Improvements on Cat® RM300 give road maintainers a boost
Australian shires and councils increasingly face pressures to keep roads properly maintained. At the same time, they also are expected to minimize spending.
Two governmental bodies are turning to the Cat® RM300 Rotary Mixer to help reduce costs while keeping roads in proper condition. Recently taking delivery on Cat RM300 Rotary Mixers were Longreach Regional Council, Longreach QLD, and Murray Shire Council, Mathoura, NSW. Both agencies report the machines have helped them boost production and limit costs.
All aspects of road building—from design to asphalt or tar seal—are undertaken by the council. That has been the case for many years.
"We hired our first reclaimer in 1990 to perform road construction within the shire," said David Hislop, workshop manager for Longreach. The reclamation process proved effective enough that Longreach purchased its own reclaimer, a Cat RR250B, in 1998. Success with that machine led to the latest purchase of a Cat RM300.
On the job
Hislop and his crew recently put the new machine through its paces on a road project 10 km south of Longreach. The RM300 tackled a section of road 20 km in length and 5 m in width.
"The job is an on-site mix of the existing road base, which is then covered with tar seal," Hislop said. "Cement is mixed into the base to a depth of 250 mm by the reclaimer. All extra materials are trucked in side tippers, shaped with the grader and then the reclaimer."
Crews immediately noticed improvements with the new machine. "The sliding cab has great vision to both the left and right, and there is great access when going from the left to the right sides—or the opposite," Hislop said. "The cab also is very spacious."
In addition, the increased power was noticeable. "The extra weight of this unit has made pushing tankers around a curve very good," he said.
This job, like most, required only a single pass by the reclaimer. "If we do require a second pass, we work in the opposite direction," Hislop said. "This helps give us a very even mix." Helping with the mixing is the Universal Rotor with quick-change holders.
Council crews follow the reclaimer with a padfoot, and then smooth drum, rollers. Compaction is typically achieved in about eight passes. "The rollers follow right behind the reclaimer," Hislop said. "The first two to three passes are on high amplitude, and then low. It varies based on the materials being compacted."
Production varied, based on the application and materials being reclaimed, but Hislop is pleased with it. During a typical workday, about 1700 m were compacted at a depth of 200 mm. "This is finished, trimmed and compacted," he said.
The reclamation process can lead to significant savings. The existing surface is recycled, saving on the purchase of new aggregate and the associated hauling costs.
Hislop said the reclamation process costs about 70 percent as much as traditional road construction. "There are additional savings in water transport," he said. The life of the road is about 10 years, he said.
Murray Shire uses the RM300 in varied environments. "It has to be versatile," said Ossie Costello, the shire's works manager. "We have rural roads, country roads, but we also do urban work as well."
The machine might be on one type of job—and working on a particular surface—for only a single day. While some jobs last days or weeks, it is not unusual for the machine to be at three different locations in a single workweek.
"Yesterday it was working on an unsealed road, combining sand and clay," Costello said. "Today it's combining crushed rock and gravel. The next week it will be ripping up a sealed road, readying us to do a full rehab. We also know we can bring it into an urban street and run it up against curb and gutter."
In fact, the RM300 has provided an unforeseen boost to relations with citizens in the urban settings. "It's a lot quieter," Costello said. "It really is a quiet machine, which tracks well in the urban areas."
Working with the shire's clay is a challenge Costello and others knew they had to meet, and was certainly a key purchase consideration. This led them to buy an RM300 with a rotor with specific design considerations for clay. That decision is paying off.
"We use the RM300 to combine sand in with clay on unsealed roads," Costello said. The rotor also is productive in other applications where clay is not as prevalent.
The automated system efficiently controls the amount of water or other liquids that are mixed. "The controls for the water automatically match the speed," Costello said. "If the machine goes faster, there is enough water. If the machine slows, you don't waste water."
The improvements have made the crews more productive. They are able to reclaim one-half kilometer per shift when working on pavement. "When we're working on unsealed roads, we can double that," Costello said.
The machines typically work at a depth of 200-300 mm. "There is enough power," Costello said. It also holds the proper grade and slope. "The operator can set the depth and the (fluid) controls and leave them," Costello said.
They also can see what they're working on. "The cabin moves across the machine so you have the ability to see what you're doing from either side," he said. "The cabin ergonomics also are improved."
That and the other changes have all made a significant difference, both Hislop and Costello agreed.
"It moves quickly and gets the job done," Costello said. "The RM300 was a good decision."Ω
The Cat equipment product line, consists of more than 300 products for the construction and mining equipment, diesel and natural gas engines, industrial gas turbines, and has a wide offering of related services.