Hamm’s first fully electric battery-driven tandem rollers form part of its HD CompactLine series. Some models are fitted with oscillation drums, including the world’s first e-combination rollers featuring oscillation. Not only is compacting with these machines emission-free, it is also ultra-quiet.
There are eight electric rollers in this compact class. The HD 10e model (drum width: 1.00 m, operating weight: 2.5 t) and the HD 12e model (drum width: 1.20 m, operating weight: 2.7 t) boast the same compaction power as their combustion engine counterparts, but produce zero emissions. The e-rollers are operated in exactly the same way as the other models in the HD CompactLine series.
One Li-ion battery (with a capacity of 23.4 kWh) provides the energy for the travel, steering, and vibration or oscillation drives via a 48-V system. Staff do not require any specialist training or qualifications to operate the low-voltage system, said Hamm. The battery can be charged via a rapid-charge plug (400 V, CEE) or a standard plug (230 V, earthed adapter).
To charge the battery from 0% to 100% takes around four hours (with 400 V), or around 7.5 hours (with 230 V). The battery is designed to operate in ambient temperatures of up to 45 °C and provides enough energy for one typical work day.
The vibration or oscillation unit is driven by electric means only via specially designed, compact synchronous motors. As a result, the efficiency rating more than doubles and the energy demand reduces accordingly too. The electric drive motor and steering motor power a hydraulic system.
All e-components require no maintenance and offer high torque. The concept ensures the power is always available to deliver peak performance on demand. Furthermore, a large portion of the braking energy is fed back into the system by means of regeneration.
The Hammtronic control system monitors and controls the components of the zero-emissions rollers. Combined with the electronic driving levers, this makes the machine extremely easy to control with precision. Speed ramping is also implemented to ensure smooth accelerating and braking manoeuvres.
Hamm has fine-tuned every aspect of the e-rollers to preserve resources. For example, the models feature an automatic electric motor stop as standard. This deactivates all functions when the machine is idling, thereby reserving precious battery capacity. When Eco mode is selected, the control limits the working speed. This also saves energy, as does the LED lighting, which is fitted as standard.
The innovative steering control helps to conserve energy as well – in the parking position, it uses no energy at all. The steering motor does not switch on until the electric driving lever is actuated. Then the machine steers with sensitive responsiveness and an adaptive energy supply with no additional effort.
Combination e-rollers with oscillation
Four of the e-models feature oscillation drums, two of which are combination rollers. This is where the already quiet oscillation meets with the quiet e-drive. The result of this is quiet compaction machines that produce no emissions and cause very few vibrations in the surrounding area. They are ideal for compacting in noise-sensitive and vibration-sensitive areas, such as near hospitals or historical buildings.
All electrical components in the e-rollers are completely maintenance-free. According to Hamm, the extensive electrification reduces the oil volume by more than 70%. Across the entire system, there are very few wear parts that need to be greased or that could suffer from abrasion. This means there are refreshingly few service points on the e-rollers compared with the diesel counterparts. The operating hours registered are also lower than on the diesel-engine models, because the operating hour meter is not activated until the driving lever is moved.
At bauma last year, Hamm displayed two models: the HD 12e VO, a tandem roller with one vibration drum and one oscillation drum, and the HD 12e OT, a combination roller with oscillation.
Hamm further revealed that its new electric rollers will initially be available for the European market. The first models are scheduled for delivery in the first half of 2023 to the regions where the EU Stage V exhaust emission standard currently applies. Many of these countries provide government grants to assist with the purchase of fully electric construction machinery as well as the development of the necessary charging infrastructure.
The electric rollers were also presented at the recent Conexpo 2023 in Las Vegas. Hamm said the machines are expected to be available in the US market from the end of 2023.