The Dangers of Unguarded PTO Components

By Randall C. Resch   

A newbie tower in Texas purchased a vintage wrecker from a small town tow company and shared with me his plans of hoping to grow his own company. He told me he used it around town for farming tasks on his parent’s rural property. He excitedly asked, “Would you have a look at it?” With interest, I moseyed to the old tow truck noticing (first thing) the vintage wrecker’s winch was missing its topside power take-off (PTO) drive chain cover.   

Although he was aware the cover was missing, he was eager to learn what was necessary to “make the old truck safe.”   So, in a safety’s sense, I explained that the tow truck’s wrecker equipment came originally outfitted with a PTO chain cover. I sadly advised that finding a replacement wouldn’t be likely, but he could have a metal shop build a replacement.   

While modern wreckers have advanced hydraulic and electric drive-systems, there’s plenty of old school wreckers still being used across America. If yours is an old-style wrecker or carrier with chain or shaft-driven PTO, this narrative should be of interest to you. 

PTO History 

Experimental PTOs were reportedly built as early as 1878, with homemade versions constructed over subsequent decades. It wasn’t until 1918 that Edward A. Johnston, an engineer with International Harvester Company (IHC), designed the first PTO for attaching farm implements to tractors. 

Mr. Johnston suggested a farm tractor’s PTO system could power implements and attachments between a tractor’s “tail shaft” connecting its engine to its transmission. As early PTO systems gained popularity and a means to power mechanical drive trains, it brought value to other service applications that powered dump truck boxes, fire truck pumps, cement truck barrels, tow truck winches and a bevy of equipment types. 

Although the system became highly desirable, PTO’s and their use led to hundreds of injuries and fatalities. According to the National Safety Council, they reported six percent of US tractor related fatalities (in 1997) involved PTOs. Farmers, children and workers didn’t foresee the dangers of unprotected shafts spinning upwards to 1,500 rpm. 

Beware the Dangers 

OSHA investigations identified this class of accident having to do with workers working in close-proximity to unguarded PTO components, or their extremities were dragged into spinning shafts because of baggy clothing and loose flying hair. The Internet is full of incidents where workers and equipment operators were violently injured or killed being caught in PTO components.   Early tow truck mechanisms derived power from the truck’s engine to a connecting driveshaft. Mechanically, a large chain connected a PTO pump to the wrecker’s winch. A drive chain connected two gears’ between both systems where a spinning main (drive) shaft caused the winches gear’s to turn.  Early tow truck mechanisms derived power from the truck’s engine to a connecting driveshaft. Mechanically, a large chain connected a PTO pump to the wrecker’s winch. A drive chain connected two gears’ between both systems where a spinning main (drive) shaft caused the winches gear’s to turn.  

Safety guards were strategically mounted so to cover dangerous spinning parts. When mounted in proper locations, guards kept objects, operators and personnel from being entangled in a PTO’s chain, shaft, or drive sprockets. Especially dangerous to tow operators are components that are openly exposed when safety covers are removed. Regardless as to your tow truck’s system, consider seven simple safety recommendations: 

1. Before working on systems, chock tires, place transmission in-gear or park while applying the E-Brake 

2. Always disengage the PTO  

3. If a guard is removed, situate a warning notice at the driver’s station or steering wheel. 

4. Turn engine “Off” and remove keys before exiting the cab. Removing ignition keys ensures no one can pre-maturely start the truck while maintenance is performed. 

5. PTO guards should never be removed during wrecker, boom and winch operations.  Inspect frequently to ensure guards are in good condition. Inspect frequently to ensure guards are in good condition. 

6. Keep away from PTO components. Remove loose fitting clothing to avoid getting caught in spinning components. Remove loose fitting clothing to avoid getting caught in spinning components. 

7. Never operate a tow truck when guards are removed, defective or missing. An unprotected, spinning PTO shaft or uncovered components can result in great bodily injury or death. My best advice: stay far away from an operating system.