The wider Cat® drum leads to big production gains

Gellini Costruzioni annually mills thousands of tons of asphalt-and paves thousands tons more. What's common to every facet of the paving process is the need for production.  "We are always looking for ways to maximize the use of our equipment, to increase our fleet productivity," says Giampiero Gellini, owner of the firm, based in Arezzo, Italy.

Gellini Costruzioni recently found a key tool for maximizing production while on a cold planing job. The company tested a Cat^® PM200 Cold Planer with a 2.2 m drum, compared with the standard width of 2.0 m.  The results were impressive, to say the least. "We were able to complete the job in four passes, instead of five," said Gian Giacomo Gellini, son of Giampiero and owner of the firm. "That means a productivity gain of 10 percent.  We not only saved time, but also saved fuel. We would have consumed the same amount per pass with the standard drum. The PM200 engine has more than enough power for the wider drum. We were able to increase production and reduce the amount of fuel consumed with one less pass, and reduce the emissions."

Project description
Motorway E78 called "Due Mari," or "Two Seas" Motorway, connects the Tyrrhenian and Adriatic seas. The road is a commerce thoroughfare; besides running between the seas, it also connects the key cities of Grosseto, the chief town of Tuscany's coastal area, and Fano, a coastal resort in the Marche region.  Gellini tested its new wide drum on a portion of E78 in the Tuscany province of Arezzo. The 8.35 m wide road featured a driving lane and a passing lane. Problems in the subbase meant the road had to be rebuilt.

Plans called for milling, recycling and placing new asphalt over a stretch of 1100 m. The Cat PM200 cut at a depth of 23 cm in the driving lane, and 5 cm in the passing lane. The crews used cold recycling techniques to rebuild the subbase. A Cat AP600 Asphalt Paver then placed a 5 cm binder course, followed by a 5 cm wearing course. A Cat CB434 Asphalt Compactor compacted the mat.   

Milling
The PM200 with the wide drum was able to work at the same pace as when the machine had a standard drum. Breakout size was about 30 mm. The millings were delivered via conveyor to trucks. A portion of the millings was hauled to Gellini's plant for recycling at a later date. A large amount of millings were temporarily stored on site and for use in the cold recycling process.

The rotor and pits performed well, the Gellinis said.  Boart bits were used on the rotor. "They typically last about 40 hours on hard asphalt," said Gian Giacomo Gellini. "When a bit is worn out it can be easily replaced. However, every four to five days all the bits are replaced when working on medium-hard asphalt."

Operator Roberto Zelli was impressed by the durability of the bits, as well as the drum's ability to add production given the added width. He also appreciated the easy operation of the PM200. Specifically, he was able to set the grade and slope controls and let them hold their positions.

"I can simply set the depth and go from there," Zelli said.

All other PM200 components and systems were able to keep up despite the wider drum. The water spray system limited the dust and helped keep the bits cool, and the conveyors could easily handle the increased loads.

The wide drum
Gellini was approached about testing the drum in the field, and agreed to do so. The cold planer was taken into the shop, and the standard 2m drum was replaced with the 2.2 m version.

The first test was milling a 2300 m long two-lane section on the Firenze-Siena Highway at a depth of 23 cm.  The work took a total of a week and the results were excellent: The drum improved productivity and reduced fuel utilization without requiring any additional cost or efforts.

"The benefits coming from the use of the 2.2 m drum are clearly highlighted when operating on big projects such as highways and airfields, where the cold planer never stops milling. In this case, you can achieve 10 percent more production" he said.

Gellini Costruzioni had such a project coming up after E78: the milling of the Motorway E45 in Cesena, Northern Italy.  Gian Giacomo Gellini planned to use the wide drum on the job, which will run non-stop for 20 days, and keep more than 20 trucks busy. He looks forward to the use of the wider drum given the results from the Motorway E78 job.

Gian Giacomo Gellini said he has consistent expectations from Caterpillar machines. "We buy based on productivity, product reliability, after-sales Dealer service, and price," he said. "Being able to count on a quick and skilled response from the after-sale service, if needed, enables us to focus on the work, and to achieve the best return on our equipment investment."

The wide drum helped ensure they got the most out of the equipment on the E78 job.

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