Through the innovative SMART drum technology, each of these HFA compactors can be used for a wide range of applications. These high-frequency compactors are engineered with eight amplitude settings, using patent-pending technology. Each amplitude setting is automatically adjusted to the highest frequency for that amplitude selection. This enables the operator to use lower amplitudes with higher frequency on thinner lifts to increase productivity with decreased risk of damage to aggregate structure or sub-grade, and higher amplitude with lower frequency on thicker lifts and stiffer materials. This flexibility once required two separate compactors; Volvo technology enables one compactor to provide both ends of the spectrum in performance. Whatever the job conditions, these compactors will always provide the highest productivity.
Other SMART technologies designed into these three compactors include:
• SMART vibration system, which automatically adjusts vibration frequency for both drums to the design frequency for the given amplitude
• SMART propulsion system automatically controls rolling speed for optimum drum impact spacing
• SMART water system not only shuts off water spray whenever the compactor stops moving, but also automatically regulates water-flow rates to match rolling speed
• SMART start, which prevents vibration of the trailing drum on cold or hard pavement surfaces at the beginning of each paving operation, or at transverse joints on bridges or junctions with PCC pavement panels
Making an impact
These compactors are designed to keep up with pavers moving at faster lay-down speeds while maintaining appropriate drum impact spacing, reducing the need for additional compactors on the job.
The Volvo patented impact meter measures the relationship between the compactor’s vibration frequency and its rolling speed to accurately indicate the number of drum impacts per foot. The operator is able to precisely control the optimal rolling speed for the desired drum impact spacing using an easy-to-read, color-coded gauge. This system allows for increased productivity under a wider range of operating conditions.
Smooth operation
Another Volvo performance advantage is chamfered, radiused edges on the drums. This minimizes drum marking and maintains smooth surfaces as the roller makes its passes.
The industry’s best drum wetting system is available on all models. Volvo has an exclusive dual water spray system, which incorporates primary and secondary spray components. Each drum has independent water storage tanks and two water pumps, two primary filters, separate water distribution lines and two spray bars with hand-serviceable nozzles. Better drum surface coverage and reduced misting is achieved with 10 nozzles on each DD118HFA spray bar; the DD138HFA spray bars are fitted with 12 nozzles each. Two 164-gallon (620 L) water tanks are monitored by the illuminated water-level indicator.
In its highest amplitude setting, the DD118HFA has a maximum centrifugal force of 42,070 pounds (187.1 kN). Vibration frequency ranges from 3,000 to 4,200 vibrations per minute (50 to 70 hertz); and the maximum nominal amplitude is 0.031 inches (0.8 mm). The machine has an operating weight of 27,670 pounds (12548 kg). The DD118HFA is powered by a turbocharged and charge air-cooled Cummins 148-horsepower (110 kw) engine.
The DD138HFA has a maximum centrifugal force of 41,720 pounds (186 kN) in its highest frequency setting. Vibration frequency ranges from 2,700 to 4,000 vibrations per minute (45 to 66.7 hertz); and the maximum nominal amplitude is 0.035 inches (0.88 mm). The machine has an operating weight of 30,325 pounds (13,752 kg). A Cummins turbocharged and charge air-cooled 173-horsepower (129 kw) engine provides the compactor’s power.