By Michael Tain
The profit mentioned in the title of this piece should not be confused with Scott Prophett, who, along with Norm Hall, designed and developed the Port-a-wrap, a lowering device discussed here. Additionally, it should be realized and understood that lowering devices are not only for fun and profit, but also for safety and efficiency — and often these all go hand in hand.
The traditional method of taking “wraps” around the trunk of a tree — more “wraps” creating more friction –> to control the descent of the piece is still important for tree care professionals to know and understand in the event of a missing or back-at-the-shop lowering device. But it is not nearly as safe, efficient, or fun as using an actual lowering device.
The need to lower pieces of a tree or trees under control is probably as old as tree care itself. Tree crews are more often than not confronted with a wide variety of targets of opportunity beneath their work while aloft. The target may be as obvious and benign as the putting-green-quality turf to which the homeowner will accept no damage, or as complex and hazardous as an electrical transmission line. Either target — for safety, efficiency and profitability — demands the ability to control the descent of the load securely and smoothly.
An additional concern when controlling the descent of tops, branches or pieces of trees is how much shock load or what forces are being introduced into the tree itself through the use of the lowering system. Bringing a load to an immediate and abrupt stop, or “snubbing it off” exponentially and dramatically increases the forces at the rigging point — typically near where the climbing arborist is located often in amounts equal to ten times or more of the weight of the load.
Although experienced ground personnel will learn over time how many “wraps” around a tree are needed for a particular load. The fear of losing control of the load is typically greater, resulting in too many “wraps” and a load brought to a sudden and abrupt stop with resulting excessive forces at the rigging point. Conversely, the application of too few wraps could result in the piece descending at a high rate of speed toward the target; and ground crew members who neglect to let go of the rope, they may find themselves entered in the soon-to-be-Olympic-sport of lawn skiing. “Tree wraps” also are not the most efficient of lowering methods, as the rigging line is continually being walked around the trunk to generate friction or “unwrapped” to release it. The wear and abrasion taking place on the rope can also be a reason for concern as the rope continually rubs back and forth against the bark to generate the required friction — possibly causing damage to the tree’s cambium layer in rigging operations where the tree is not being removed.
Lowering devices provide modern progressive tree care professionals with an option that is fairly easily installed, fully portable, quickly learned, and offers the same amount of friction regardless of which species of tree it is installed. These factors will increase the amount of consistent control ground personnel will be able to have over descending pieces, and consequently increase safety and efficiency. Additionally, all the lowering devices discussed here are either capable of lifting loads as well as lowering them, or are capable of it with the assistance of other components.
A Port-a-wrap III in place on a tree in the non-loaded position. Note the eye sling girth hitched around the larger “U-shaped” section for attachment. — Photos courtesy of Michael Tain.This device, mentioned previously, is one of the simplest lowering devices available, is easily moved from tree to tree throughout the worksite, and is also very safe and efficient. The Port-a-wrap comes in a variety of sizes and materials, and has a safe working load of 1,000 to 2,000 pounds (depending on the model). Friction is generated by taking turns around the barrel of the device — more turns generating more friction. The device itself is attached to the tree by an eye or whoopie sling. A bight of the lowering line should be passed through the small “U-shaped” opening on the upper side of the Port-a-wrap and underneath the pin on the bottom of the barrel. The running end of the rope than makes the desired number of turns around the barrel. The design of this device also allows the operator to control the line easily — if the appropriate number of wraps have been applied — from a safe distance so as to avoid being beneath the load being controlled. The eye or whoopie sling should be girth hitched to the large “U-shaped” opening on the bottom side of the barrel. This girth hitching will provide a secure attachment while also eliminating the need for a connecting link, which might very well be cross loaded during dynamic rigging operations and fail. The Port-a-wrap is primarily designed and intended as a lowering device, but the addition of some form of mechanical advantage system, such as fiddle blocks, will allow it to lift or pull loads as well. Operators wishing to use it in this application would be well served to use a redirect block at the base of the tree, set the Port-a-wrap on an adjacent tree, and use the fiddle blocks or other mechanical advantage system on the horizontal section of line thus presented. This will eliminate the difficulty quite often experienced by attempting to work, advance, and release the fiddle blocks in a vertical orientation — often right beneath the load being controlled.
Good Rigging Control System (GRCS)
A GRCS in place on a tree with rigging line already tensioned on the winch prior to lifting.This device — also developed by a working arborist, Greg Good — is more complex and much heavier than the Port-a-wrap but has several features and abilities that make it an excellent choice for tree care rigging operations. Although it can be installed on a tree by one person of reasonable strength and dexterity, it is much easier accomplished by more personnel. The GRCS is secured to the tree with a heavy-duty ratcheting strap; and for additional security during large loads and removals, is available with a visor plate that locks it into the kerf of a shallow horizontal chain saw cut made into the tree. It comes with both an aluminum drum for straightforward lowering and a Harken two-speed winch for lifting/pulling. These two units are easily removed and switched by sliding them in and out of the mounting bracket attached to the tree, though users should pay attention to the clearance beneath the mounting bracket when attaching it to the tree if they are aware they will be switching applications. The winch is capable of two “speeds,” 44-1 when the handle is turned in one direction, and 22-1 when turned in the other. Obviously the 44-1 ratio will ease the operator’s exertion when turning the handle, but lift/pull the load more slowly, while the opposite occurs when using the 22-1 ratio. The device has a safe lifting capacity of 3,000 pounds, and with a suitable rigging point can easily function as an inexpensive portable crane. Its integral fairleads and self-tailing ability also make the GRCS very easy for one person to operate. For non-removal rigging operations the GRCS is equipped with rubber pads to minimize damage to the tree. An additional feature is the availability of a winch driver for 1/2-inch gas-powered drills (for multiple lifts where turning the handle that much might become overwhelming for ground personnel).
H2 Hobbs lowering device
The H2, an upgraded and redesigned version of the Hobbs Lowering Device, was designed and developed by tree care legend and rigging pioneer Ed Hobbs. This device features lifting, pulling and lowering capabilities all readily available in one unit with no modification or
The earlier version of the Hobbs (not the H2 discussed in this article) in place with the rigging line tied off on a tree with additional padding provided by a pair of chaps.additional equipment required. The device can be mounted in three ways, and uses a heavy-duty ratcheting strap. Preservation mode is for pruning and minimizes impact on the tree, standard removal mode places three spiked “feet” into the trunk, and “cut-in” mode actually places the device directly into the wood of the tree for extreme loads/lifts. Lowering operations take place on the same alloy bollard or drum on which lifting/pulling operations occur, and the alloy dissipates heat well. Lifting or pulling power is generated by using a breaker bar to turn the ratcheted drum with the rope wrapped around it, thereby advancing the line. Fairleads assist in routing the rigging line onto the drum correctly, and instructions/guidelines are printed on the body of the device itself to help assure proper use.
All of these lowering devices have more features, abilities and even challenges than were able to be discussed here, but this information does open the door to considering the possibility that there might be an easier and safer way to get that wood on the ground than walking around and around that tree. So why not explore the safety, efficiency, profitability, and, yes, fun of lowering devices?
Michael (House) Tain is a contract climber, splicer, educator and writer associated with North American Training Solutions www.northamericantrainingsolutions.com and Arbor Canada Training and Education www.arborcanada.com He is currently located in Lancaster, Ky., and can be reached via e-mail at firstname.lastname@example.org