In recent years, compact, lightweight pulleys have been used in tree care, tower work, construction, technical rescue, and a host of other applications. As you can see over the years, a variety of different designs and features have been developed, but for technical rescuers who have to rig life safety loads, the openable swivel pulley has become a very important tool. These features help rescuers quickly set up and operate rope systems to rescue people in difficult-to-reach locations. Now let’s go to Keith Lesinski in the Petzl Technical Institute to talk about the technical specifications of the spin pulleys.
Thanks, Steve. The Spin line of pulleys contains three models. The L1, the L2, and the L1D. The Spin lineup brings two innovative new features to the Petzl pulley line. First, the Spin pulleys contain an integrated swivel, which allows the pulleys to orient correctly under load. The main attachment point is forged aluminum with a smooth cross-section. This makes the attachment point compatible with carabiners, but also ropes and slings. The moving side plate is openable while the pulley is connected to the anchor. This allows you to install a rope without having to disconnect the pulley from the anchor. This makes the pulley not only easy to use but also reduces the chance of dropped objects while working from height. The moving side plate is secured with this triple-action mechanism. It can be operated one-handed. The mechanism also has this red indicator to alert you when the side plate is not fully closed.
The Spin L1 and L 2 are compatible with a rope diameter range of 7 to 13 millimeters in diameter or up to half-inch diameter. The pulley sheave is 95% efficient and both the L1 and L2 have a working load limit of 8 kilonewtons. That means for the Spin L1, each strand has an allowable load of 4 kilonewtons. The L2 also has a working load limit of 8 kilonewtons.
This means an allowable load of up to 2 kilonewtons per strand. One of the great things about the L2, is that we specifically allow it to be used with just a single sheave in use. In this orientation, the spin L2 as a working load limit of 6 kilonewtons or 3 kilonewtons per strand. Because the entire Spin lineup is NFPA G rated, they all have a minimum breaking strength of 36 kilonewtons. Likewise, the Spin L2 has a becket strength of 22 kilonewtons. One of the cool design features of the Spin L2 is that both side plates have the same geometry. Notice that the locking switch is on the upper left-hand side on both side plates. This means you use the same hand motion to open both side plates of the spin L two.
Now let’s talk about the spin L1D. On the outside, the Spin L1D looks really similar to the L1. It has an integrated swivel and an openable side plate. On the inside, that’s when things get different. The Spin L1D is equipped with a faceted sheave, similar to the Petzl Maestro. The sheave is also mounted on a one-directional pulley wheel with these arrows indicating the direction of travel. These two features of the sheave mean the Spin L1D is uniquely designed to be compatible with a descent control device. Because the sheave rotates in only one direction, the L1D provides high efficiency while hauling exceptional, yet exceptional control while lowering. An excellent application for the L1D would be as a high point redirect in hauling and lowering applications.
The compatible rope diameter range of the L1D is 8 to 13 millimeters in diameter. As with the other Spin pulley, the L1D is an NFPA G rated with a minimum breaking strength of 36 kilonewtons. The allowable working load limit of the L1D is 6 kilonewtons or 3 kilonewtons per strand. The sheave is 93% efficient, which you’ll notice is a little bit lower than the 95% efficiency of the L1. This is due to the internal mechanism of the one-directional pulley wheel. Note that that 93% efficiency rating is a real-world measurement, but taken with an 8-millimeter rope at the smallest diameter range of the L1D. If you’re using a larger diameter rope, you will notice a slightly decreased efficiency. So how do these numbers play out in the real world? Well, if you’re hauling a 100-kilogram load, that means your haul system will need to impart about a hundred kilograms of force to be able to lift that 100-kilogram load.
While lowering, the faceted sheave stops rotating, and the facets apply friction to the rope system. In a 90 degree redirect as a high point anchor, the L1D acts as about a 50% efficiency pulley. This means for our 100-kilogram load context, our descent control device, and our anchor only experiences about 50 kilograms of tension. For reference using a 90 degree redirect through the Petzl Am’D H frame carabiner acts as about a 70% efficiency turnaround point. That means with a 90 year redirect through the Am’D carabiner, we would have a 70-kilogram load while lowering the 100-kilogram load. Note that the Spin L1D doesn’t increase the upper range of the working load limit of your hauling, lowering, or belay devices. While hauling, for example, your progress capture device will still experience the full load of the system. It’s only when you transition to lowering that your descender experiences a reduced load. The L1D just provides greater comfort and control while working within the acceptable ranges of your devices.
Peace on your Days