Stop “Hammering the Deck”

By Randall C. Resch

A town’s newspaper headline read, “Tow Truck Spews Hydraulic Liquid, Dropping Car Near Roundabout.” To that I say, “OMG, is the world coming to an end?” When this happens, towers likely know what the cause was. Unfortunately, in this situation, the operator admitted he was “hammering the deck,” causing an underside line to blow.

It’s one of those unintended “Oh Crap” moments when a carrier’s actions “barf” gallons of hydraulic fluid onto the pavement. What happens next is that telltale flurry of workers hastily dumping kitty litter atop the oozing flow.

Do you know what Pascal’s Law is as it regards tow truck hydraulics? Pascal’s Law describes “the process said to create extreme pressure when dense fluids are forced through small-diameter hoses and tubes under pressure.”

There’s a basic principle that governs hydraulics; a principle learned hundreds of years ago. French mathematician Blaise Pascal formulated the theory that “pressure applied to confined liquids acts at right angles to the surfaces of containers holding the fluid.”

Mr. Pascal introduced his concept, suggesting that “oil is virtually non-compressible, where forces applied to the end of an oil-filled tube (or hose) instantly flow to the other end.” What does this mean?

Simply put, if a tow truck’s hoses or tubes are defective, liquids under pressure are bound to burst through. My explanation suggests that hydraulic hoses are “wear items” and require regular inspection and replacement to ensure optimum conditions against bursting.

What’s That Noise?

A similar situation occurred when an operator worked his aged carrier running at high-idle RPM with the PTO engaged. With the carrier situated across from a rental company’s entry, he was actively loading a small forklift when, without warning, a loud “Pssssshhhhht” audibly indicated the sound of a bursting hydraulic hose.

In an instant, the carrier’s winch and deck operations were disabled. A billowing cloud of light-gray smoke filled the surrounding area while a puddle of nasty brown fluid oozed from beneath the carrier’s deck. Because the PTO was still turning, the carrier spewed gallons of fluid before the truck was shut off.

As expected, one of the rental office employees panicked and dialed 911, claiming, “The tow truck’s on fire.” Minutes later, a screamin’ fire rig arrived looking for a fire to fight, but quickly determined the smoke was the direct result of hydraulic fluid soaking the carrier’s hot exhaust. Because the carrier showed signs of extreme wear and poor maintenance, inspectors discovered that a hydraulic hose had repeatedly rubbed against the truck’s frame, sawing a slice into the hose and causing it to burst.

If this situation has ever happened to you, you know just how embarrassing that moment is when all eyes are on you and your still-smoking truck.

Deck Killers

Especially true in carrier operations, one of the more difficult tasks is off-loading vehicles that won’t roll due to all-wheel drive, missing tires and wheels, or wrecks having extensive damage. For carriers not equipped with skates, dollies, or even soapy water, operators resort to “slam-banging” carrier decks back and forth. Ya’ got ta’ know, it’s killin’ the deck! Don’t do it!

The repeated “hammering action” is regularly associated with blown hydraulic lines. Although modern hydraulic systems are designed with flow dividers and relief valves built into PTO systems, hoses aren’t designed to take the abusive beating created by “hammering carrier decks,” in likeness to Pascal’s Law.

Hydraulic lines are designed to have great holding power under the PSI produced by a system’s PTO pump. Factors such as temperature and fluid type affect a line’s pressure tolerance, where high-pressure hose failure occurs between operational ranges of 2,100 and 5,000 PSI, depending on the application. When deck hammering is initiated, there’s no telling when hoses will burst.

Resistance Factors

It’s important that towers learn how to use skates properly. For towers who understand the difficulties associated with recovery winching, the same holds true for non-rolling vehicles atop a carrier’s deck. When vehicles don’t roll, the obvious reasons are influenced by the casualty’s weight, combined with friction, lack of motion, and incline.

Equally important, that doesn’t mean soaping the deck or disconnecting the casualty from attachment bridles while raising the deck full-tilt to get vehicles to slide off. The latter is an incredibly dangerous technique typically practiced by lazy and unskilled operators. Note: To do so goes against the grain of industry safety and OSHA guidelines.

In the opening scenario, it occurred in a small Florida town where a local flatbed carrier had one of its hoses let go. But when it’s a “slow news day,” of course some absurd headline will make it to the five o’clock news. Remember, if hoses aren’t maintained, it’s only a matter of time before a line blows. Perhaps the bigger question is, “What’s the cost of cleanup gonna’ be?”

Operations Editor Randall C. Resch is a retired, veteran, California police officer, former tow business owner and industry advocate. As consultant and trainer, he authored and teachestow truck operator safety courses approved by the California Highway Patrol. For 57-years, he has been involved in the towing and recovery industry. In 29-years, he has contributed more than 800-safety focused articles for American Towman Magazine, TowIndustryWeek.com and POLICE Magazine. He is a frequent seminar presenter and beauty pageant judge at tow shows. In 2014, 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.