When tight is too tight
The slide line itself should never be under tension when the load to be transported is brought to bear on it. Dropping a load into a taut slide line is a sure recipe for an emergency room visit accompanied by a trip to an arborist retailer to replace broken ropes and gear.
If the situation/scenario requires dynamic rigging, or a load that needs to drop a certain distance, a secondary line and rigging system should be used to control and absorb that force, after which the load is attached to the slide line for transport.
The slide line is then put under tension and the load sent along its journey to its intended destination.
There are many ways to tension and loosen the slide line, such as fiddle blocks, tensioning kits with Prusik minding pulleys, or a device such as the Good Rigging Control System, all of which can be fairly user-friendly. Using trucks, skid steers or ATVs to tension slide lines is a very poor choice, as it can easily result in broken gear, trees and even climbers or crewmembers.
Control is key
Except for extremely small or light loads, some form of control line should be employed to control the speed of “sliding” on descent; without one, even loads that are thought to be extremely small or light will appear to be traveling fairly rapidly to the crew at the receiving end. In addition, loads “sliding” down without any control line will increase the heat input on the slide line, perhaps making the melting point an even more important consideration. When properly set up, the control line need not involve any additional rigging, and can simply be the rope that was used to “catch” the dynamic load prior to the slide line being tensioned.
Consideration also should be given to the manner in which the control line will be “controlled,” as relying on a crewmember’s grip strength when sliding a 250-pound log toward the brand-new chipper may be a poor choice. A Port-A-Wrap or other friction management device might be a better option.
Traveling and carrying
A traveler or carriage is the item to which the load is attached, which “slides” down the line to its final destination. Many pieces of arborist gear can be used in this application, but with a wide variety of performance levels.
The simplest carriage might be some form of carabiner or snap, but users should keep in mind that the friction generated will not only slow the load’s travel but create a great deal of heat input in the slide line. Any number of pulleys are available, from single to multiple sheaves that will travel quite smoothly and generate less friction, but users should evaluate any pulley used for the necessary strength and appropriate design for the load involved.
Having multiple travelers or carriages on hand not only will assist in moving larger or longer loads, but will make the process more efficient as the climber can prepare the next shipment while the previous one is being removed from the slide line.
Slide lines aren’t required in every situation, but, when used appropriately, they can save a great deal of time, energy and money. Once added to an arborist’s mental toolbox, they can make seemingly endless brush hauls slip and slide away.
(Courtesy of Tree Services Magazine: http://www.treeservicesmagazine.com)