FORTY years ago, Hamm achieved a milestone in road construction with the first all-wheel steering rubber-wheeled roller. Now, the roller manufacturer has introduced what it claims to be another sensation in the sector with its new generation of rubber-wheeled roller.

“The new GRW 280 inspires with its revolutionary and future-oriented overall concept. The newly-developed series offers excellent compacting quality, plenty of driving comfort, extraordinarily good visibility conditions and the highest of safety standards,” says a spokesman for the German manufacturer, a member of the Wirtgen Group.

Launched in the market with various basic weight ratings of 10, 12, 16, 20, 24 and 28 tonnes, the machine can accommodate different amounts of ballast depending on the basic weight. The outer dimensions are identical for all variants. For all types, the width over tyres is 1,830 mm. The machine has a maximum operating width of 2,084 mm.

“The future-oriented concept behind the GRW has already convinced leading international product designers. In March last year, the new-generation rubber-wheeled roller was awarded the ‘iF design award 2010’ as well as the red dot design award 2010, two of the world’s most important design prizes, for its accomplished ergonomics and functionality,” says the spokesman.

The driver’s cab ... panoramic view.

The rollers are replete with new features that are designed to make compacting better and more convenient, starting with a completely new cab in a new position on a newly-redesigned frame.

The most important new feature for the operator is the large driver’s compartment. Instead of the earlier two seats, there is only one driver seat now. Optionally, it can be moved and pivoted at the side towards the machine’s outer edges and along with the console.

Hamm has also taken new approaches in terms of the operating concept. Operation and display elements are positioned on the console and thus always in the driver’s field of vision. Also, the speed is no longer controlled by an accelerator pedal in the foot space, but by joysticks, which signify a considerable boost in convenience for the driver.

“In total, the new operating concept corresponds to that of a tandem roller. Thus, cost-effectiveness is increased because in the future, operators can switch flexibly between roller types without any adaptation time,” says the spokesman.

A hydrostatic rear-axle drive for the GRW 280 allows for higher speeds during transport and compaction. “To match it, the newly-conceived steered axle at the front with disk brakes ensures the necessary braking force and thus considerable safety when braking suddenly, even with maximum load. In total, sensitive control of the rear axle and an extraordinarily good view of the site and the wheels’ edges enable high compaction quality.

“The totally redesigned frame, an innovative arrangement and the glazed design of the cab are the basis for perfect visibility conditions in the new GRW. The view of the area directly in front of the front axle is also unobstructed. Here, the hydraulic cylinders for level compensation of the front suspension, which used to protrude out of the frame into the driver’s field of vision, have now been replaced with two swing arms between the front pairs of wheels. They require very little space and are not visible to the driver,” he says.

The track offset between the front and rear wheelsets is one of the basic features of the rubber-wheeled rollers. Hamm utilised this fact in the design of the new GRW and designed the machine frame in symmetry with the wheelsets. “This intelligent design offers one crucial advantage because, for the first time ever, the driver can see the wheels on all outer sides. Moreover, viewing channels in the frame structure offer a view of the tyres of the outer wheels. The viewing channels are additionally lit to enable work at night,” the spokesman points out.

One important criterion of rubber- wheeled rollers is the ability to swiftly modify the machine’s weight. The GRW 280 offers large ballast spaces between the wheelsets and a serrated frame that is open in the downward direction. It can be filled with steel or concrete using a forklift truck. “Therefore, the GRW 280 can easily take a total ballast of 10 to 28 tonnes and thus covers all operating options,” he explains. “At the same time, this concept has clearly reduced the loading effort. Incidentally, regardless of how much ballast a GRW 280 carries, thanks to the intelligent ballasting system the distribution of weight to the front and rear axles always remains constant.”

The generously dimensioned brake system ensures the higher-than-average safety standard during driving. When the machine is idle, the access steps to the cab, which are integrated with the outer contour, can be folded out to afford additional safety.

This apart, the machine height is under 3 m, which not only simplifies transport on a low-bed trailer, but also working under bridges, protrusions or other overhangs.