The Doosan DX520LCA is a 51t machine which comes standard with a 3,5m³ bucket.

The improved Doosan 50t size class excavator is the ideal choice for equipment operators seeking efficiency and better fuel consumption in tough mining and quarry applications.

With its array of features aimed at lower fuel consumption, higher productivity and better cycle times, the improved 51t Doosan DX520LCA has a special focus on reduced total cost of ownership and increased uptime compared to its previous model. It is now available in southern Africa through DISA Equipment, operating as Doosan South Africa, the regional dealer of the Korean original equipment manufacturer (OEM).

The Doosan DX520LCA has been well accepted by the market, according to Chris Whitehead, newly appointed managing director of DISA Equipment, noting that industry statistics show it as the 2015 market leader in its size class. Meanwhile, with the introduction of the DX480LCA he expects to see a similar pattern in the 45-50t size class.

He believes the improved DX520LCA, with its array of features aimed at reducing total cost of ownership for the equipment owner, will further grow the Doosan product’s reputation in this market segment. “Our focus for this year is to furt

her grow our presence in the larger excavator market,” says Whitehead.

The Doosan DX520LCA is a 51t machine that comes standard with a 3,5m³ bucket and a digging depth of 6,25m. Powered by a 238kW Doosan DE12TIS engine, it is ideally suited for quarrying and mining applications, says Whitehead.

The Doosan DX520LCA is suited for quarrying and soft rock mining applications such as coal.

Fuel saver

The Doosan DX520LCA is 5% more fuel efficient than the previous model. Several new features make this possible, according to Whitehead. Typically, the fuel pump tends to supply flow even when the maximum pressure on the system has been reached due to severe working environments and large workloads. Doosan’s Relief Cutoff technology prevents transfer of unnecessary fuel flow, but keeps a desired working level at the maximum value while reducing consumption of fuel. Relief Cutoff technology is said to save between 20-30% of fuel consumption in heavy workload applications.

When the operator takes break with the joystick kept fixed, both the engine and the fuel pump are kept in standby mode with maximum rotation rate and hydraulic power. This results in unnecessary fuel consumption. To address this, the Doosan DX520LCA comes with an optimised lever control feature that prevents unnecessary fuel consumption. The optimised lever control technology effectively controls the fuel pump to prevent fuel consumption when the system is shut down. When operating the joystick, rotation rate of the engine and maximum hydraulic power of the pump are said to increase simultaneously for efficient fuel consumption.

Doosan’s auto idle technology effectively controls the engine, and prevents unnecessary fuel consumption when the motor is in standby mode.  With this feature, you can save as much as 90% of fuel than in operation.

Whitehead also reasons that in most circumstances, it is commonplace that the response time of the system (time for generating rated power from the minimum power) is slower than response speed of the pump. When that happens, the pump is kept in standby mode until the engine reaches the rated power, and this triggers unnecessary fuel consumption. In such circumstances more fuel is supplied to the engine for matching the pump speed with the engine, resulting in increased exhaust fumes. With the DX520LCA, Doosan addresses these flaws with its Engine & Pump Matching technology. Matching response time between the pump and the motor reduces unnecessary fuel consumption as well as exhaust fumes.

The machine comes with an improved heavy duty boom and stick.

Design improvements

Reliability is one major focus in the design of the Doosan DX520LCA. The machine comes with a full quarry and mining spec, heavy duty undercarriage with a reinforced track guard. The undercarriage has three upper rollers, nine lower rollers and three track guards per track frame. “It has an extra durable undercarriage with three upper rollers compared to two on most of the competition’s machines,” says Whitehead. This minimises stress on rollers and track links.

The machine also comes with an improved heavy duty boom and stick. Overall reinforcement of steel on the boom and arm has been achieved through a 20% increased thickness on the side plate and 15% on the bottom. Its 7,1m boom and a shorter 2,9m stick translate into better breakout force, especially in taxing working conditions, says Whitehead. This makes it a perfect fit for running heavy duty attachments such as hammers and crusher buckets.

The Doosan DX520LCA excavator also comes with hydraulic piping for work tool applications as standard. In many of the competition’s offerings, this is said to come as an extra. “This feature alone can cost in excess of R150 000 to install where it comes as an extra,” says Whitehead.

What is more is that the main high-pressure lines from the main control valve to the pump have been changed from a combination of pipes and hoses to entirely hoses to minimise the risk of leakage. Instead of the resin (synflex), the hoses are now made from full rubber (Acryl nitrile butadiene).  This new material, combined with a new fitting, reduces bending and therefore ensures sound hydraulic flow, while reducing internal pressures.

It comes with a heavy duty undercarriage with three upper rollers compared to two on most of the competitive models. This is complemented by nine lower rollers and three track guards per track frame.

Easy going

A hydraulic excavator’s productivity revolves around its operator. With this in mind, the Doosan DX520LCA has several features focused at the operator.

The Electronic Power Optimising System (e-POS) said to be the brains of this machine, has been improved compared with its predecessor. It now comes with a Controller Area Network (CAN) communication link, which enables continuous exchange of information between the engine and the hydraulic system, perfectly synchronising the two crucial components.

Through its various features, the new e-POS system guarantees ease of operation and user-friendliness. For example, an operational memory provides a graphic display of the status of the machine, while its automatic deceleration mode also means better fuel saving.

A new user-friendly LCD monitor panel gives the operator full access to machine settings and maintenance-related data. “The control panel is very clear, simple to read and positioned for easy use,” says Whitehead.  The PC monitoring function enables connection to the e-POS system. Thus, various parameters, including pump pressures, engine rotation and engine speed, can be checked during maintenance.

Meanwhile, easily accessible service points ensure easy serviceability. Access to various radiators is very easy, making cleaning of these components simpler. Engine parts can be easily reached via the top and side panels. For easy maintenance, the boom and arm’s greasing points have been centralised.[/vc_column_text]