Hybrid solutions combine different technologies in a single system – in the case of cars, at the present time this generally means an internal combustion engine and an electric motor. HAMM, the innovation pioneer, has instead combined an internal combustion engine with a hydraulic system for the tandem roller. This has enabled HAMM to become the first roller manufacturer to develop a machine ready for series production – the HD+ 90i PH, which weighs 9 tonnes.
Hybrid power train: Maximum performance despite a smaller engine
The underlying concept is based on the realisation that although the maximum load is called for regularly while compacting, it is always just for a few seconds at a time. This typically occurs when starting up or activating the vibration or oscillation for example. All other compaction tasks call for significantly less power. This is the reason why HAMM has equipped the power hybrid roller with a smaller diesel engine in combination with a hydraulic accumulator to satisfy the load peaks.
The hydraulic system works rather like a pumped storage power station: As soon as the power demand falls below the maximum load of the internal combustion engine, a pump fills the hydraulic accumulator. If a lot of power is called for, the hydraulic system functions as an auxiliary drive, able to supply a maximum short-term load of up to 20 kW. Following this the cycle begins afresh with the refilling of the accumulator. The principle functions splendidly because the maximum power is usually only called up for a matter of seconds. This leaves enough time to reload the accumulators. This technology allows the roller to deliver the same power while equipped with a smaller diesel engine. With the HD+ 90i PH, two further components also relieve the burden on the diesel engine: An efficiency-optimised electric fan drive and an efficient start-stop system. This means that a 55.4 kW engine output suffices for the HD+ 90i PH, instead of the 85 kW unit in the "conventional" version.