Pole-Pulling Innovation.
Published in: Transmission & Distribution World
Date: 4/1/2006
By: Kysely, Joe
A high percentage of the new utility poles that We Energies is installing are going toward replacing existing poles, rather than for new pole lines and expanding the system. Road-widening projects, for example, force electric utilities to relocate their existing facilities, replacing and relocating fairly new and reusable wood poles. All of these situations necessitate the removal of poles, a labor-intensive procedure I have struggled with for years.
For a mid-sized utility, the pole removal and replacement may be as many as 10,000 poles per year. At a removal cost of approximately $150 per pole for a three-man line crew, this can equate to $1.5 million per year just for pole removal.
In each of these cases, the old pole has to be removed. On a road-widening project, the electric utility will install a new pole line and string in new conductor along the edge of the new road right of way. Once this line is energized and electric customers are cut over to the line, the electric utility will remove the old wires from the existing line and cut the top of the poles off just above the telephone and cable TV circuits. This allows the owners of the communications circuits to lift their facilities over the top of the cutoff pole and transfer their facilities to the new poles without cutting and splicing. Once the remaining facilities are relocated, the old poles need to be removed and the holes left by the pole butts filled in.
Pulling Device Inadequacies
The commercially available pole-pulling devices we have seen and used in the past serve their purpose, but sometimes end up being a wrestling match to deal with both before and after the pole is out of the ground. They typically include a hydraulic cylinder and a base-plate assembly that is coupled to the pole via a chain that cinches it. For inaccessible jobs such as rear-lot line applications, the cylinder and base-plate-type device needs to be carried by hand to the pole and then assembled. A separate portable hydraulic power source also has to be carted to the pole as well. The chain-cinching mechanism can also be difficult to operate because the chain tends to not “bite” and roll as the cylinder is extended. This requires the crew to install a wedge block – driven in with a sledgehammer – between the chain and the pole to keep the chain from slipping.
These devices involve a “multistroke” procedure. Once the hydraulic cylinder, typically 18 inches to 24 inches, is fully extended, the wedge block needs to be driven back out with a sledgehammer, and the cylinder then needs to be retracted and reattached to the pole. This can be a time-consuming and labor-intensive operation, not to mention the issues that arise when you are dealing with a wet, muddy, slippery pole.
This type of hydraulic cylinder puller also has a tendency for the base of the cylinder to sink into the ground. Since the hydraulic force is engaged on one side of the pole, the pole has a tendency to tip away, sometimes in unwanted directions. And, if you are using a portable-type puller, you need to either support the pole from above in some way or cut it off just above the ground line; otherwise, it is likely to topple over once it is fully extracted.
To tell the truth, because of these operational difficulties, utility line mechanics tend not to use them. In the interest of saving their backs, pole crews tend to look for alternative methods that are not necessarily the safest ways to extract poles. For example, a common solution you won’t find in the operations manuals is to try to loosen the pole by wiggling it back and forth with a digger derrick truck, and then extracting it with the digger derrick’s winch line. These kinds of shortcuts can damage the crane boom-and-turret assembly, which was obviously not designed for this type of procedure. Going beyond the design limits of the boom truck also becomes a major safety concern.
Pole Crew’s Wish List
The whole pole removal process has been a concern of mine for several years. What I was really looking for was a machine that could pull, control and lay down a pole in a single operation without operator intervention. I also wanted it to be self-contained and machine transportable to eliminate having to carry it around by hand. Unfortunately, the machine I was looking for didn’t exist – yet.
Several pulling devices on the market addressed one or more of the concerns I had, but not all of them. For example, there is a unit with mechanical fingers that applies concentric gripping, which addresses the chain slippage issue. There is also a device that can extract a pole with a single stroke using a rather long, cumbersome hydraulic cylinder, although the cylinder is heavy and the cylinder rod is susceptible to damage. Another type of pulling device I have seen mounts the hydraulic cylinder in the bucket of a rubber-tired backhoe or skid steer, making it transportable. Obviously, it has limited accessibility, but I can’t argue with the stability of the unit during extraction.
The Mother of Invention
Recognizing that there was only one way to solve my problem, I finally sat down at home and designed a pole puller that would safely and efficiently extract a utility pole in a single stroke of the hydraulic cylinder, while holding the pole and laying it down once it was out of the ground. To minimize the manhandling of the pulling equipment, I designed the puller to mount on the three-point hitch of a compact four-wheel-drive utility tractor. The tractor hydraulics also serve as the hydraulic power source, making it a self-contained unit that is ideal for back-easement work. I call it the Polematic.
Quite honestly, the idea for the design came from the logging industry. Commercially available forestry-processing equipment can maneuver up to a tree, grab it, cut it off at the base and lay it down, all in a matter of minutes. And the operator never leaves the cab of the machine.
Granted that pulling poles around high-voltage lines is a little more complicated than cutting down trees, my patent-pending pole puller incorporates a standard, quick-coupling, logging cable choker as the means of attachment to the pole. The cable choker is a foolproof attachment that allows the cable to cinch tightly around the utility pole, regardless of the pole diameter or concentricity. I found that stranded cable has an advantage over link chain in that the cable will “bite” into the wood without damaging it. This is important for poles that will be reused.
How It Works
The mechanics of the cable choker assembly is complicated, but basically it involves a cable-sheave slider-block assembly that generates twice the travel of the pulling action as that of the hydraulic cylinder. The hydraulic cylinder’s 3 ft of vertical travel is translated into 6 ft of travel on the choker end of the cable. This allows a pole butt that is buried in the ground 5 ft to 6 ft to be fully extracted in a single stroke of the hydraulic cylinder. Also, as the pole is extracted, the cable choker end is drawn up close to the upper frame of the machine, thereby providing good control of the pole.
A secondary hydraulic-tilt cylinder, also attached to the pole-pulling apparatus, maintains vertical alignment and can be adjusted for situations where the off-road equipment is not on level ground. Once the pole is nearly extracted, both of the loader-bucket tilt cylinders tilt the pole away. A V-shaped member near the bottom of the pole puller captures the pole butt and provides control while the pole is being laid down. Once on the ground, the cable choker can be re-hooked at the center of gravity on the pole and the pole can be loaded directly onto the pole trailer, thereby eliminating the need to set up the digger derrick truck to load the pole.
In addition to being able to control and lay down the pole, we found that the tractor also is capable of transporting an extracted pole butt to an accessible location. We are exploring the possibility of mounting a side-dump gravel hopper to carry fill dirt for backfilling pole holes. We are currently filling in pole holes with bags of gravel – by hand. Another possibility we’re considering is mounting the pole puller on the front and the gravel hopper on the back, thereby removing the poles and filling the holes all in a single operation. Mounting the puller on a small rubber-tired compact utility tractor also has the advantage of not tearing up the customer’s yard, requiring restoration.
First Results
After several field runs and additional refinements, we have completed the first production model, which we have mounted to the quick-detach bucket of a rubber-tired backhoe. We Energies purchased the first unit and has been using it with its project crews for approximately 6 months.
The feedback from the field personnel, operations supervisors and safety folks has been positive. As one of the younger linemen, who used to have to drag the old conventional puller by hand to the pole, said, “This thing is awesome!” We have yet to see anything like it on the market today. The telecom folks are also very interested in the machine. In the interest of not carting a pole-puller-equipped backhoe all over the system, We Energies is currently in the process of procuring a second unit.
We want to make sure that we have all the kinks out of the unit before I make the Polematic commercially available. The cost of the unit will be around $15,000. We figure that the payback period can be short based on time and labor savings alone. The safety and ergonomic benefits are hard to measure, but how do you put a price tag on safety and ergonomics?
Joe Kysely is senior application engineer at We Energies, where he is responsible for the design, startup and maintenance of electric distribution facilities. He has 15 years of experience as an electric power engineer, having worked as a design engineer on high-voltage switching equipment at S&C Electric Co. (Chicago) and as a senior design engineer doing development work on distribution transformers at Cooper Power Systems. Kysely is a member of IEEE and a registered professional engineer in Wisconsin. He has a BSEE degree from Marquette University and an MEEE degree from Rensselaer Polytechnic University. joe.kysely@we-energies.com
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