Choosing a Lowering Device for Tree Work

What a lowering device for tree work does

A lowering device for tree work is a friction device mounted at the base of the tree or on a nearby anchor. The rigging line runs from the load, up through a block or crotch in the tree, and down to the device, where it takes a number of wraps around a drum or post. The friction from those wraps lets one person on the ground hold, run and stop heavy pieces with a manageable amount of tail tension.

Without a lowering device, the ground worker is relying on gloves, a tree trunk and luck. With one, they can let a piece run, slow it, and stop it where it needs to land. It protects the groundie's hands, reduces wear on the rope and gives the crew far more control over where wood ends up.

Tree limb lowering devices range from a simple aluminum post to trunk-mounted capstans with built-in winches. The right choice depends on how heavy your rigging is and whether you also need to lift and tension.

Port-a-Wrap: the simple friction device

The Port-a-Wrap is the classic friction lowering device: a post with horns that you attach to the trunk with a sling, chain or strap. You add friction by taking more wraps and control the load with tail tension. It is light, inexpensive and easy to learn, and it handles a large share of residential rigging.

Buckingham makes them in several sizes. The Port-A-Wrap Mini suits light rigging, the medium Portawrap is the everyday size for many crews, and the large model takes bigger rope and heavier loads. Kits like the Port-a-Wrap with a whoopie sling give you the device and an anchor sling together.

The main limitation is that a Port-a-Wrap is for lowering only. Adding or removing wraps under load is awkward, so set the number of wraps for the expected load before the cut.

Hobbs H2: lowering and lifting

The Hobbs H2 is a trunk-mounted lowering device with a drum that you take wraps around, like a Port-a-Wrap, but with a mechanism that lets the operator take in rope as well as let it out. Hobbs markets it as a lowering and lifting device, so crews use it to take up slack, pre-tension a rigging line and make small lifts.

It costs considerably more than a Port-a-Wrap and is heavier to carry, but it gives a level of control that many removal crews find worth it on heavy rigging jobs. Follow the maker's manual for rope size, number of wraps and working limits.

GRCS and other winch-equipped devices

The Good Rigging Control System (GRCS) is a trunk-mounted capstan with a built-in winch, strapped to the tree. Crews use it to lower heavy pieces, lift loads, tension lines and pull trees over. It is one of the most capable tree rigging systems you can put on a trunk and one of the most expensive.

The Stein RCW 3001 is another heavy-duty trunk-mounted option, with an add-on winch kit. CMI's LCD and the Jail Brake are friction devices built for controlled lowering. For light rigging, a rigging rope wrench uses friction in a compact device, but stay within the load marked on it.

If you rig large wood every week, a winch-equipped device pays for itself in time and control. If most of your rigging is small to medium limbs, a Port-a-Wrap or similar friction device is plenty.

Bull rope and rigging rope

The rigging line, often called a bull rope, carries the load. Most arborists use a double-braid polyester rigging rope for its strength and low stretch. Popular choices include Samson Stable Braid, Samson Arbor-Plex, Teufelberger Sirius bull rope and Husky bull rope, in diameters such as 1/2, 5/8 and 3/4 inch.

Match the rope to your lowering device, block and slings. Every device has a rope diameter range, and running rope outside it can mean too little friction or too much heat and wear. Shock loads from a dropped piece can be many times the piece's weight, so plan rigging loads with a generous design factor, inspect rope before every job, and retire rope that is glazed, cut, or has been badly shock-loaded. See our rigging rope section for options.

Slings, blocks and the rest of the system

A lowering device is only one part of the rigging system. At the top, a rigging block on a sling gives the line a smooth, rated redirect instead of grinding over a natural crotch. At the bottom, an anchor sling attaches the device to the trunk. Every connection in between needs to be rated for the load.

Adjustable whoopie slings, dead-eye slings and ring slings are the common choices. Our rigging slings and rigging blocks sections cover the main types. The system is only as strong as its weakest component.

Matching a lowering device to your work

Think about the heaviest pieces you rig regularly, not the occasional giant, and the size of rope your crew already uses. Then decide whether you need lifting and tensioning or lowering alone.

• Light pruning and small removals: Port-a-Wrap Mini or a rigging rope wrench
• Everyday residential removals: medium or large Port-a-Wrap with an anchor sling
• Heavy rigging with lifting or pre-tension: Hobbs H2
• Heavy rigging, lifting, tensioning and pulling: GRCS or a similar winch-equipped device

Training, communication and inspection

Rigging puts large forces on people, trees and equipment. Learn it from a qualified trainer, and follow ANSI Z133, the manufacturer's instructions and your company's procedures. Agree on clear signals between the climber and the ground before any piece is cut.

Keep hands well clear of the wraps and the drum, wear gloves, and stand where a running line cannot catch you. Inspect the device, slings and rope before each job, and retire anything cracked, deformed or excessively worn.

Common questions

What is a Port-a-Wrap?

A friction lowering device attached to the base of a tree. The rigging line takes wraps around it, and the ground worker controls the load with tail tension.

What is the difference between a Port-a-Wrap and a GRCS?

A Port-a-Wrap lowers loads only. The GRCS adds a capstan winch, so it can also lift, tension and pull, but it costs much more and weighs more.

What size bull rope should I use with a lowering device?

Use a rope within the diameter range the device maker specifies, and rated for your loads. Many crews use 1/2, 5/8 or 3/4 inch double-braid rigging rope.

Is a Hobbs lowering device worth it?

For crews that rig heavy wood often and want to take in rope or pre-tension lines, many find it worth the cost. For light rigging, a Port-a-Wrap is usually enough.