By Chris Daly
In winter, the need to recover an apparatus trapped in deep snow may become likely. Understanding safe and effective methods for recovering stuck vehicles is an often overlooked facet of driver training programs.
There are typically three types of recovery operations:
- The trapped vehicle uses its vehicle-mounted winch to pull itself back onto the roadway.
- A second vehicle uses a vehicle-mounted winch to pull the trapped vehicle back onto the roadway.
- A second vehicle uses a recovery strap to “snatch” the trapped vehicle back onto the roadway.
Each type of recovery will involve different methods and equipment. Prior to discussing these operations, drivers must understand recovery equipment.
While tow straps, recovery straps, and tree trunk protectors may look the same, they serve different purposes. It is not unusual for all three types of recovery equipment to be kept in the same compartment. Many firefighters do not realize that each item has a different application. Using the wrong recovery equipment may result in serious injury or damage to the vehicle (photo 1).
|1 This brush truck is equipped with a well-organized winch kit. The kit contains two rigging straps, a choker chain, and D-shackles. Using improper equipment to perform a winch recovery may result in damage or injury. (Photos by author.)|
Tree Trunk Protector: Tree trunk protectors are typically made of nonelastic nylon webbing and may be referred to as “rigging straps.” These straps are wrapped around a tree or bombproof anchor point and secured with a clevis pin or D-shackle. A winch hook is attached to the D-shackle to pull the vehicle free. Be aware that sharp points on an anchor point may cut or tear the nylon webbing.
Choker Chains: Choker chains are also used as anchor points for winch operations. The advantage to a choker chain is that it will not tear on a sharp corner like a nylon tree trunk protector. The disadvantage to a choker chain is that it may damage the anchor point. Depending on the situation, this may not matter (photo 2).
|2 A choker chain is wrapped around a solid tree to create a bombproof anchor.|
Tow Straps: Tow straps are nonelastic and usually made of polyester. Tow straps are used to tow a free-wheeled vehicle behind another vehicle. They should not be used to “snatch” another vehicle during a recovery operation. The inelastic properties of the tow straps may cause them to snap.
Recovery Straps: Recovery straps are used to pull or “snatch” a stuck vehicle free. Recovery straps are usually made of Nylon and have elastic properties that allow them to stretch. When the strap stretches, the stretching energy is transferred to the stuck vehicle, which helps pull the vehicle onto the road like a rubber band. Recovery straps should never be used as anchor points because of their elastic properties.
Strap Ratings: As a rule of thumb, one inch of strap webbing equals approximately 10,000 pounds of load. A four-inch-wide piece of strap webbing should be rated at approximately 40,000 pounds of load. As we require a 2:1 safety advantage for any winch or recovery operation, a 30,000-pound fire apparatus would require a six-inch recovery strap.
Winch: It is important to know the vehicle’s winch capacity. Most winch manufacturers recommend multiplying the weight of the vehicle by a factor of 1.5. A 20,000-pound vehicle would require a winch rated at 30,000 pounds.
Keep in mind that the winch capacity is affected by unwinding the winch rope-it’s not called “cable.” Maximum winch capacity is rated with the first layer of winch rope wrapped on the drum. As the drum winds the rope back into itself, the pulling capacity of the winch will decrease. For most winches, each layer of wrapped rope on the drum reduces the rated capacity by approximately 10 to 15 percent. Keep a laminated chart in the vehicle so members can quickly reference the rated capacities when needed (photo 3). Also keep in mind that prior to using a winch, stretch the rope according to the manufacturer’s recommendation.
|3 The rated capacity of this winch, based on the number of drum wraps, is printed directly on the winch.|
In situations where the anchor point is close to the winch, consider using snatch blocks. Snatch blocks will increase the amount of rope that is unspooled, thereby increasing the capacity of the winch. Snatch blocks will also create a mechanical advantage that will increase pulling capacity. There are countless ways to set up a mechanical advantage system, and these methods should be drilled on before a recovery operation takes place.
Vehicles can be equipped with an electric winch or a power-takeoff-driven hydraulic winch (photo 4). Electric winches will have an advantage if the vehicle is stalled or disabled, as they will still work if there is enough battery power left in the vehicle. In this scenario, keep a close eye on voltage gauges, as the battery power may not last very long.
|4 This vehicle is equipped with an electric winch that can be mounted to the front or back of the vehicle, depending on the need.|
Electric winches may be more prone to overheating than hydraulic winches. During a long pull, ensure that crews stop the winch from time to time to cool down. A hydraulic winch does not place as large a load on the electrical system and may not be as prone to overheating as an electric winch.
Tow and Recovery Points
Fire apparatus operators must know the recovery points on the frame of the apparatus. Stock vehicles, such as ambulances or command units, may have hooks and rings that appear to be recovery points. These points are only meant to be used to secure the vehicle to a delivery truck while en route to a dealer. If the vehicle is only equipped with delivery attachment points, the fire department should add properly rated recovery points to the vehicle. Check the owner’s manual to determine the proper recovery points for a winch operation. Vehicles should have easily accessible recovery points on both the front and back of the vehicle.
Anchor Points for Recovery Operations
Recovery operations require strong and bombproof anchor points for winch operations. During a winch operation, never wrap the winch rope around an anchor point and then connect it back onto itself. Wrapping winch rope onto itself will result in winch rope damage and possible failure. Instead, wrap an anchor strap, such as a tree protector or choker chain, around the anchor and secure it with a clevis pin or D-shackle. Secure the winch rope to the clevis pin or D-shackle. Do not use a recovery strap to wrap around an anchor point!
When choosing an anchor point, do not use dead trees, loose boulders, or any other object that is not firmly in the ground. Depending on the circumstances, a second vehicle can be used as an anchor point. However, you must ensure that the anchor vehicle is chocked and the parking brake is set. The anchor point should allow the winch rope to stay as straight as possible so that it properly winds itself back on the spool. If the winch rope is allowed to cross over on itself, it may result in damage to the winch rope.
Using a Recovery Strap
When using a recovery strap, attach the strap to secure recovery points on both vehicles. Never tie recovery straps in a knot. Instead, choke the strap on itself or attach it to a recovery point using a clevis pin or D-shackle. Never attach a recovery strap to a tow ball or vehicle component, as it may break loose and become a dangerous projectile.
When the drivers are ready, the recovery vehicle should begin gently moving in first gear. The recovery vehicle must avoid hard or sudden accelerations that may “jerk” and damage the trapped vehicle. When the recovery vehicle takes up the slack in the strap, it will begin to pull the trapped vehicle back to the road. The trapped vehicle can provide assistance by applying power as appropriate.
Using a Winch
Winch operations can be dangerous. Ensure that the winch and winch rope are secured to a bombproof anchor and neither component is overloaded. By not securing the winch rope or by overloading the system, the rope may break or come loose. A broken winch rope will create a dangerous whip that will seriously injure anyone in its path.
Never touch a winch rope that is under tension, and make sure that no members are standing in the path of the rope. Inspect the winch rope for any damage prior to making the pull, and make sure to wear gloves at all times, as a burr or slice in the rope will cause serious lacerations. When pulling the rope to the anchor or holding it as it respools, make sure to hold the rope with a hook strap to prevent hand injuries should the winch be engaged accidentally.
Place a heavy coat or mat on the winch rope during the pull. This will dampen the whipping action of the rope should it fail. Some experts also recommend using two dampening devices: one eight to 10 feet from the drum and another eight to 10 feet from the anchor point. This will give both ends of the broken rope a dampener and better absorb the whipping action. Raising the hood of the vehicle will also provide added shielding for the driver in the event of a rope failure (photo 5).
|5 The hood of the vehicle is raised to help protect the windshield and the driver should the winch rope break during the pull.|
When using an electric winch, it is helpful to leave approximately one foot of slack in the rope. The slack will allow the winch to wind up to full rpm before it begins pulling the load. Once the winch takes the load, it will be at full power.
When using a second vehicle to winch a stuck vehicle back onto the road, make sure that the winch rope is properly secured to a recovery point on the vehicle. Do not attach the winch rope to vehicle components such as struts, bumpers, or axles. Doing so may result in serious damage to the stuck vehicle if the pull should fail. If the vehicle is equipped with a tow ball, do not attach the winch rope to the ball. A tow ball is made to handle the downward force of a trailer tongue. Pulling on the tow ball may cause it to break off during the pull, creating a dangerous projectile.
It is also helpful to set the pull so the anchor strap is attached to two recovery points on the vehicle. This will help spread the force over the stuck vehicle rather than concentrating the pull on a single point.
Once the pull begins, ensure that the winch rope winds tight and flat on the winch drum. Make sure that the rope does not cross over itself on the drum or stacks to one side. Make sure to leave at least five wraps of rope on the drum. This will ensure that the connection point between the rope and the drum does not absorb all of the pull. Instead, the pull will be spread out across the drum.
Keep in mind that how deep you are stuck and the material you are stuck in will affect the force of the pull. Pulling out of a deep material, like mud, will be more difficult than pulling a vehicle across pavement or grass. The slope that you are pulling a vehicle against will also affect the required force of the pull.
Now that you are well versed in rigging, take a walk out to the engine bay and figure out what you have! Write the information on the straps with a permanent marker and be sure to tell everyone else.
CHRIS DALY is a 19-year police veteran, currently serving as a patrol supervisor in West Chester, Pennsylvania. He is an accredited crash reconstructionist and a lead investigator for the Chester County (PA) Serious Crash Assistance Team. In addition to his police duties, he has served 26 years as both a career and volunteer firefighter, holding numerous positions including assistant chief. He is a member of the editorial advisory board for Fire Apparatus & Emergency Equipment. Daly has also developed an emergency vehicle driver training program called “Drive to Survive,” which has been presented to more than 15,000 firefighters and police officers at more than 380 emergency service agencies across the United States.