348 H5 performs slick pick

The real challenge to the project for Digging & Rigging, Inc., the massive Link-Belt 348 HYLAB 5 crane’s owner, was not in its assembly or even in the self-erection of its 435’ long boom and jib combination. The “white knuckle” concern was in walking the massive machine about 300 feet, as the crow flies, from the assembly area to the tower site.

There was an incline of slightly over 13% or seven degrees uphill on a freshly excavated dirt roadbed that had to be negotiated during the move. The entire travel across the asphalt parking lot on timber mats and up the wet dirt slope went smoothly.

The weather was the only factor to adversely affect the progress of the job. It rained over three inches the first nine of the 12 days of April causing difficulty and delay in assembling the crane and the segments of the tower. For understandable safety reasons the Wolf erection tower technicians do not work in the rain.

There was also a slight concern about the transition of the heavy 348 crane from the timber mats to the recently cut earth road but that, too, went without incident. The Link-Belt crane’s powerful six cylinder 476 hp Isuzu BB-6WB 1XOB-01 diesel engine had power to spare. Jim Gregory, Jr., Digging & Rigging’s vice president, lowered the boom slightly (10-15 degrees) as he made the climb so as to better enhance the machine’s overall balance. “We inched up the slope without hesitation, idling at 800 rpm.”

“The ergonomics of the new 348 HYLAB 5 operator’s cab is a delight. Being wider and longer, it has more room. The 20 degree tilt capability was important for comfort and safety during the erection of the 450 foot tall MPT television tower. The operator’s view is excellent. The controls are strategically positioned for maximum operator availability. Overall, this new crawler crane has to rate high operator marks,” said Dennis Caniford, who erected the tower segments and walked the big crane back down for disassembly.

The crew assembling and erecting the Link-Belt 348 HYLAB 5 crawler crane, with its combined long reach boom and jib, actually encountered only one problem. They had to remove some of the paint in the bolt holes. Other than that it was a professional textbook operation.

Sixteen flatbed truckloads hauled the crane’s components from Digging & Rigging Inc’s Hagerstown, MD yard over the interstate highway system to a closed MDOT truck scales parking area, just off southbound lanes of I-270 near Hyattstown. Even then, only the base crane’s 12’ wide load required an over-the-road police escort. The tracks, counterweights, boom and jib sections arrived on site unescorted.

The dictionary defines the word “slick” as deftly executed and/or adroit. And that best describes the Digging & Rigging operation in reassembling the crane to erect the new self-supporting television broadcast tower.

The overall project, according to Carl Wolfe, Chief Engineer of Transmission & Distribution for Maryland Public Television, was being done for them. The 450’ tower, manufactured by Sabre Communication of Sioux City, Iowa, is one of six that MPT has strategically positioned throughout the state. The reason for the new towers is that the older existing ones are not capable of supporting the new antennas required for digital television transmission. Each site will require a new type of transmitter and antenna. Once the tower was erected, a steel platform was placed on it followed by a 28’ tall antenna, weighing approximately 3500 pounds.

Interestingly, the new tower is one of only two short towers in the MPT system. The other four are all guyed towers in the 800 to 900 foot tall range. The two shorter ones are each located on high hillside sites.

Sabre Communications of Sioux City, Iowa, engineered, fabricated and shipped the tower unassembled to Maryland. They retained Wolf Contractors of Marriottsville, MD to handle the site preparation, foundation construction and tower erection. In the case of freestanding towers, General Manager Dave Wolf said that they are normally self-erecting, using an ascending gin pole to raise them as they go.

In this instance, however, time was of the essence. Having Digging & Rigging, Inc. use their Link-Belt 348 crawler crane do the work, the project was completed in days instead of weeks because the tower placement was already a year behind schedule. The crane method was also chosen because it is considered a safer method. The tower was prefabricated on the ground in sections and these were then assembled in the air.

Wolf excavated the base support pad foundations and placed the heavy reinforcing steel in them. They then contracted TBK Concrete Construction Co. Inc. of Edgewater, MD to supply and pour 396 cubic yards of concrete for the foundation.

Wolf crews assembled and erected the first 100 feet of the tower from the ground with the assistance of Digging & Rigging, Inc. cranes, including a Link-Belt HTC-8660 and a 150 ton machine to erect the next three tower segments. The triangular tower’s base section has three 39-foot wide faces. Each leg was fabricated of solid steel as per state specifications rather than from the more conventional hollow steel pipe. These were set individually and connected together on the ground.

Digging & Rigging, Inc. then moved in their new Link-Belt 348 Hylab 5 crawler crane with its long reach lattice boom and jib. The first lift made with it weighed 12,770 pounds. This 20’ tall section of the triangular tower had three faces, each 25 feet wide. The crane was working at a 92’ radius with a boom angle of 82 degrees.

The final section of the tower weighed 14,700 pounds and was 90’ tall with faces 9’ wide at the bottom and 7’ wide at the top. This was the heaviest and highest lift on the tower. To facilitate its balance and vertical placement, the crew positioned the lifting slings on this section 25’ below its top, giving operator Dennis Caniford all the challenge he could handle, considering the crosswind blowing at the 360 foot tower elevation and the safety of the three Wolf tower technicians waiting to make the final connection.

Digging & Rigging, Inc. was founded in 1981 by James E. Gregory, Jr. as a local excavation company with one Case loader/backhoe and a single axel dump truck. Then came their first crane.

Now they are essentially a crane rental service, doing very little dirt work. Susan Gregory, Jim Jr’s mother, is the firm's president. He is vice president and his father, Jim Gregory Sr., is general manager.

"We are considered to be a comparatively small specialized company. We work primarily in Maryland, Virginia and the District of Columbia area. However if the job is right for us and we have the cranes for it, we are available to undertake it anywhere. We have a select client list of repeat customers who we have served over the years. They come back to us often because our philosophy is to do whatever we do right -- the first time," said James E. Gregory, Jr.

"Our equipment ranges in size from a 15 ton Broderson Carry Deck machine all the way up to a 365-ton capacity all terrain hydraulic truck crane. We own six Link-Belt cranes and have depended on them for the past ten years. Digging & Rigging, Inc. had the first 200-ton Link-Belt machine with the luffer attachment. A few short years later we bought a second one because of its ability to adapt to various projects and its dependability,” said General Manager Jim Gregory, Sr.

“The company also owns several smaller Link-Belt hydraulic truck cranes, too. We own this brand of cranes because they have proven to be very powerful, efficient and reliable machines,” commented Susan Gregory, president of Digging & Rigging, Inc.

The final move at the television tower was to walk the massive Link-Belt 348 crane down from the tower site to the truck scale parking area where it was disassembled. The reverse procedure was used and it, too, went without incident. Observers at the location timed the downhill speed at “four crawler pads or 52 inches in thirty seconds.”