Erecting Mobile Opportunities
August 17, 2005 • The acquisition of the French manufacturer Potain in spring 2001 was a perfect fit for the Manitowoc Crane Group (MCG), Manitowoc, Wis. Potain tower cranes, along with Igo self-erecting cranes, were the company's first step to broadening its product line and giving MCG a stronger presence in Europe. Other brands in the MCG portfolio include Manitowoc crawler cranes, Grove rough-terrain and all-terrain cranes, and National boom trucks.
Of the newly acquired product lines, self-erecting cranes seem to be making the biggest impact in the North American market. Self erectors, which should not be considered tower cranes, erect themselves from a compact transportable package into a fully functional crane. The Igo MA series includes two models — the largest of which is the MA21. They're selling so fast MCG can hardly keep them in the yard. Meanwhile, I recently reviewed the smaller MA13 (Image 1) at the company's demo yard in Shady Grove, Pa. This is the first in a two-part series on the Potain Igo MA13.
Self erectors are so new to the market that there has been some confusion about how to classify them. Many mistakenly label these cranes as tower cranes because of their ability to reach up and over at a 90° angle. In my opinion, that's where the commonality between self erectors and tower cranes ends.
The Igo MA and similar competitive brands are highly transportable mobile units. Tower cranes are not mobile in the same way. Tower cranes can climb to various heights, while self erectors work at a fixed height. Tower cranes, most often, are operated from cabs at the top of the mast. In the case of the Potain MAs, self erectors are capable are operated by radio remote control, which allows the operator to be at the safest and most favorable position while loading and placing materials.
MA denotes that this unit is permanently mounted on a set of tandem axles. Specifications include 68'3"maximum hook height attained with a jib manually offset at 20°. With the jib in the horizontal position, the hook height decreases to 52'6". Maximum operating hook radius is 72'2", but the jib can be folded back for operation in tighter areas, reducing the radius to 34'5". Maximum capacity is 3,968 pounds.
A key attraction of the MA line is that it is intended for single-person erecting, transporting, and operating. I was eager to find out if this was indeed the case when I tested the MA13. Although my test unit was a base model, there are only a couple of options to note, including painted components in lieu of galvanized steel and larger nylon outrigger pads.
Mobility
Weighing in at a very roadable 23,000 pounds, the MA13 can be towed by a properly equipped medium-duty truck, such as the Ford F-650. The Igo MA13 is equipped with airbrakes featuring an electrically modulated ABS system. Accordingly, any towing vehicle must support air brakes and ABS.
A pintle hitch is required with a minimum 1,000-pound tongue capacity. The tongue is located on the lower section of the main boom, moving into position when the boom is fully stowed. This design prevents someone from attempting a pick-and-carry lift, which the crane is not designed to do.
Each unit comes with a set of universal hook-up adapters intended to work with any brake and light plugs. Once the crane is properly stowed, all you need to do to transport it is back up your truck and hitch it up (Image 2). It's no more difficult than hitching up a boat. The recommended top towing speed is 50 mph. High flotation tires help negotiate soft or muddy ground conditions.
Erection
Once the unit is in position, the operator's task turns to finding a power source for the electric crane • three-phase 480 VAC at 32 amps or single-phase 220 VAC at 20 or 32 amps is required. Connections are provided for both voltage options (Image 3).
While AC power in an urban application is rarely a problem, the versatility and transportability of self-erecting mobile cranes means they are often taken to remote locations. When power is not readily at hand, a 15-kW generator set does the job. According to MCG, some buyers are mounting the gen-set directly to the crane.
Quiet operation is a direct benefit of electric power, which is especially important in urban environments. The MA13 was so quiet that sometimes I forgot it was moving.
Once you are familiar with the process, it should take about 45 minutes to set up the MA13. I learned that at least half this time is devoted to setting the outriggers and leveling the unit.
To hold costs down and keep operation and maintenance as simple as possible the outriggers are manually deployed both horizontally and vertically. After they have been swung out and pinned at right angles to the frame, the operator must crank them down. Although the outriggers feature two-speed jacks, the process is time consuming and physically taxing. While self-erecting cranes often stay on projects for weeks or months at a time, their high mobility makes them ideal for being taxied to several jobs a day. If that were the case, I personally would not want to go through the outrigger set-up process more than a couple times a day.
Apparently, some of the more ingenious self-erecting crane owners have adapted an electric drill to speed and ease the process. I suggest that Manitowoc take a cue from them and offer a purpose-built electric drive option.
A bubble sight gauge assists with leveling the crane, but there is only one, forcing you to walk from
side to side to check your progress. A duplicate gauge on the other side of the machine would save a lot of steps and perhaps a few minutes of set-up time.
After that, the crane does the rest of the work. First the counterweight is repositioned. The counterweight is carried on the unit at all times, and no additional weight is required. A single hydraulic cylinder (Image 4) transfers the counter ballast from the transport position (folded into the center) to the operating position (away from the center). Finally, the remaining crane erection takes about eight minutes (Image 5).
It was actually quite fascinating to watch all the pulleys, cables, and hydraulic cylinders work in concert as they unfold the compressed Igo MA13 into a towering structure.
Next issue
In Part Two, coming in the next issue, watch for my operation and service evaluation of the Igo MA13.
