Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Tube sizing, Shaft dimensions, lobe dimensions, etc

Tube sizing, Shaft dimensions, lobe dimensions, etc

Tube sizing, Shaft dimensions, lobe dimensions, etc

So I'm new here and wanted to know how you go about knowing/calculating the dimensions of various parts of the automobile. I've gone through a lot of textbooks on the subject but they don't really go into detail of adequate size or dimensions of camshafts, crankshafts, etc. I haven't seen anything that can tell me about fluid flow either (tubing diameters of power steering, and brakes in particular). Spring stiffnesses for shocks, lengths of connecting rods, spacings of engine chambers, etc, etc. Gear design for differentials, transmissions, is also another topic.

Another thing that I'm curious about is the exact fluid mechanics of valve body designs on automatic transmissions. How the hell are they able to actuate gears with pressures and flow?

I don't know if anyone can tell me about any of this from their experiences or if there's some literature out there for any of this (I've tried looking for it but with no success). I've looked at the SAE site for standards but it'll cost me more than I can afford.

Until I know or have access to most of these things I mentioned I'm just aimlessly CADing crap in Solidworks, simulating stuff in ANSYS and that gets old when you have no range of measurement or any sensible practicality behind any of it.

RE: Tube sizing, Shaft dimensions, lobe dimensions, etc

Trouble is you've covered more in one post than I've learned in 40 years. I've never sized a brake hose, worked on a cylinder head design, and the internal designs of auto trans are a special black art (I know enough to be dangerous there). You are right, SAE standards don't really help that much, papers are the useful product. The exception is the SAE spring design manual, that is actually pretty good.


Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Tube sizing, Shaft dimensions, lobe dimensions, etc

As Greg said, you've covered a whole range of components - all of which start with the basics of engineering, then branch off into specifics as needed. Much of what you seek is covered by proprietary information - info that component manufacturers will not share because their competitors might find out things of value.

Your best bet is to read up books on the specific compinent you are interested in - and there are many.

RE: Tube sizing, Shaft dimensions, lobe dimensions, etc

Not many designs start from a clean sheet of paper. Either you've made several (million) widgets before or you buy the best widgets on the market and test them, tear them down and analyze the whee out of them then try to make a better widget. Very few engineers start at the top level vehicle design. Most of us work on some little niche widget on the vehicle toiling away in obscurity for the betterment of the entire beehive.


The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Tube sizing, Shaft dimensions, lobe dimensions, etc

To learn anything well takes time and effort. If you want to succeed in this industry expect 3-5 years minimum of intensive study on the job in a given niche before anyone considers you competent, much less an expert. If you divide a given vehicle into powertrain, chassis, and body systems, then figure there's a couple dozen niches within each its easy to see that one could spend multiple lifetimes in this industry learning.

One recommendation if you're considering this as a career - learn a proper engineering modeler (Solidworks doesn't count), preferably CATIA, Creo, and/or NX.

RE: Tube sizing, Shaft dimensions, lobe dimensions, etc

I doubt whether carmanufacturers do design all the components you mentioned. Most of them rely quite a bit on the components industry and only supply sufficient basic information to them to let them come up with suitable suggestions. Of course those suggestions are then extensively tested and based on the findings modified as needed, but in the majority of cases detailing is left to the component industry, as is the actual manufacturing.

RE: Tube sizing, Shaft dimensions, lobe dimensions, etc

I worked in the automotive field for a number of years. Some R&D and some system design. One person doesn’t do a car. One person may design door handles...period. There is a lot to a door handle. The art team give you what they want, you inturn give then what you can design mechanically, then manufacturing gives what they can make, then the all important “bean counters” get in the act and say the whole thing costs too much. Now everybody has to rethink the project. Save a nickel in the auto industry and you are a hero. I worked a lot in assemble machine design. We were a relatively small player but as many as 30 of us worked on just a basic body assembly line. Just managing the CAD system was several people who just did that. A mistake in thinking how the Cad models were to be restrained cost us a month in design time.

So as noted, finish school maybe get an advanced degree. Heavy in math and machine design. I’d highly recommend a year or more in the machine shop learning basic machine tools.

I once worked with a very well educated lady. We were discussing an R&D project we were teamed on. She said she could handle the math and chemistry if I could do the design mechanicals as she felt weak there. And we did. Our project ran as required right out of the box. And no we never dated or went out for drinks.LOL

RE: Tube sizing, Shaft dimensions, lobe dimensions, etc

Hmm, I think you are being overspecific, although to be fair I haven't worked for a monolith manufacturer.

That is, the door handle engineer would actually be working on at least door closing mechanisms in all their glory rather than just the bit that sticks out of the car. At one point on the Mercury Capri there were exactly two chassis design engineers. My mate Brent copped the tricky bits, I was just wheels, tires, suspension, steering gear and steering column. A bit leaner than we'd do it today!

You wouldn't believe how many problems this wheel caused


Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Research Report - How Engineers are Using Remote Access
Remote access enables engineers to work from anywhere provided they have an internet connection. We surveyed our audience of engineers, designers and product managers to learn how they use remote access within their organizations. We wanted to know which industries have adopted remote access, which software they are using, and what features matter most. Download Now
eBook - Managing the Context of Product Complexity Using the Digital Twin
Keeping track of changes to complex products is difficult—think Aerospace & Defense equipment, new generations of commercial aircraft, and software-based automobiles. A new way to managing the digital context of the physical product is required and the answer is the Digital Twin. This ebook explores the opportunity available for Operations and Maintenance for the Digital Twin. Download Now
White Paper - Trends in Industrial Filtration
Substantial progress has been made in filtration technologies in recent years. New filter media materials, designs and processes have led to filters that are more efficient, reliable, compact and longer lasting. This white paper will discuss the various trends that are impacting operational responsibilities of MROs today and the resources that are available for staying up-to-date on the latest filtration solutions. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close