For those familiar with spring design, A.M. Wahl’s Mechanical Springs” is still considered to be the consummate resource for the design of springs. The text is a rather complete mathematical explanation of all factors related to spring design as well as examples. Also, just about every type of spring imaginable is explained including hot coil, volute and cantilever springs.

The book is divided into four sections.

Part 1—Spring Materials and General Considerations
Part 2—Practical Design of Helical Compression and Extension Springs
Part 3—Design of Other Types of Springs
Part 4—Basic Theory for Mechanical Spring Design

One of the better aspects of this text is the treatment of what constitutes optimal designs—what’s good and what’s not so good. All the theory on the planet is of little use without warnings and limitations of the basic design consideration to what’s safe and long-lasting. Critical applications hinge on the limits that define what will function in both force and stresses/life.

The first printing of “Mechanical Springs” was in 1944 and the second printing was in in 1963. When I searched Amazon, it listed 1980, so I do not know if there was yet another printing. All my copies show 1963. What I do know is that the text is rooted firm in both practical and theoretical approaches, which transcend times and dates. The latest updates included additions of new materials at the time, which are still relevant. That is another up-side of this text—since designs are rooted in mature mathematics, applying new material modulus and heat treatment should yield pertinent results.

Another key indicator of this work is the endorsement by the Spring Manufacturers Institute, which is the key governing body relating to design and tolerancing for a number of springmakers, both USA and foreign.

Their opening remarks include the comment, “Mr. Wahl’s fine work has endured over the years and remains today the standard of Excellence for the spring industry.”

The comment is then signed-off by the SMI Technology Committeemembers of the time of the book’s printing.

The next thorough spring design resource is SAE’s Society of Automotive Engineers (SAE), “Spring Design Manual.” This work has its primary focus on stresses as seen by automotive and vehicular applications. It also has a lot of data on leaf springs since those suspension methods are still a large part of the automotive and fleet trucking business.

It also has data on both torsion bars and stabilizer bars, which have special applications in automotive and trucking as well as real-world application history. Information on shot peening as it relates to large compression springs is concise and extensive. It is also extremely well illustrated.

Speaking of illustrations, one of my favorite resources is “Spring Design and Application” as published by McGraw-Hill, 1961, and authored by Nicholas P. Chironls. This reference is akin to the favorite book you had as a child that you never get over. This book is aged, but imaginative. It’s quite clinical in its mathematics, but has a charm and more great applications and drawings as no other spring-related text. It’s just visually chocked full of things to look at and after 25 years of searching its pages, I still find something new as well as unique, creative applications from days gone by…if you can find a copy. If you can, buy it!!

By: Randy DeFord, Engineering Manager Mid-West Spring & Stamping