Action Reaction Phenomenon

By Randall C. Resch

Much of the tow and recovery industry has developed an attitude to suggest that“If it fits it ships!”  Not only is there potential that an overloaded truck won’t steer where it’s pointed, it’s likely not to stop.  

There’s danger in overloading a wrecker or carrier. The topic bears a closer look into the natural phenomenon of “Action Reaction” when too much of a transported vehicle’s weight sits rearward of the tow truck’s rear axle.

“If it fits it ships” mentality is capable of leading to a potentially deadly scenario whereby a wheel lift wrecker can’t brake or steer.  An overloaded carrier also creates a “top heavy” imbalance above its center line.

A Question of Stability

In the news recently was an operator fatality involved in a solo carrier (rollover) crash. The news reported that a Kenworth carrier lost control in traffic, attempted to correct, traveled down an embankment and overturned. Topside on the carrier’s deck was a Ford F350, Crewcab, also totaled in the crash.

It was suggested the carrier’s load might have created an unstable load based on the Crewcab’s weight affecting the tow truck’s carrying capability. While it’s argued the carrier was well within its deck ratings, is it possible the pickup being loaded, rear end first, created an “Action Reaction” phenomenon?

Do the Math

Let’s review “Maximum Lift Capacity” (MLC); overloading a tow truck can result in the tow truck not being able to steer cleanly or stop at an intended distance. Another reference to the same consideration is the term “Safe Towing Capacity” (STC) depending on who’s explaining the procedure.

This is especially true to light duty wheel lift tow trucks and carrier decks during tow or transport when a vehicle’s weight is situated rearward of the tow truck’s rear axle. When emergency hard braking is initiated (action), the towed or carried vehicle’s weight is sitting behind the tow truck’s rear axle (fulcrum), only to push downward creating the tow truck’s steering to lift (reaction).

One can agree that it's super scary when the tow truck or carrier steers straight ahead, and no matter how hard the brakes are mashed, a subsequent collision likely is the end result.

Know the Formula

As taught in formal tow operator training, the “MLC Calculation Formula” is written: “½ the Front Axle Weight times the Wheel Base divided by the Overhang” or (1/2 FAW x WB div. OH = MLC). The process of finding Maximum Lift Capacity is simple by using the calculator mode on your cellphone or desk calculator. Three components for calculation are:

Determine the tow truck’s “Front Axle Weight,” which can befound in several locations, i.e., tow truck’s registration card, cab mounted rating plate, or “Manufacturer’s Intermediate Sticker” (MIS).

Find the tow truck’s “Wheel Base,” which means measuring (in inches) the truck’s center front axle to center rear axle

Determine the truck’s “Overhang,” the measurement (in inches) from the center of the rear axle, rearward to the wheelift’s “Pivot Pin” when the wheel lift is “Retracted”, all the way “in”

When these three components are calculated, the approximate MLC is known. MLC identifies the approximate load the tow truck or carrier can tow or transport.

For carrier loads, safety in transport recommends that heavier SUV’s and pickup trucks are loaded with heavier (engine) end, front end first and winched atop the carrier’s deck all the way forward towards the winch platform.

Doing so transfers approximately 50-percent of the towed or transported vehicle’s weight atop and forward of the tow truck’s front axle.

With the towed or transported vehicle’s weight on the tow truck’s front axle, the tow truck is better capable of steering where it’s intended to go and brake cleanly to a stop. Keep in-mind, a loaded tow truck or carrier won’t, can’t and doesn’t stop on a dime. Speeding into a roadway’s corner may likely cause the truck to overturn or fail to negotiate the turn.

The Importance Is?

“If it fits, it ships” isn’t an appropriate consideration. There’s a legal responsibility to not overload tow truck and carriers. If an over loaded truck injures or kills another as the result of overload, both criminal prosecution and civil liability may be levied against the offending tow operator.

An easy way to remember arrangement of components is to repeat: “Front, center, rear, front, center, rear!” Remembering components in this manner helps towers to calculate load capacity.

I recommend that vehicles are loaded in accordance to acceptable industry standards that doesn’t question if a load is within the truck’s proper ratings. Not only is there overload potential, there’s a good chance law enforcement will want to have a talk with the tow truck’s driver.

If you’re a tower who risks overload because of the “cool factor,” or out of sheer laziness, let this narrative serve as a friendly warning. Remember, accidents are a product of the unknown and risking an overload incident is never proper or smart.         

Operations Editor Randall C. Resch is a retired California police officer and veteran tow business owner. As consultant and trainer, he authored and teaches a tow truck operator safety course approved by the California Highway Patrol. For 51-years, he has been involved in the towing and recovery industry. In 26-years, he has contributed more than 700-safety focused articles for American Towman Magazine and TowIndustryWeek.com. He was inducted to the International Towing and Recovery Industry Hall of Fame, was the 3rd recipient of the industry's "Dave Jones Leadership Award," and is a member of American Towman’s Safety Committee. Email Randy at rreschran@gmail.com.