The INTERMAT 2012 event was the setting for Dana Rexroth Transmission Systems to unveil its R3 hydro-mechanical variable transmission (pictured) – the first powersplit system from the new joint venture.
The transmission is said to combine the advantages of a mechanical travel drive with torque converter, with those of hydrostatic travel drive. The former offers high efficiency at fast speeds, as well as maximum torque at standstill; while the latter offers good response, low engine speed and a high level of freedom in terms of power management.
According to initial tests, the powersplit system offers fuel savings of around 20 per cent compared to the same vehicle with a conventional torque converter transmission.
One of the reasons behind the fuel savings is that when the vehicle travels at low speeds, only the hydrostatic circuit is needed; and this assists with quick acceleration and braking without the need for an additional clutch.
Meanwhile, as the vehicle speed increases the power splitter starts to route the engine power through a parallel path – and this helps vehicle acceleration without interrupting the tractive force.
In addition, the hydro-mechanical variable transmission helps to optimise the operating point of a diesel engine as it decouples it from drive speed – while maintenance costs are also reduced using hydro-static braking and wear-free directional reversals.
As an added bonus, the system is said to reduce complexity for manufacturers as it is managed by an advanced electronic control unit.
