How to use the force of friction to your advantage in tree climbing operations.
The force of friction plays a major role in almost every aspect of tree care professionals’ daily work activities. All of the hitches and knots that are so vital to climbing arborists for attaching or securing themselves and other objects to lines and cordage rely on some degree of friction to stay tied in place. Friction works to a tree crew’s advantage when carrying out rigging operations when they use the friction generated by a lowering device or tree wraps to lower wood and branches under control. Yet, a similar form of friction to the one that allows these experts to lower huge loads safely and securely can be inefficient when attempting to ascend into the tree.
This would be friction present at the tie-in point (TIP). Conventional and traditional climbing involves simply running the climbing line over a branch or around the trunk in the desired location for the TIP; and though this practice may seem to be simple and easy, the friction generated by the rope on bark/wood contact takes quite a toll on the user, the climbing line and the tree. There are a variety of commercially available friction-reduction devices that can be used to better manage this friction at the TIP, and also a myriad of ways that climbing arborists can create their own out of appropriately rated slings, carabiners and pulleys once they understand the advantages of reduced friction aloft.
The cambium saver is simply a sewn leather tube shaped in a curve. The climbing line passes through it, reducing the amount of friction the climber has to work against while also protecting both rope and bark from excessive wear and heat due to mutual contact. Once the desired TIP is attained with the throwline, the end of the climbing line, with the cambium saver already installed on it, is pulled up into the TIP. A slipknot beneath the device keeps it in place on the rope and allows the user to release it from the ground, installing the cambium saver over or around the desired TIP. Removal is easily accomplished by tying an overhand knot in the climbing line, pulling it up to the device and simply pulling it out to remove it.
The friction saver, manufactured by Buckingham Manufacturing, consists of a large and small ring at opposite ends of a webbing strap. The climber’s rope passes through the rings after installation, reducing friction while still protecting the tree and rope from contact with each other. The installation of a small Prusik cord on the device also allows it to be used in a choking fashion when spur climbing or when no branch attachment point is present at the desired TIP, though the choking feature cannot be installed from the ground.
This device, developed and manufactured by Advanced Ropeclimbing Technology (ART), employs both a camming system to allow it to be choked against the tree or let out to the desired length, and a smooth and fluid pulley that the climbing line passes through. The design of the device prevents excessive contact between rope and tree. Although the rope guide can be installed from the ground with some imagination, it is not as simple a process as some of the other devices discussed here; and is most commonly carried aloft while footlocking to be installed by hand once the desired TIP has been reached. The device can be removed from the ground either by a second line installed when aloft or through the use of a Double Snapper, also from ART, for remote retrieval.
A rope guide installed at the desired TIP with the climbing line running over the smooth pulley. Photo: Michael (House) Tain
The fimblSAVER by Teufelberger is a ring-and-ring friction saver with a 17-cm-wide surface to help prevent damage to tree bark. The two stainless steel thimbles allow the climbing rope to run smoothly during canopy work. The 10-cm-long and tapering longitudinal seam makes it easy for the user to pull the cambium saver off. The fimblSAVER can be set and retrieved from the ground and includes a retrieval ball.
BuckBlocks or MagBloc
BuckBlocks, also from Buckingham Manufacturing, provide the capability to climb out of an actual block at the TIP, improving the rope’s bend radius and reducing friction immensely, while still being easily installed and removed from the ground through the use of a throwline. The rope, once installed, runs through a rope channel across the two rotating sheaves, while the separate halves of the device are held securely together by rare earth magnets. The amount of friction reduction, due to the two rotating sheaves, is greater than either the cambium or friction saver, while still protecting both the tree and rope from contact and associated wear.
Climbing arborists who wish to create their own friction management device rather than purchase one are only limited by their imagination, and the always important breaking strength standards for personal support. Any variety of straps, slings, spliced-rope tools, connecting links and pulleys can be combined to reduce friction at the TIP; and with some time or thought, allow for easy installation and retrieval from the ground.
Managing friction effectively at the TIP will not only help climbing arborists work more safely and efficiently, but also increase the lifespan of their ropes while reducing heat and friction damage to the trees they are there to care for. Although this brief introduction cannot fully encompass the various advantages and disadvantages of specific friction management devices, it does provide a glimpse into the possibilities and an introduction to their use.
(Courtesy of Tree Services Magazine: http://www.treeservicesmagazine.com)