Anchoring Techniques

Plus Tips on Picking the Right Equipment

By Terry Abejuela

When performing vehicle recovery operations you must be able to securely anchor the recovery vehicle. You may need to use deadman anchors (any object buried in the ground that’s used as an anchor) to move the casualty vehicle to the location you desire. If you correctly calculate the load on the recovery vehicle and anchors, and ensure they are able to resist that load, then the casualty vehicle will move when winching effort is applied. So good anchoring techniques will help you achieve a safe and successful recovery.

The first thing to determine is the total amount of resistance to move the casualty vehicle. This step is critical to doing an effective recovery. Once you know the total amount of resistance, you will be able to figure out how much load will be applied to the truck and to your anchors, based on your rigging plan. When tow operators are asked to recover a vehicle, the information obtained before arriving at the scene depends on what the customer is able to provide. The casualty vehicle description and condition, as well as scene description, are critical to choosing the correct recovery vehicle to send to the scene. Use probing questions to try to get as accurate a description as you can. Get detailed information about the casualty vehicle, terrain, slope, and surroundings such as trees, boulders, roadway conditions, and access. Also find out weather conditions, both current and at the time of disablement, and how far the casualty vehicle is from the roadway. These are all factors that may help you determine the type and size of the recovery vehicle that will be needed. Keep in mind, you will likely need to tow or transport the casualty vehicle once it has been recovered back to the roadway.

Allowing For Misinformation

Unfortunately, the information we get from the customer is not always accurate, so we must be prepared to handle whatever situation we encounter. So the recovery wrecker should be capable of handling a little more than anticipated based on the information from the customer. When the customer says the vehicle is just a little ways from roadway, be prepared for it to be well off the roadway, perhaps 50 feet, 100 feet, or even more.

In addition to choosing the proper sized wrecker, tow operators should also carry equipment that can be used to increase the anchor ability of the recovery vehicle.

Any anchoring techniques used to secure the tow truck need to be in compliance with the recovery equipment manufacturers’ recommended procedures. In general you should be able to produce about 60 to 70 percent of the recovery vehicle’s gross vehicle weight in anchor ability. This of course is dependent on the type of surface the recovery vehicle is in contact with, and the type of anchoring devices you are able to utilize.

Proper Procedures

Most towing and recovery vehicles are designed to perform recovery work from the rear of the truck. Some are equipped with outriggers that increase the stability of the truck during side pulls. Some are equipped with rear spades to increase anchor ability when pulling from the rear. Make sure the rear spades are designed for anchor ability—not for vertical lifting. Using jack legs designed for vertical lifting to anchor the truck in a heavy rear or side pull may damage the jack legs.

Tow and recovery vehicles are often equipped with a supplemental brake system. In addition to the chassis manufacturer’s parking brake, some tow and recovery vehicles will be equipped with a supplemental braking system such as a Mico lock. This device is a oneway, hydraulic check valve installed on the chassis brake master cylinder that allows the operator to apply the service brakes during a recovery operation. The parking brake should always be used in conjunction with the Mico Lock.

Since Mico locks are hydraulic there is a possibility they can bleed off. Mico Lock makes a warning device that will notify the operator when the hydraulic pressure drops. It can be installed to activate the lights and or horn on the truck when the hydraulic pressure is nearing an unsafe pressure.

Additional Techniques

Other methods to anchor the recovery vehicle include scotch blocks, wheel chocks, and lumber. Some recovery vehicles are designed to use scotch blocks. These vehicles have key slots on the rear tailboard which are inline with the rear axle dual wheels. Scotch blocks with a short length of chain attached to them can be placed behind the dual wheels and the chain attached to the key slot on the tailboard. Then the truck is backed up until the chain is tight and the dual wheels of the rear axle are on top of the scotch block. When the truck is pulled rearward the scotch block digs into the surface to create more resistance. Avoid using scotch blocks on surfaces that will be damaged such as asphalt. They work best on dirt surfaces. When used on surfaces that may be damaged, use wheel chocks or lumber under the wheels to create more resistance. Elevating the recovery boom until the winch rope over the end of the boom creates an apex will apply more downforce on the rear axle of the truck, making the scotch blocks, wheel chocks or lumber more effective.

Deadman Anchors

When you are unable to create enough anchor ability in the recovery vehicle to overcome the total recovery resistance of the casualty, you may need to use another anchor to move some of the resistance load to the anchor, thus reducing some of the load on the recovery vehicle. There are vehicle, natural and manmade anchors that can be used. Other vehicles and/ or equipment at the scene may be utilized as deadman anchors.

Of course, you would need to get permission from the owner of the vehicle or equipment prior to using them. As with the recovery vehicle, you can produce approximately 60 to 70 percent of the vehicles weight in anchor ability depending on the type of vehicle and the surface it is on. Generally a tracked vehicle will produce more resistance that a wheeled vehicle.

Containers at a construction site may be able to be used. Natural anchors include trees and boulders. If you utilize trees, make sure to get permission from the land owner. Choose trees with large diameter trunks and attach lines to them as close to the ground as possible. Take precautions to avoid damage to the tree such as utilizing wide synthetic straps instead of chain, and placing lumber between the strap and/or chain and the tree.

Unfortunately trees are not labeled with a working load limit so it is difficult to determine how much load they can handle. Resistance can be increased by utilizing several trees located in close proximity to each other, and connecting them together with multiple straps or using lumber between trees.

Manmade anchors include commercially sold and home-made anchors. Some tow operators use tent stakes pounded in the ground and chained together, or a metal plate with holes drilled through it so stakes can be pounded into the ground in several of the holes as anchors.

Using Your Ingenuity

When your recovery is in the city or on a freeway, there may not be any natural anchors available so you may need to think outside the box to accomplish your mission. Some tow operators utilize the K-rails when on the freeway, and no other option is available.

For improvising anchors in the field, The U.S. Department of the Army published a manual, FM20-22, way back in the 1960s for Recovery and Battle Damage Assessment and Repair (BSAR). The newest version of this publication came out in November 2020, and you can find it on the internet. This manual has not changed much over the years, and has some great tips for constructing deadman anchors. Techniques include burying objects in the ground such as a tire, log or piece of lumber with a chain looped around it, or digging a large hole and lining it with a parachute or trap, and filling the dirt back in, and then attaching to the parachute or tarp to use the weight of the dirt as an anchor.

In sum, in order to complete a successful recovery, a tow and recovery operator will need to calculate the recovery resistance, and then use the appropriate anchoring techniques and rigging equipment for the recovery vehicle. And if needed, add sturdy deadman anchors to overcome the total recovery resistance.