Trailers - How to Design & Build

Introduction to the Final Edition

This is the third major version of this book, and we believe it will be the last. Over 14 years, we wrote, drew, recalculated, and restructured until we realized that one book could not hold everything. We had to divide the material into three volumes to make it complete and useful. Volume One has six chapters. It focuses on what people usually think about when building a trailer: layout, materials, and design basics. Volumes Two and Three dive into deeper technical topics—like frame strength and towing performance. These areas are essential but often overlooked. If you truly want to design and build your own trailer, you should read and understand all three volumes. This set gives you the basic tools to get started and keep going safely and confidently. Most of this content focuses on trailers under 7,500 pounds. If you are working with heavier models, consult an expert to guide you through specific challenges.

What Each Volume Covers

Volume One has six chapters that guide you through the early stages of trailer design. The first two chapters offer an introduction to trailer building. Chapters Three, Four, and Five cover the main components. Chapter Six walks you through cutting, layout, welding, and painting. The appendix lists major suppliers. If you don’t know where to start, begin there. You can also find inspiration in trailer parks or recreational areas. Look at trailers that interest you. Use those as starting points, and then apply the warnings and suggestions in this book to evaluate and improve the designs. Be careful—some trailers look well built but are not. This book helps you spot issues and fix them. It teaches you how to build something safe and functional. The goal is not to copy, but to learn, adapt, and create something better. Start smart, and keep safety in mind throughout the process.

A Word About the Author’s Experience

This book reflects the author’s experience in building trailers over many years. It does not claim to be the only way or the best way. There are other methods that work just as well. A book gives you information, but not supervision. That’s the tradeoff. You can choose how to use what you learn, but we cannot check your work. Because of that, we cannot take responsibility for your results. As you read, be sure that the information makes sense for your project. Think carefully before applying anything. If you don’t understand something, ask someone with experience. Use common sense and rely on expert advice when needed. Building a trailer involves real risks, and mistakes can be dangerous. Always check and double-check your decisions. Take the time to think through each step. It’s your responsibility to build something safe. This book is only a tool to help you do that.

Acknowledgments

This book would not exist without the support of many people. Rich McCormack of Newport Press helped shape the first concept. Wendy Jo Block, a journalism expert, and R. E. Williams, a technical expert, helped with editing and spotting small errors. Delores McTaggart typed the first drafts on a typewriter. In 1987, we moved the work to a Macintosh computer. Debbie West and Paulette Kelly revised the drafts many times. Their dedication turned one book into two volumes of nearly 200 pages each. Some drawings came from personal knowledge. Others were based on help from suppliers and engineers. Kruse Feed & Supply helped us weigh alfalfa bales. Century Wheel & Rim shared comments and reviewed calculations. Ken Foster and Merle Bolden checked technical data. Other companies contributed photos, data, tools, and parts. Their help filled gaps in this book. The author’s 18 years in trailer manufacturing also built a strong base of experience.

Technical Contributions and Resources

Many manufacturers supported this work by offering expert input. Norm Reynolds of Torax wrote a detailed letter about torsion axles. Don Boerger and Vic Rosengarten of Henschen offered data and advice. Vince Scott from UCF and Mike Platz from AL-KO added key insights. Mike also sent data on mechanical brakes used in Europe. Ron Haase at Dutton Lainson provided engineering drawings and product info. John Bechtold at Unique Functional Products shared photos and took time to explain bearing protectors. Tom Kneiss from Hammerblow referred us to AgServ West. John McKeon, Jr. sent trailer jacks for photography. Thom Perry and Julie Dunham from Superwinch shared charts on winch strength. Charles Perry followed up with a helpful letter. Most photography came from the author’s collection or was taken specifically for this book. Some images came from company libraries. Steve Cashion provided a photo of the Mubea ironworker. All these contributions made this book stronger, more accurate, and more complete.

Safety First, Last, and Always

The purpose of this book is to increase trailer safety, not reduce it. Knowledge helps you build safer, more reliable trailers. But not all knowledge is in this book. There are too many variables to cover everything. This book offers specs and guidelines, not step-by-step plans. You decide how to use the parts and ideas presented. The entire system, including the tow vehicle, must be part of your thinking. What you build is your responsibility. Improving trailer performance may affect the tow vehicle or stress the trailer in new ways. Volume 2 and 3 cover these issues with detailed calculations and concepts. Always test a new trailer in a safe, open space like an empty parking lot. Avoid busy roads until you’re sure the trailer handles well. Watch for problems and listen closely. Instability may not show up right away. Wind, hills, or passing trucks can cause trouble. Increase speed slowly. Fix any problem immediately—don’t ignore it.

Your Responsibility as a Builder

You choose the materials, methods, and combinations. We cannot control those choices, so we cannot accept responsibility for the outcome. Building a trailer for public roads is serious work. Poor design or careless construction can lead to accidents. While few laws restrict what you can build, common sense must guide your process. You must also be honest about your own skills. Don’t take shortcuts. Don’t guess when safety is on the line. Use this book to learn, prepare, and check your work. When in doubt, ask a professional. Test everything before going on the road. Use your knowledge to build something solid and safe. That’s your goal. This book is here to help, but it’s only one part of the equation. The rest is up to you.