Contractors no longer use compact double-drum compactors only for the smallest of jobs. While they are still useful for bike paths, driveways, parking lots and sports courts, these machines – which feature a drum width of 40 inches or less – now tackle a variety of asphalt surfaces including municipal roads and the compaction of sublayers and finish layers on road repair.
Work smart, not hard
Hamm’s compact models, the HD8VV and 10CVV, which have 31 1/2- and 39-inch drum widths respectively, have single drum support and are cantilevered, eliminating the time and expense of following up with a handheld machine – an issue their customers asked the company to address. “The front drum is only supported on one side, so you can put the side of the drum right up against a wall or other obstruction,” says Bruce Monical, marketing manager, Hamm Compaction Division, Wirtgen. “Previously, you’d compact as close as you could, but then you’d have to come in afterwards with a vibratory plate compactor to finish the edges.” The offset drums have more than one advantage – the operator can compact at the edge with one drum and still leave the other drum with enough room to enable the operator to drive away from the edge, while the cantilevered design gives the operator an additional two inches of compaction width.
Multiquip has also addressed the issue of paving against walls and curbs with their Rammax AR Series, designed for sub-layer granular and mixed soil projects as well as asphalt compaction. All models in the series feature offset drums for clearance against obstructions, including the AR12, with a 32.3-inch drum width, the AR16, which has a 35.4-inch drum width and the AR20 and AR23, both with 39.4-inch drum widths.
Wacker Neuson also addressed productivity and maneuverability in their latest models, introduced in 2007. The RD12 and RD16 compact closer to the surface’s edge than before, says Rebekah Gallert, product manager, compaction and demolition products, Wacker Neuson. “These models have no front or rear overhangs, which allows the operator to compact to the very edge of the asphalt,” she says. The compactors’ articulated steering reduces marks left on the asphalt. The company also improved the machines’ turning radius from previous models, providing added maneuverability in tight places, Gallert says. To further increase productivity, Gallert recommends using a dual drum drive machine. “The dual drum drive combined with articulated steering offers maximum traction with accurate control without ‘shoving’ the asphalt,” she says. “Since both drums have drive capability, the roller is better able to handle inclines without getting stuck.”
Volvo’s 2 1/2-ton DD22, which was introduced to the U.S. market at last month’s ConExpo-Con/Agg, features a 39-inch drum width. Ray Gallant, director of product planning, Volvo Construction Equipment, Road Machinery Business Line, says the machine addresses their customers’ three basic demands – versatility, ease of operation and easy serviceability. “We watched how customers use the machine to see how the compactors could be improved,” he says. “We went out and traveled with them, and discovered moving from site to site was sometimes as much work as the job.” As a result, Volvo incorporated an optional traction valve for loading and unloading. The DD22, like the other models in the Volvo line, has a new engine platform which will be Tier 4-compliant in 2008. Since simplified maintenance was a key customer request, the machines now have color-coded electrical wiring and Volvo has rearranged the engine compartment for unobstructed access. “With small machines such as this, everything is tight. We’ve moved all the fluid tanks to the bottom of the frame, so now when you open the hood, all you see is engine,” he says.
Gallert says a range of features on the RD12 and RD16 lets operators improve performance. “A pressurized water system with eight position timers allows the operator to adjust the water flow to match the conditions,” she says. “By using only the water needed, less water is wasted which reduces the frequency of refills.” Wacker Neuson has also increased the exciter frequency on their compact line, enabling operators to compact at higher speeds while avoiding ripples.
Monical says the single most important upgrade to Hamm’s compact line, which hadn’t changed substantially since its introduction in 1995, was its engine change to a water-cooled Hatz engine. “The water-cooled engines are popular and a bit easier to work on than our previous air-cooled engines, so it was a natural transition for us.” The entire product line features diesel engines. “Diesel is not as combustible as gasoline, so we made the decision from a safety and consistency standpoint,” Monical says.
New models also offer improvements in ease of operation and serviceability. “Our engine enclosure has a low contour that provides improved visibility to the front and side, which allows the operator to work more accurately,” Gallert says. “We have also increased operator leg room while decreasing vibration, lessening operator fatigue.” The company has also included a single-servo hydraulic control lever for smooth starts, and a built in exciter control switch. A tilting rear platform provides easy access to service points.
Hamm’s Monical says their compact product line underwent important safety upgrades. “We’ve made the machines standard with a seatbelt and ROPS protection,” he says. “All the models have a horn, back-up alarm, front and rear worklights and flashers.” The company’s engineers also implemented control consistency throughout the compaction line. “If you’ve been operating our bigger machines for years, you should be able to switch to the smaller machines with no learning curve,” he says. “The opposite will also be true. If you’re a small contractor using the compact machines, your operators will be able to use the controls on the large machines if you need a bigger machine.”
Having options available for the compact line that are similar to those on the heaviest rollers improve performance under a variety of jobsite conditions, Gallant says. Volvo’s DD22 has a full range available, including dual joysticks, edge cutters, an offset center articulating joint, different light packages and folding and fixed ROPS and FOPS.
Multiquip has attended to operator comfort and convenience by adding a variety of standard features to the AR Series, including a back-up alarm, low fuel warning light, dual vibration with a rear vibration cut-off switch, a dual water filtration system, sound attenuation and a vibration-isolated platform to minimize operator fatigue. A lockable instrument panel and engine cover ensures security, and a folding ROPS simplifies transportation and improves clearance. Articulation joints with permanently sealed bearings are maintenance free and a lightweight hood enables simple servicing and engine access. Adjustable centrifugal forces ensure maximum versatility.
Around the corner
Vibratory models remain a popular choice – with good reason, says Monical. “These models offer vibration in the front drum, rear drum, both drums together or can run with no vibration,” he says, noting the versatility increases productivity while reducing the chance of over-compaction. “No one has come up with anything better than the vibratory machines.”
Gallert agrees, noting that the vibratory rollers achieve the best results.