Sign of the times: Big loaders get ‘fuel-sipping’ CVT transmission
Doosan has launched its first wheel loader range to be equipped with a continuously-variable transmission (CVT) – namely the new DL420CVT-5.
According to Doosan, the CVT design combines the benefits of a mechanical and a hydrostatic transmission in the same machine. The DL420CVT-5 can apparently transition – automatically – from hydrostatic power (at low speed) to a mechanical system (at higher speeds).
Doosan says that the ability to split hydrostatic and mechanical power has allowed it to move to the Scania DC09 engine in the DL420CVT-5, as the CVT system is said to make better use of the available power.
With an output of circa 315hp at 1,800rpm, the DC09 motor meets Stage IV emission regulations – without the need for a diesel particulate filter.
As with existing Doosan wheel loaders (of this model family), operators can select between several driving modes that adjust the maximum engine rpm based on the operator’s preference and the application at hand.
For example, digging mode is available below 3kph. By pressing a button, the machine makes its “maximum” torque available to the transmission – to boost pushing ability.
Drive mode engages when the machine travels (forward) at over 14kph; the machine shifts into this mode to “decrease fuel consumption”.
All new-generation Doosan wheel loaders have a load-sensing hydraulic pumping system, whereby the variable axial-piston pump generates flow upon demand.
This, says Doosan, affords better traction when, for example, penetrating heaped material; as less force is apparently needed to operate the bucket (or other attachment) in some such situations.