How to Extract a Stuck Vehicle
To properly extract a stuck vehicle using recovery equipment, there are a couple important calculations you should make in order to make the recovery safe and simple. Whether you are needing to get a vehicle unstuck from the mud, sand, gravel, or snow, this formula covers all terrain types.
How to calculate minimum recovery capacity for vehicles stuck in mud, sand, gravel, or snow
To ensure you’re using the proper recovery equipment, you need to determine total vehicle weight (W), additional rolling resistance (ARR), and additional gradient resistance (AGR). These are quite simple to determine and won’t take much time at all.
Minimum Capacity Required = W + ARR + AGR
- What is the weight of the stuck vehicle?
Make sure you factor in all cargo, attachments, and trailers. This is the “W” part of the formula.
- What other factors will affect how hard/easy it is to extract the vehicle?
By “other factors” we’re mainly talking about two things: additional rolling resistance (ARR) and additional gradient resistance (AGR)
How to calculate additional rolling resistance (ARR)
ARR is a measure of the surface resistance that the vehicle is stuck in or will need to get over in order to become free. Different surface types have different multipliers, as shown in the diagrams. Multiply the proper number by the total vehicle weight to get “ARR.”
Note: These multipliers assume the wheels are level with each other.
Multiply the total weight of the stuck vehicle by the appropriate surface multiplier to get total rolling resistance (ARR).
How to calculate gradient resistance (AGR)
AGR is a measure of the degree of slope (if any) that the stuck vehicle is on. The greater the slope, the higher the multiplier. Again, take the total weight of the stuck vehicle and multiply by the appropriate multiplier.
If the stuck vehicle is on a slope, multiply the total weight of the stuck vehicle by the appropriate multiplier above to get total “AGR.”
Vehicle Recovery Calculation Example
If you have a stuck vehicle that’s 42,000 lbs., and it’s stuck in the snow on a 15-degree slope, what would the minimum recovery capacity need to be?
Again, the formula is:
W + ARR + AGR = Minimum Capacity Required
Example of how to calculate the minimum recovery capacity needed to safely extract a stuck vehicle.
Use the Right Recovery Straps
Now that you know the minimum capacity required, you can be confident in which size recovery strap to use and should get the vehicle out in no time at all.
If you’re looking for more information on recovery straps and vehicle recovery and towing, see our blog post on how to choose a recovery strap and learn the difference between auto-recovery straps vs. tow straps.
NOTE: This guide 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