous and small. Some only notice when there are three big ones.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers for professional engineers

 

[havok91]

Yes, there are dog teeth on the synchro pack. However, I'm talking about getting rid of the conical synchronizers and using castelated teeth standing perpendicular to the face of the gear for engagement.

Kinkd of Like this:

http://www.swiftune.com/Product/411/swift-shift-dog-engagement-kit.aspx

 

[patprimmer]

The straight up dog engagment should have no influence on the case and the straight cut gears as shown will all but eliminate end thrust, thus reducing the load on the case. I don't see a problem unless you already have a case durability problem or intend increasing engine peak torque.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers for professional engineers

 

[havok91]

The gearbox in question is for a 3000GT/Stealth TT. Torque, of course, will be increased. I suspect, however, the increase in shock loading will place higher loads throughout the entire load path.

Nevertheless, the question remains: Any text available?

 

[dicer]

Fine dogs, otherwise known as shift splines?

I thought you said it already had the dog faced gears and were converting to the spline, when I first read this.
I have seen the face dog type and think it is much easier for that design to wear and create axial thrust and slip out of gear easy. If that was a great design then outfits like Dana /Roadranger would be using it in heavy duty truck transmissions. What is needed is a good study of some good existing manual transmissions for some ideas.

 

[gearcutter]

"High Performance Gear Design" by Alec Stokes.
ISBN: 0212853336.
It's a book from around 1970 but the writer has alot of experience with Formula 1 and other high performance automotive gearboxes.
It is old but has alot of truths and principles still apropriate today.

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[havok91]

"High Performance Gear Design" by Alec Stokes

Thank you,


Mike

 

[tbuelna]

havok91,

You did not really specify what this gearbox will be used for. The end use requirements will make a huge difference in how you design and analyze the gearbox, and also in what reference material you use in your work.

If it's a racing gearbox with limited life requirements, low weight requirements, no need for high production rates and little concern with cost, then you will design the gearbox in one manner. I don't know of any good texts covering race gearbox design. Your best bet would be to get friendly with someone that works at a company like Xtrac, Weissman, Hewland or Quaife, and pick their brains.

If it's an on-road gearbox, needing quiet operation, smooth shifting, long life, high reliability and low cost, then you would design the gearbox another way. The hardest gearbox to design, by far, is the production automotive gearbox. Designing gears, bearings, shafts and synchro rings that are durable, low cost, easy to assemble and totally reliable is incredibly difficult. The best resource for production automotive gearbox texts is the SAE. But they're not cheap.

Good luck.

 

[EngJW]

SAE published or sold a book on gearbox design a few years ago. I'm out of town so I can't get the name, and don't know if it is still in print. It was not a very good book, but better than nothing. (actually it might be by the same Stokes mentioned above, but different title)