According to Hamm, its GRW 280 pneumatic roller is "a revolutionary new design that represents a new generation of rubber-tired rollers."
For example, the roller features an opening in the frame, what Hamm calls a "viewing channel," that provides operators a view from the cabin of the contact surfaces of the outer wheels. Also, the front-wheel suspension design allows for an uninterrupted view toward the front.
Also contributing to improved visibility is the addition of a single operator seat that has replaced the two seats, two steering wheels, and two control consoles in older models, all of which could understandably restrict freedom of movement. The new seat can also be moved and pivoted at the side toward the machine's outer edges and along with the console.
Display elements are positioned on the console and thus always are in the operator's field of vision. Speed is no longer controlled by an accelerator pedal but by a joystick, which is expected to contribute to increased productivity for the operator.
A hydrostatic rear-axle drive for the GRW 280 will allow for higher speeds during transport and compaction. To match it, a new front steered axle with disk brakes allows for the necessary braking force when braking suddenly, even with maximum load.
The operator’s platform sits on a newly designed asymmetrical frame, while the longitudinally installed engine is situated in the rear of the machine. In the past, hydraulic cylinders for level compensation of the front suspension protruded out of the frame into the driver's field of vision. They have been replaced with two swing arms between the front pairs of wheels, which require very little space and are not visible to the operator.
The track offset between the front and rear wheelsets is one of the basic features of pneumatic rollers, knowledge that Hamm used in the design of the new GRW's machine frame. The frame is in symmetry with the wheelsets, allowing the operator to see the wheels on all outer sides. That feature adds to the visibility advantages of the viewing channels. The viewing channels are illuminated to ease work at night.
Rubber-tired rollers need to be able to have their weight modified swiftly and easily. To this end the GRW 280 offers large ballast spaces between the wheelsets and a serrated frame that is open in the downward direction. It can be easily loaded with steel or concrete. Hamm says that due to an intelligent ballasting system, no matter how much ballast a GRW 280 carries, the distribution of weight to the front and rear axles always remains constant.
Each GRW 280 can accommodate different amounts of ballast depending on its basic weight rating—10, 15, 20, 25, and 30 ton (9, 14, 18, 23, and 27 t). Outer dimensions are identical for all variants; all the machines are under 10 ft (3 m) in height, simplifying transport on a low-bed trailer and easing work under bridges, protrusions, or other overhangs.
Safety features include what Hamm describes as a "generously dimensioned" brake system, ROPS, and integrated folding cab-access steps. The steps also can be swiveled to provide convenient access to the maintenance platform next to the engine. Hamm designed all maintenance points to be on the engine's right-hand side.
The GRW 280 is equipped with a four-cylinder Deutz engine with a 134-hp (100-kW) output and a common rail injection system. It meets Tier 3 requirements.