Caterpillar has launched its new line of medium-size excavators that promises customers increased reliability, versatility, performance, and comfort, combined with lower owning and operating costs.

The new D series meets the latest European Union emission and sound regulations, says a company spokesman.
It includes:
•  The 320D – a standard 21.5-tonne excavator that is well suited for rental as well as utility, water and sewage and other construction applications;
•  320D RR – a 23 to 24-tonne machine that replaces the 320C L Utility. With a turning radius between the standard 320D and compact radius 321D, it is well suited for utility, and water and sewage applications;
•  321C compact radius, which will move to D series during late 2006 with an ACERT engine. It is suited for the same segments as the 320D RR and is a perfect machine for jobs that need to be done in tight urban environments;
•  The 35-tonne 328D CR, which is similar to 321D CR but with a 325D size upper frame and a 330D undercarriage for increased lifting capacity;
•  The 23.5-tonne heavy-duty 323D excavator with reinforced booms and sticks, which is also equipped with heavy-duty rollers and a heavier counterweight. It has a long undercarriage (L) as standard but can also be equipped with a long and narrow undercarriage (LN) or with 325D roller frames (S) for heavy-duty rock applications and is well suited for heavy construction and heavy-duty work;
•  The 25-tonne 324D is suited for utility and normal excavating applications as well as applications mandating productivity and a well-balanced machine. With increased lifting capacity, it is well placed for sewage and water applications;
•  The 28-tonne 325D, is well suited for high production truck loading, demolition and material handling work, and can be equipped with a ‘heavy-duty, high and wide’ undercarriage option for increased stability, lifting capacity and visibility; and
•  The ‘heavy-duty, high and wide’ undercarriage option is also available for the 34 to 37-tonne 330D. In addition, the 330D can be outfitted with the 345C undercarriage for extreme service. With the extreme service undercarriage, the 330D forms an excellent machine for rock and quarry applications, and feeding mobile crushers, says the spokesman.

Increased pressure
“Increased pressure gives the D series excavators best-in-class lifting capacity and more drawbar pull and digging force, thereby enhancing productivity,” he says. “The standard lifting capacity is improved by five per cent compared to the C-series with a pressure increase from 34.3 to 35 Mpa. In addition, a new heavy lift mode offers four per cent more capacity than the standard mode.
“Bucket digging force has been improved by six per cent. Stick digging force has been improved by seven per cent, due to increased pressure, because of re-designed bucket linkage geometry. The system is designed with an AccuGrade ready option, which makes levelling easy and fast even for inexperienced operators, increasing productivity and efficiency while facilitating site management. Drawbar pull has been enhanced by two per cent allowing the machine to spot turn and climb slopes more easily.”

Change tool, change job
Tool control in the D series has been improved by allowing the hydraulic system to handle up to 10 hydro mechanical tools compared to five in the C-series models. A shortcut button to tool selection menu makes use of work tools even easier, he says.
A universal Quick Coupler circuit accepts all hydraulic quick coupler systems and includes various pressures from 150 bar to full machine pressure 350 bar. Additional auxiliary hydraulic circuits are available for different customer requirements and can be retrofit.
The new VA boom features six per cent more lift and stability over front and three per cent over side. For enhanced reach, the fore boom length has been increased from 34 to 60 cm.

Enhanced operator station
D series medium-size hydraulic excavators are equipped with the same comfortable operator station as the Caterpillar C-series large hydraulic excavators that provides greater viewing area and superior sight lines to the work area.
The cab is quiet and features ergonomic control placement and convenient adjustments that allow the operator to fit the machine comfortably.
“The monitor in the cab displays a variety of understandable and easy-to-read information about machine functions. It features a full graphic video ready colour display with multiple language display capabilities. The monitoring system alerts the operator to machine health warnings and automatically provides maintenance information to the operator. At start-up, the system automatically checks important machine fluid levels, such as hydraulic oil, engine oil and engine coolant and provides immediate feedback to the operator,” he adds.