Any time you can reduce the potential kinetic energy in a winch system it is a Good Thing. PKE, as we’ll call it, comprises any part of the system that could become a projectile in the event of a failure of itself or any other component. In the vast majority of winch mishaps it’s the line that breaks, but shackles, shackle mounts, tree straps, even entire bumpers are unlikely but potential sources of high-velocity widow-making destruction.
The advent of synthetic winch line reduced the risks inherent in winch recovery by an order of magnitude. Although they both display about the same amount of stetch under load (less than one percent), synthetic winch line—typically SK-75 Dyneema—weighs one seventh of the same length and load-rated steel cable, and its 12-strand woven construction prevents the violent untwisting motion that occurs when a steel cable breaks. (For much more on steel versus synthetic winch line, see here.)
Recently, several companies have introduced soft shackles made from material identical to synthetic winch line. Soft shackles lock via a deceptively simple-looking turks’ head knot on one end and a spliced loop on the other—no threaded pin, in fact no metal at all. As with Dyneema winch line, the mass of the part is hugely reduced, along with its PKE. (Report soon.)
One frequently used winch accessory, however, stubbornly retains its mass: the pulley block, or snatch block, used to construct a redirected pull or increase the pulling power of the winch. Since the pulley itself must be of significant diameter to avoid damaging the line, the cheek blocks that support it must also be large and stout, and the axle of sufficient diameter to ensure a suitable working load limit (WLL) with a substantial safety margin. As a result, for example, even ARB’s excellent “Ultra Lite” winch pulley weighs 5.3 pounds, and their standard pulley is close to eight pounds.
That’s now changed—at least somewhat—with Research In Recovery’s aluminum Recovery Blok (sic). At four pounds even, the RIR pulley boasts a 25 percent reduction in mass over ARB’s lightest model.
To be honest, that 1.3-pound savings represents less of a safety enhancement than a simple reduction in handling weight. If you’re ever unspooled 75 feet of steel winch cable up a hill while carrying several steel shackles, a tree strap, and a standard steel pulley block you’ll appreciate this. Still, if the worst happens and you find a winch pulley headed toward you at 40 feet per second or so, better it weighs four pounds than five and a quarter . . .
Since such accidents in a properly set up and monitored winch system are vanishingly rare, let’s look at the RIR pulley from a practical point of view, first giving due credit to the welcome lightness. Next up of note is the very fine production quality. The body of the pulley is beautifully machined billet 6061 aluminum, given an attractive tumbled finish. All the edges are rounded, and shallow raised ridges protect the ends of the stainless-steel axle, which is secured with external snap rings for ease of maintenance and cleaning. The polymer pulley is smooth and spins easily; its semi-circular groove is 1/2-inch wide, thus suitable for most winch lines.
The cheek blocks are finely finished exactly flush with the edge of the pulley; this is attractive but, as Camel Trophy veteran Duncan Barbour pointed out when I showed it to him, would fail to protect the line from abrasion if the pulley wound up vertically in contact with the ground or a rock with line being pulled through it. The ARB Ultra Lite pulley incorporates shoulders on the flanks of the pulley which would help prevent this. If the Recovery Blok’s cheek blocks extended even a quarter inch there would be enough stand-off space to provide some protection.
Of more potential hassle is the securing hole at the head of the unit. It is sized so that only the pin of a shackle will fit through it, not the loop. Thus, for example, if you wanted to attach the pulley to a typical winch bumper, the shackle mounts of which also only take the pin of the shackle, you’d need to insert a second shackle, loop to loop, to connect the RIR pulley—thus negating all your reduction in PKE and handling weight. This wouldn’t be a factor if, say, you’re rigging a redirected pull off a tree using a tree saver strap. The loop of the shackle will fit through the loops in the strap, and the pin can then secure the pulley. (A soft shackle fits as well.)
Last to consider, but far from the least important, is the working load limit and breaking strength. WLL of the Recovery Blok is 20,000 pounds, identical to that of the ARB Ultra Lite unit (and superior to their standard pulley), and suitable for winches in the 9,000 to 12,000-pound range.
Unfortunately—critically, in fact—Research in Recovery does not yet know the breaking strength of the Recovery Blok. ARB lists the breaking strength of the Ultra Lite pulley at 38,500 pounds—nearly a two-to-one safety margin. While it’s possible the RIR pulley will exhibit a similar margin once it is tested (the company says they should have the information by the end of the year), without a solid figure it would be foolish to assume it is anything above the WLL, and that is insufficient for a piece of equipment that will be employed in potentially hazardous situations. Despite the high quality of the RIR pulley and its welcome weight savings, until I see a documented safety factor I can’t recommend it. I’ll update here if I learn more.
RIR is here.