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Winch Operations: Part 1
RON MOORE Firehouse Magazine
SUBJECT: Winch Operations at Rescue ScenesTOPIC: ?Red Flag? Moments During Winch Operations
OBJECTIVE:
Understand conditions and situations during winch operations that indicate unsafe acts and/or diminished safety. These are referred to as ?Red Flag? moments.
TASK:
Based upon study of a real-world cable failure incident and past experiences, create a list of potential ?red flag? moments that can exist at any winch line operation. Develop operational winch guidelines to insure safe and efficient winch line operations at incident scenes.
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
Photo By Ron Moore
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.
Red Flag: The norm for this type of recovery
is to pump off the liquid, called off-loading, to
minimize the possibility of a spill of any
liquids into a nearby storm drain during
vehicle recovery. If nothing is leaking from
the tank now, then nothing should be leaking
from the tank once it is finally removed from the scene.
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.
Red Flag: Note that the tank is resting on a short, but relatively steep downhill slope. An uphill
pull to recover this fully loaded tank and truck will require greater effort and place more strain on
the pulling system.
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.
Photo By Ron Moore
Photo By Ron Moore
Red Flag: Note that at this point, because
the tow operator has decided to attempt to
recover the loaded tank and truck, the
resistance of the load being pulled has
caused severe twisting of the truck?s
chassis. This is not good. You don?t normally
see heavy steel-frame rails bend to this
extent during a truck recovery done by
professional recovery personnel. This is a
sign that a lot of energy is being put into this
low-angle pull.
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.
Red Flag: This is truly a ?Red Flag?
moment. Something is about to go wrong!
Just consider the potential energy that is
stored up in this system. The tow truck
operator is literally trying to tear the truck away from the fully loaded tank.
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.
Red Flag: Personnel standing too close to a working winch cable line is a bad thing. If a cable
should fail or a hook or chain length fracture during the stress of a pull, the wire rope cable will
whip about violently until it loses its stored energy. The area that the failed cables can slice
through is equal to the distance from the tow truck boom to the crashed truck. A distance greater
than this in all directions should be kept clear of all personnel during the pull, no exceptions. Tell
the operator, ?I don?t care if that is your tow truck. You?re going to be killed if that winch line
fails. I?m the fire department safety officer at this scene and I won?t allow you to stand there!?
Anyone within the ?strike zone? is in great danger.
Anytime the front wheels of a heavy-duty tow
truck come off the ground, something is
Photo By Ron Moore
Photo By Ron Moore
Photo By Ron Moore
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.
Ron Moore, a Firehouse? contributing editor, is a battalion chief and the training officer for the McKinney, TX, Fire Department. He also authors a monthly online article in the Firehouse.com ?MembersZone? and serves as the Forum Moderator for the extrication section of the Firehouse.com website. Moore can be contacted directly at [email protected].
Winch Operations ? Part 2
RON MOORE Firehouse Magazine
SUBJECT: Winch Operations at Rescue ScenesTOPIC: Things You Ought to Know About Using a
Photo By Ron Moore
Winch at Rescue Scenes
OBJECTIVE:Understand the safety concerns and critical operational features of a winch when used at a rescue scene
TASK:
Using the winch and accessory equipment operated by your agency, develop operational winch guidelines to insure safe and efficient winch operations at incident scenes.
This article could actually be titled ?Things
You Probably Don?t Know About Winches.?
Each of the items listed is an important safety
or operational point for any agency to
consider when performing equipment
maintenance, conducting hands-on training,
or operating a winch system at a rescue
incident. Although not a complete listing,
these items are some of the more critical
elements of winch systems. Further details
are available from sources such as winch
system manufacturers and heavy rescue-
oriented training programs.
Before we get started, some winch
terminology must be understood:
Wire rope ? Often called ?cable? by firefighters and rescue personnel, it consists of many thin
steel wires grouped into bundles to form strands. Multiple strands of wire are then twisted
together around a core to form a complete wire-rope assembly.
Wrap ? A single coil of wire rope wound on
the drum of a winch.
Layer ? All wraps of wire rope around a
winch drum that are on the same level.
Item: The capacity of a winch decreases as
more layers of cable wrap around the drum.
Every winch has a rating; a maximum load
that it can pull with its line. For example,
yours may be rated at 8,000 pounds or
20,000 pounds. But do you know what that
Photos by Ron MooreThe ?wraps? of wire rope (commonly called ?cable? by fire/rescue personnel) create the multiple ?layers? on the drum of this rescue vehicle?s winch.
Photos by Ron MooreThe only time a winch will exert its rated capacity is when all cable is off except for the first layer. Each additional layer of cable decreases pulling power 10% to 12%. Pulling with a full drum, as shown, would be at only 50% of the rated winch capacity.
really means? All winch ratings are actually ?first- layer? ratings. This means that the maximum
pulling capacity of a winch is only at the first layer; when all cable is off the drum except the very
first layer of cable. The capacity of a winch decreases as more layers of cable wrap around the
drum. For example, a typical fire department 8,000-pound winch using three-eighths-inch wire
rope has actually five ratings, depending upon which layer of cable is doing the pulling:
1st layer ? 8,000 pounds 2nd layer ? 6,700 pounds 3rd layer ? 5,700 pounds 4th layer ? 5,000 pounds 5th layer ? 4,500 pounds
As a rule of thumb, for each layer of wire rope on the drum, deduct 10% to 12% off the rated line
pull (http://www.innovation-engineering.co.uk/theory.htm). Generally, when all the cable is on a
winch, the pulling capacity is only one half (50%) of its full rating. The change is due to the cable
that is pulling the load actually getting farther
away from the axis or center drum of the
winch ? a good reason to pull off lengths of
wire rope and rig up a pulley system with
your winch. The mechanical advantage can
double your pulling power and get the pull
closer to the first-layer winch rating. Also
notice as cable builds up layers on a winch
drum, the speed that the line moves
increases to nearly double the first-layer
speed.
Item: You have to always leave some
cable on the drum.
Always leave a minimum of five wraps of
wire rope on the drum at the bottom layer to
achieve a rated load. This is a safety feature
that keeps the line from pulling completely
off the winch drum. Five layers on the drum is the minimum!
Item: There are good reasons to place a heavy canvas or duck tarp over winch lines.
Part 1 of this series described an actual incident where the failure of a tow truck?s cable under
load instantly caused 35 feet of broken cable to release uncontrollably. Winch operators should
always make sure that everyone keeps well back and away from any winching activity. It is good
practice to use a heavy blanket or heavy weight tarp over the wire rope during a pulling set up. In
Photos by Ron MooreTwo safety problems are evident as this tow operator attempts to right a side-resting pickup truck. First, he is standing in the line of fire if the winch cable would fail. Second, with the back of his hook facing up, the hook would go airborne right toward his position if it were to fail.
that way, if a rope failure should occur, the weight of the tarp will act as a damper and help
minimize the whipping of the broken cable. For operator safety, raising the vehicle?s hood can
also give some protection should the rope break. Also, during winching, the tarp acts as a visual
warning to rescue personnel, preventing them from walking into or tripping over the wire rope.
Item: When a rescue hook fails under load, it moves in the direction of the back of the
hook.
In the event of a hook failure under a load, the broken hook will move violently in the direction of
the back of the hook. Winch operators must remain within the working load limits of their
equipment. Secondly, operators must make sure the hook is in the correct winching position. The
hook should always be placed so its back is either facing the ground or facing away from the
winch operator (http://wreckmaster.com/World/Recovery12.htm).
Item: Winch cable on an electric-powered winch should have slack in it when you first
start to pull.
An interesting procedure that I believe very few fire/rescue winch operators are aware of is the ?
slack in the line? rule for electric winches. As stated in the Army?s official HUMMER training
manual (Army HUMMER training manual TM 9-2320-280-10 2-134.2), operators are advised to
allow one foot of slack in the winch cable prior to start of winching operations. This allows time for
the electric winch motor to get up to speed for maximum pulling power.
Item: Winch cable too small in diameter
or too large for your winch is unsafe.
It is important for safe operations that the
diameter of the winch line is proper for the
winch you are using. There is a formula for
determining if your winch has the proper
diameter cable.
The largest recommended wire-rope size
should be no larger than one-eighth the
cable drum barrel diameter
(http://www.innovation-engineering.co.uk/theory.htm). Check it out with your winch and cable.
See if they match.
Item: Wire rope is identified by two numbers.
Two numbers, such as ?6 x 19,? are used to classify the construction of all wire rope. One
number indicates the number of individual wires that make up a strand. The other number
indicates the number of strands wrapped around a core to make up the complete wire rope. For
example, a winch cable may be described as ?6 x 19 wire rope.? This popular rescue winch wire
rope, also used by many tow agencies nationwide, consists of 19 individual wires twisted into
each strand of cable. The number 6 indicates that a total of six strands are then twisted together
to form the wire rope.
Item: Some wire rope or cable on a winch isn?t actually all steel.
It is possible that a steel winch line can have a natural fiber comprising center core. Referred to
as a fiber core wire rope, it is composed of wire wrapped around a fiber or man-made center. The
fiber core can be manila, jute, sisal or more recently, man-made polypropylene, offering better
resistance to rotting, drying out and other forms of deterioration. Fiber core ?cushions? the steel
strands during operation. As the core is usually impregnated with lubricant before manufacture, it
continues to act as an internal lubricator during the operation of the rope. Fiber core is less violent
than steel core as it recoils after failure (breaking).
Photos by Ron MooreThe weight of a heavy tarp placed over winch cables during a pull will act as a damper and help minimize the whipping of the cable should a cable or hook failure occur.
Item: A winch cable must be inspected,
lubricated, and properly maintained.
On aircraft carriers, a 20-ton airplane hits the
deck at 120 mph. It is brought to a halt in a
short 200 feet when it hooks one of the four
cables stretched across the carrier. Each
catch wire is used exactly 100 times before it
is replaced. That?s preventative
maintenance at its best (?Aircraft Carrier,?
Nova. Airdate: Jan. 7, 1997).
Fire/rescue winch cables aren?t replaced after 100 uses; many aren?t even inspected or
maintained properly after each use. There are some common-sense things to do regarding
maintenance of your winch line. Visual inspection for the first appearance of ?fishhooks? in the
wire, stretching, kinks or flattened sections provides a good indicator of wire-rope damage.
The line should be lubricated on a regular basis. Recommended lubricants and proper application
are a must. Wire rope manufacturers can provide specific details. Winch line should be cleaned
with a wire brush, compressed air, or steam in conjunction with application of a recommended
cleaner-solvent to remove old lubricant and debris. It is better to lubricate lightly and frequently
than it is to apply heavy doses of lubricant on an infrequent basis. You can also reverse the cable
on the drum periodically.
Item: Wire rope stretches and gets thinner as a load is placed on the line.
All steel wire ropes will stretch during their initial use. This is known as ?constructional stretch?
and is caused by the tightening of the wires and strands into their respective cores. An
approximate elongation of six inches per 100 feet can be expected in a six-stranded rope.
Excessive stretch beyond this should be cause for replacement.
Also, inspect your winch line for any lengthening or reduction diameter. These are signs of severe
stretch, which occur as a result of overloading or due to loss of strength as the cable approaches
the end of its life cycle. Authorities report that for diameters up to and including wire rope, there
can be as much as three-64ths of an inch of reduction. A reduction in diameter of up to one-16th
of an inch is acceptable for wire-rope diameters of seven-eighths of an inch to 11?8 inches.
Photos by Ron MooreThis winch system is ?out of service? or should be. Among other problems, the wire rope is damaged in several spots and the cable layers are all tangled on the winch drum.