The off-road recovery industry has grown exponentially over the last decade, especially with the introduction of synthetic lines and lower cost winches. You can essentially outfit the front of your rig with 8k of stump-ripping, mall-parking lot recovery power for a measly $249.99, and thats before a sale! I’m not at all against this - I think its awesome. Its enabling a whole new level of people being able to afford and utilize winching systems. I am against the lack of knowledge associated with winching systems and associated equipment.. Along with the cheap winch comes cheap gear. Cheap cable. Cheap shackles. Cheap blocks. Cheap rigging. This creates trouble.
In most cases, when the $249.99 winch fails - it just stops working. The motor fails to operate. Your stuck.No problem, call - complain - gripe - replace. When a winching accessory breaks - it can seriously harm you. It can kill you. Before we go any further into this, we need to cover some basic recovery, terminology, and algebra.
There are several common recoveries performed with a winch. There are also several misunderstood ideas about a winch. Outlined below is not all-encompassing. Should you feel the need to learn more about recovery or winch safety, feel free to enroll into one of our classes.
The recovery gear we should use is similar to the webbing, straps, and ropes the logging and lifting industry has been using for years. For our safety, we need to think about terms like minimum breaking strength or working load limit.
MBS or Minimum Breaking Strength: A common term in relation to synthetic rope, straps, and most recovery equipment. Effectively the MBS is equal to the WLL x Safety Factor, though it is not a common theme to see a WLL or safety factor released with synthetic rope or straps.
WLL or Working Load Limit: A term often used with the rigging industry, where a safety factor is often taken into account. A safety factor of 4:1 means that the equipment is safely rated to 4 times the posted WLL. We commonly see shackles with a WLL of 4.75T (9500lbs) and a safety factor of 4:1. That means that the shackle could have a 9500 pounds of pressure applied to it indefinitely with no ill effects. As soon as you go over that weight it starts fatiguing the shackle. If you continually add pressure to the shackle, up until you reach the 4:1 safety factor, the shackle will hold. As soon as you reach 38,000 pounds of pressure the shackle will yield and destruction will occur. An item that has been used over the WLL should be discarded.
The power of a winch is directly related to the number of wraps the winch has on the drum. An 8,000 lb winch will only pull 8,000 pounds on the first wrap. Because of the need to leave a minimum of 5 wraps of your rope on the winch for friction to hold it securely while under load - the first roll of rope pulling at a maximum 8,000 pounds will be shorter than the remaining wraps. Different manufacturers have different ratings, depending on the size of the winch, line, etc. Check with yours.
A direct (single line) pull - The vehicle is attached to an anchor via the winch rope. The winch is powered in, applying no more than the maximum force of the winch to your anchor.
A redirected (single line) pull - Utilizes a pulley block connected to an anchor to redirect your winch rope to another anchor or object. Normally used when extracting another vehicle.
A double line pull - Utilizes a pulley block connected to an anchor. The rope from your winch is put through the pulley block and then attached back to your vehicle.
In both a direct or redirected pull situation, the maximum amount of force applied is determined by your winch. With an 8,000 lb winch your maximum amount of force applied will be around 8,000 pounds. With a 10,000 lb winch your maximum amount of force applied will be around 10,000 pounds.
With a double line pull, in laymans terms - you are essentially doubling the power of the winch and decreasing your pulling speed by ½. An 8,000 lb winch will have the capability of pulling up to 16,000 pounds.
Now that we have the basics, lets pick apart a recovery kit. This one belongs to a fairly large company, though I will leave their name out of this.
20,000 lbs. (9072 kg) maximum capacity snatch block, with grease port.
2" x 8' (5cm x 2.4m) tree trunk protector, rated to 14,400 lbs. (6531 kg).
2" x 30' (5cm x 9.1m) standard recovery strap, rated to 14,400 lbs. (6531 kg).
3/4" (20mm) D-shackles (2x).
*Kit sold to work with winches up to 10,000 lbs.*
The first thing I notice is no WLL, Safety factor, or MBS. Are the straps rated for 14,400 lbs in a basket, choker, or 'vertical' position? We don’t know if the straps are rated at 14,400 lbs indefinitely or if they will only take that much weight once and break. If we apply 14,401 lbs, are we risking death? When performing a recovery, ALWAYS err on the side of caution. I say yes, the instant we go over that rating we are endangering EVERYONE involved.
Now, lets use this kit with our recovery scenarios assuming the shackles are typical 4.75T WLL, the remaining posted ratings are MBS, the straps are posted a 'basket' rating, and that we are mired to the fenders so we are going to use every ounce of pulling power our little winch will give us.
It will clearly pass when used in the direct and indirect pull scenarios.
It fails when used in a double line pull at maximum pull. This brings up the question of when you’ll be at maximum pull? I’ve strained a winch to the point where it flat out quit on the first wrap with a double line pull on two occasions in my entire life - one was life threatening, the other merely caused by the idiocy of others and myself trying to be a good person. Both situations turned out with a positive note. On both occasions I used my hand picked recovery gear. We will pick through that at a later time.