Extracting a Stuck Vehicle

When extracting a stuck vehicle, many factors can affect the actual pulling force needed. Read on to learn what they are.

How to Calculate Minimum Winching Effort & Minimum Working Load Limit

extracting a stuck vehicle calculation formula

When extracting a stuck vehicle, many factors can affect the actual pulling force needed, as well as selecting recovery equipment with high enough load ratings.

During a recent Iowa Corn Growers Event hosted at US Cargo Control headquarters, Tim Sanders, a Trucking and Transporation expert, and USCC business development specialist, gave an informative overview of what goes into effectively extracting a vehicle that’s stuck in the mud, sand, gravel, snow, etc.

When work needs to get done, it may seem tempting to just grab a strap or chain and pull until something happens. However, if you take a few minutes to do some simple calculations, you’ll likely save time in the long run and more importantly, help ensure the safety of those around the extraction scene.

The formula for calculating the required minimum recovery capacity

Total vehicle weight (W), additional rolling resistance (ARR), and additional gradient resistance (AGR). Once you have these calculations, you can quickly determine the recovery equipment strength you will need:

  1. What does the stuck vehicle weight, including all cargo, attachments, trailers, etc.?

    This is the “W” part of the formula.
  2. What factors will add to the pulling effort and safe working load limits required to pull the total weight of the vehicle?

    When we say “additional factors” we’re mainly talking about two things: additional rolling resistance (ARR) and additional gradient resistance (AGR)

Minimum Capacity Required = W + ARR + AGR

tim sander USCC sales and trucking gear expert
USCC Business Development Specialist, Tim Sanders, shares how to determine the minimum recovery equipment capacity required for extracting a vehicle to a crowd of Iowa Corn Grower Members

Calculating additional rolling resistance

Additional rolling resistance (ARR) is essentially the surface in which the vehicle is stuck or will need to get over in order to become free. Different surface types have different multipliers that, when multiplied by the total vehicle weight, give you the “ARR.”

Keep in mind that these calculations assume the wheels are level with each other.

how to calculate additional rolling resistance by surface type
This chart shows the multipliers for different surface types. Multiply the total weight of the stuck vehicle by the appropriate multiplier to get total “ARR.”

Calculating gradient resistance

Gradient resistance (AGR) is simply the degree of slope that the extraction may take place on. The greater the slope, the higher the multiplier. Again, you will take the total weight of the stuck vehicle and multiply by the appropriate multiplier.

chart for calculating gradient resistance when extracting a stuck vehicle
This chart shows the multipliers for different degrees of slope. Multiply the total weight of the stuck vehicle by the appropriate multiplier to get total “AGR.”

Example Calculation

Let’s say the total weight of the stuck vehicle is 42,000 lbs., and it’s stuck in the snow with a 15-degree slope. Can you figure out the minimum capacity required? Remember the formula is:

Minimum Capacity Required = W + ARR + AGR

See below for the answer.

example calculation of minimum capacity required
Assuming all the factors on the left side of this chart, here is how to calculate the minimum capacity required for extracting a vehicle

Selecting the right recovery straps

Make sure the working load limit of the recovery equipment is greater than the minimum capacity required. Additional resistance could be encountered when the stuck vehicle is deeply submerged, or there is damage to the vehicle that prevents it from moving. When in doubt contact a vehicle recovery expert.

More Vehicle Recovery Resources

If you’re needing to pull an automobile out of snow that’s close to a public roadway, there are specific steps to take to ensure safety beyond just recovery capacity. Click the link above to learn what they are.

We also have resources that cover the common questions our team gets like how to choose a recovery strap and auto-recovery straps vs. tow straps.

If you have further questions on recovery straps and safe vehicle extraction, give Tim or anyone on our team a call at 800-969-6543.

NOTE: This article contains important safety information about the use of synthetic web slings. However, it does not contain all the information you need to know about handling, lifting, and manipulating materials and loads safely. Sling use is only one part of a lifting system and it is your responsibility to consider all risk factors prior to using any rigging device or product. Failure to do this may result in severe injury or death due to sling failure and/or loss of load

Auto Recovery Straps vs. Tow Straps

We get a lot of questions about which straps to use when hauling and towing a vehicle versus the best straps for recovering cars from ditches or other situations. There is a difference between recovery straps and tow straps, and each type has its benefits.

Recovery Straps, Snatch Straps, Tow Straps
Situational usage of recovery straps.

Recovery Straps

Recovery straps are best used to “recover” a stuck vehicle. Say your car or off-road recreational vehicle gets stuck in the mud or a ditch and you’re not going anywhere no matter what you try. If you don’t want to call a tow truck, you can use another vehicle and recovery straps to do the job.

Recovery straps are made of a nylon fabrication that stretches when necessary. These straps, also called “snatch straps” since they can snatch a vehicle out of a sticky situation, have loops on each end.

3x20 strap with looped ends and Cordura eyes
Recovery straps have loops on both ends.

To use a recovery strap you attach the strap to the back of the vehicle performing the recovery at an appropriate frame point, and also to the front of the vehicle being recovered. Thread the strap through the eye of the other end to choke the frame. Make sure the strap is not rubbing against any sharp edges. If you need hardware to secure the strap, anchor shackles are great for recovery vehicles. As the first vehicle begins to move forward, the strap stretches and pulls the stuck vehicle free.

Recovery straps are safer for this type of usage than chain, they’re easier to use and they are not nearly as heavy. Making sure your recovery strap is in good shape is very important before using. Any straps that are frayed or warn increases the likelihood of breakage during a recovery. Straps with faded color are also more apt to break during usage. Store straps out of sunlight and away from excessive heat. Straps perform well in cold temps as well as heat, but should not be used in temperatures in excess of 194 degrees Fahrenheit. To clean your strap, spray with water and do not use chemicals.

Tow Straps

The biggest difference between a tow strap and a recovery strap is the stretchiness of the fabric. A tow strap is made of less-stretchy polyester, and is intended for the towing of a freely-moving vehicle behind another vehicle. Typically, tow straps have metal hooks on each end. Tow straps should not be used in the recovery of stuck vehicles simply because they are less stretchy and can more easily break under the pressure a recovery entails. Traditional tow straps and chains are similar in their towing applications.

Strap Safety

No matter which type of strap you’re using, there are standard safety protocols. Because straps can snap, or break, and launch through the air at a high rate of speed, it’s a good idea to keep any bystanders at least the distance of the length of the strap away from the application.

Choosing the right size strap is also very important. US Cargo Control straps come in widths from 2” to 12” with break strengths from 20,000 lbs. to 400,000+ lbs., and can be made to any custom length since we manufacture them in-house. We can also layer the strap from 1- to 4-ply designs, so you can get the width you want with the strength you need. More plies allow for a narrower strap with greater break strength than single ply.

Our straps are designed with CORDURA® at the eyes of the strap for better resistance to wear and tear. It’s important to note that US Cargo Control straps are manufactured with high-quality, heavy-duty nylon designed for both recovery and towing uses.

If you have any questions about what strap is best for your application, or if you need a custom strap please call us at 866-444-9990 and we’ll be happy to help you get you what you want, when you need it.