Numerous performance, comfort and reliability enhancements accompany interim Tier IV (iT4) compliance on the Doosan DL550 wheel loader, which replaces the DL500 loader model. Improvements ranging from more engine horsepower to increased driving power and steering capabilities highlight the 7.5-cu.-yd. (5.7 cu m) wheel loader.
The DL550 is the largest wheel loader in the Doosan line. With an operating weight of 69,655 lbs. (31,595 kg), breakout force of 58,450 lbs. and a full-turn tipping capacity of 48,061 lbs. (21,800 kg), the DL550 is designed for larger material handling applications, such as quarries, mines and manufacturing operations.
Power
The DL550 horsepower has been increased to 380 (283 kW) with a 6-cylinder diesel engine that has been optimized for use with selective catalyst reduction (SCR) and diesel exhaust fluid (DEF) to comply with iT4 emission regulations. Engines with this configuration are optimized to reduce particulate matter (PM) by operating at higher combustion temperatures and to reduce nitrogen oxides (NOX) with exhaust after-treatment using SCR technology. Additionally, SCR systems offer increased fuel efficiency due to the engine optimization, which improves fuel burn.
The 775-cu.-in. (12.7 L) engine features a high-pressure common-rail (HPCR) design with direct fuel injection, electronic control and four valves per cylinder. The high-pressure common-rail system increases the efficiency of fuel delivery by increasing the pressure up to 34,000 psi. The increased pressure allows the injector to inject a finer mist into the engine, which results in a more efficient combustion that in turn produces more torque and improved fuel economy, less noise, lower operating costs and cleaner exhaust, according to the manufacturer.
Performance
Designed with improved lifting performance, the DL550 offers operators the ability to set upper and lower limits for both the lift arm and bucket stop positions from inside the cab. This provides improved control of the lift arm and bucket positions and is particularly useful when setting return-to-dig positions for the lift arm and bucket, which reduces cycle times in digging and loading applications. This feature allows the DL550 to effectively move material overhead with a dump height of 11 ft. 2 in. (3.4 m).
The new automatic reversing cooling fan can be set to run in reverse to assist in keeping the cooling system clean. The operator can select to reverse the fan via a switch, or it can be set to automatically reverse on a preset time frame. Each time the fan reverses, it will run in reverse for few minutes to clean the cooling system. This helps in dirty and dusty conditions to keep the machine running at optimal performance, using less power to cool the machine. This results in longer working hours and shorter maintenance time to clean the cooling system.
This wheel loader’s new auto-idle feature provides additional noise reduction and fuel savings by reducing the working idle of the wheel loader from 950 rpm to a standby idle setting of 750 rpm when the machine is inactive for a short period of time.
The upgraded DL550 features a hydraulic locking differential available as an alternative to the standard limited slip differential. The hydraulic locking differential comes standard and provides increased driving power when one wheel spins or loses traction, allowing the machine to navigate tough terrain. The differential may be locked manually or automatically, based on ground conditions.
Another common option for the DL550 is a torque converter lockup clutch. This enables the machine to climb grades easier and faster, increasing productivity as much as 20 percent in certain stockpiling applications. For those requiring additional dumping capabilities, the DL550 also is available in a high- lift configuration.
Comfort
The DL550 is now equipped with optional electric steering to decrease operator fatigue during repetitive cycle operations on the job site. A joystick has been added to the left armrest that allows the operator to control the directional movement without having to use the steering wheel. A new door makes getting in and out of Doosan wheel loaders — and cleaning the inside of the cab — much easier. The air suspension seat with heat is offered standard on the DL550.
Interior cabin improvements also include a number of multi-function display panel upgrades on a centralized monitor that allows the operator to view comprehensive machine system information. The centralized monitor displays critical machine information — such as engine rpm, engine coolant temperature, fuel level, DEF level, machine warnings, time and the transmission selected gear. A key exterior cabin improvement is lowered front side glass, providing improved visibility of operations.
Reliability
More new options for Doosan wheel loaders include a diesel-powered coolant heater to improve starting in cold weather or a block heater that warms the engine coolant before engine startup with an electrical heater.
Service intervals on the front lift arm pins have increased from 50 to 250 hours, reducing operating costs and downtime. Tilt cylinder hydraulic hoses have been rerouted for improved hose reliability, better hose movement and improved visibility to the attachment.
The DL550 — like every new Doosan machine — is covered by a 48 hour parts guarantee. The program guarantees that if a “machine-debilitating” part is needed, Doosan will deliver it directly to the end user within two business days or Doosan will pay for a replacement machine rental. The 48 hour parts guarantee is subject to carrier delivery restrictions and/or governmental agency delays.
For more information, visit www.dosanequipment.com.
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