Smart off roaders have known for years that the most secure way to use your recovery winch is replace the hook with a common screw pin shackle. Unless you are competing, the added seconds required to use a shackle versus a hook during a vehicle recovery is not worth the safety risk associated with standard winch hooks.
The technical name for a standard winch hook is " Clevis Slip Hook". This describes two things. First, clevis refers to the method of cable attachment - the cable eye is attached to the hook by a clevis pin and cotter pin. Second, "slip" refers to the size of the chain link that can be slipped through the hook opening. Most winches are equipped with 3/8 clevis slip hooks. This means that the hook is designed specifically to work with chains that have 3/8 thick chain links. Unless you are using chains in your recovery, this is not the right piece of hardware to have on the end of your winch cable. At Factor 55 we are still puzzled as to why winch manufacturers continue to sell winches equipped with hooks designed for chain links when off roaders have been using synthetic recovery straps for over two decades now.
In addition, most 3/8 clevis slip hooks have a safe working load limit of 4000-7000 pounds. The average 8K winch exceeds the working load limit of these weak hooks regularly. Of course the safety factor built into the hook is 3-4X, but it is still not wise to exceed any working load limit of any hardware. In contrary, the standard ¾ screw pin shackle has a working load limit (WLL) of 9500 pounds, and a safety factor of 5-6X. Most screw pin shackles have an ultimate breaking strength of 50,000 to 60,000 pounds.
The cross section of the standard hook is airfoil shaped to prevent chain links from slipping, and not ideal for synthetic strap fibers. This shape causes high fiber stresses that reduce the rating of the recovery strap. Hooks equipped with safety latches pose other hazards as well. Many safety latches are simply bent sheet metal parts with sharp edges and springs. This is not a concern with chains, but a potential cutting hazard for recovery straps. The safety latches cannot bear any loads as well.
The hook opening of the standard winch hook is too small to safely attach two ends of a common recovery strap so most off roaders use a screw pin shackle to hold the strap anyways.
Standard winch hooks do not stow neatly against either Hawse or roller fairleads. They were not designed to do this. That is why it is common to see winch cables extended and hooks attached to bumpers, tow hooks, undercarriage parts etc.. It is not recommended to leave the winch cable or synthetic rope pulling at a right angle to your fairlead simply to attach the hook to something convenient – this can permanently weaken the fibers right at the fairlead surface.
Anytime a hook is used, there is a chance that whatever you put into the hook opening can escape. This is especially important in vehicle recovery where the winch cable is cycling in a loaded and unloaded condition regularly as the towing vehicle or towed vehicle lurches forward. In contrary, the standard screw pin shackle is a completely contained link where strap ends have no way of escaping even during tight/loose cycles.
Factor 55 products are designed and manufactured using state of the art technologies. All of our products are designed using SolidWorks CAD systems and stress analyzed using COSMOS Finite Element Simulation software. The FEA results allow us to optimize a design concept by adding or removing material or changing material properties where necessary.We then validate our theoretical results by instrumenting and destructively testing prototypes of all of our product designs. This is conducted at a test and measurement facility that is also certified for National Defense Department rigging and hoist testing.
Most of the products are manufactured right here in Idaho within a 10 mile radius. Both the ProLink and Winch Lock bolts are manufactured from CNC machined billet material – no cheap castings or forgings for us.
At Factor 55 we don't believe in engineering compromises. That's why we produce all of our products from aerospace quality materials. From 6000 and 7000 series aluminums, to 6AL-4V titanium double shear pins, we strive to offer you the very best designs made from the very best materials.
FEA or Finite Element Analysis, is a mathematical method of determining stresses in materials before actually building a physical prototype. This allows our engineers to optimize our product designs for the greatest strength to weight considerations. In other words, we can remove material where it is not needed and add material to any weak zones of a particular design concept. This method of design takes away the guess work on determining how thick or what material something should be made of.
One of the images to the right shows our winch locking bolt being subjected to over tightening of 40 ft-lbs of torque. The colorful display depicts the stress distribution with the highest stress shown in red. In this case, as expected, the highest load is in the shank of the bolt near the minor thread diameters. All of the distortions are magnified to better see how the product will behave.
At Factor 55, all of our designs are optimized with Cosmos FEA by a licensed professional engineer registered in the State of Idaho, and later, prototypes are destructively tested for validation. This allows us to provide you the best designed, efficient, and cost effective products for your vehicle.