Winch Operations: Part 1

Sometimes, it takes a near miss to get you thinking just how close you came or just how little you know about something that could kill you. Such is the case after a tow truck winch cable failure occurred at a truck crash scene recently. In this situation, the cable failed violently and could have killed two people right before our very eyes. By relating this story to you, it is hoped that the next time you are present at a scene where a winch cable is being used under load, you’ll remember this story, set up a safe scene and avoid a near miss like we had.

The vehicle that crashed was a 10-wheel truck outfitted with a tank to haul waste grease and oils from food establishments. At an expressway on-ramp, the driver lost control, rolled the vehicle onto its roof and slid to a halt in a ditch at the side of the road. Civilians removed the injured driver just as the first fire department units were arriving on scene. There was a small spill of fluids from the truck itself that were quickly contained by fire department personnel. The tank remained intact, although it was almost completely dislodged from the truck chassis.

A local wrecker company was summoned by the police to recover the overturned truck. Rather than off-load the tanker, the tow truck operators decided to upright the loaded unit with a low-angle, dual-line pull off their heavy-duty wrecker while fire department personnel stood by. In the process, one tow cable suddenly snapped in two and violently whipped around the scene, narrowly missing two tow truck company employees. The images contained in this installment tell the story of what happened and the lessons learned.

The challenge to fire and rescue personnel who many times are standing by during these recovery operations is to analyze these images and identify the telltale “Red Flags” moments that were completely overlooked or not respected by tow company personnel. Once you know where the dangers lie at the scene of a winch line recovery operation, decide what your course of action will be for your fire-rescue personnel.

This is how first-due fire department personnel found the scene upon their arrival. Motorists who had stopped at the crash scene were pulling the injured driver from the cab through the open door. Note that the chassis of the 10-wheeler appears intact.

A view from the rear shows the waste tank almost completely torn away from the chassis of the truck. The waste oil tank did not leak; only fluids from the truck itself had to be dealt with by the fire department.

The heavy-duty tow truck operators placed their 16-ton capacity unit at a 90-degree angle to the overturned truck. They hooked one winch line high on the front axle and a second line to the rear tandem axle and began pulling the loaded tanker. This image was taken just as the second winch line was being placed in service.

The pull is now so extreme that the cab of the truck is actually being lifted off the ground. The resistance of the weight of the waste tank plus the holding strength of the one attachment plate bolted to the chassis is causing a winch overload situation.

This is the scene from the opposite side just a few seconds before cable failure. The operator of the tow truck is at the rear of the truck. His partner is standing in the foreground with his back to the camera. As the stress of the pull became so great, the front wheels of the tow truck actually rose approximately 18 inches off the ground.

Anytime the front wheels of a heavy-duty tow truck come off the ground, something is probably wrong, as it was in this case. At that moment, the cable closest to the camera violently failed. The failure occurred about four feet beyond the pulley block at the top of the tow truck boom. The 35 feet of broken wire cable shot like a bullet toward the overturned truck, slamming into the undercarriage.

This failure location actually saved lives. If the cable had failed closer to the damaged truck or if the hooks or chain had fractured, the cable would have whipped backward toward the tow truck. The tow truck operator and his partner were both within the strike zone of the cable had the failure occurred at this location in the line.

A closer look at the end of the tow cable shows the tremendous, almost explosive result of sudden cable failure. The stored energy built up within the cable is instantaneously released. It is that release of energy that creates the winch line “flying cable” potential.

The line failed several feet from the tow truck boom. Because of that failure point, the free end of the cable traveled away from where the two tow truck personnel were standing. Had the failure been at a different location, the results would have been fatal.

The challenge is to develop guidelines describing what we could do at a future incident anytime a winch cable is being used at an incident scene.