While EPA’s Tier 3 emissions requirements were the primary driver for Caterpillar’s newest generation of mid-size, D-Series excavators, the company didn’t limit its improvements to a cleaner engine system.
Using the C-Series excavators as a starting point, engineers spent a portion of their resources meeting the emission rules that took effect this year for 175- to 300-horsepower engines, then used what was left over to work on solutions to customers’ concerns about productivity and real world working conditions. The result is an excavator that addresses escalating operating costs and the shortage of qualified labor, says Mark McClain, worldwide product manager for excavators.
Compared to their C-Series predecessors, the three D-Series excavators have more horsepower – up 12 percent for the 324D and 9 percent for the 325D and 330D – along with increased digging force, lifting capacity and cycle times. Caterpillar stepped up crowd forces for the D-Series 5 to 9 percent and curl forces 4 to 13 percent. “Operators can definitely feel that,” says Jason Bowers, who is responsible for D-Series marketing in North America. “In the end it means more dirt moved at the end of the day.”
A heavy lift circuit and lift eye improve lifting capacity 5 percent compared to the previous models and allow you to get the boom cylinder lower to the ground. Two additional track lengths offer more stability, and a longer stick gives you better reach and dig depth.
At the press of a button, Cat’s tool control system sets the optimum hydraulic flow and pressure for 10 attachments. The pre-programmed options include one-way or two-way flow, one or two pumps and high and medium pressure. The D-Series offers the ability to add tool control auxiliary hydraulics to the system through kits that can be installed in the field or at a dealer’s facility. For example, if you’ve been doing trenching work with one of the excavators for two years and then get a demolition job, you can install a more appropriate auxiliary hydraulic or attachment option in the field and it will work as if it were set up at the factory, Bowers says.
Engineers designed the excavators’ new pin-grabber coupler to help you control costs. “You can pick up more of the competitors’ buckets or more of the buckets you already own,” Bowers says. The coupler, which sports three redundant locking systems, allows you to use buckets in the front-shovel orientation for underground utility construction. Most operators can change attachments with the coupler in 35 seconds or less.
The first thing you’re likely to notice when you see a D-Series excavator is the Cat logo. It’s much larger than the logo on the C-Series machines and is prominently displayed in a black box on the back of the machines. Styling changes continue in the cab, where there’s a two-tone color scheme and an upgraded monitor that tracks major component hours and attachment use. The color screen offers 27 language choices, a quick pre-start check of vital fluid levels and machine diagnostics the operator can give a technician. With the D-Series, Caterpillar made the monitor easier to read and operate and improved navigation through the screens. “Our monitors are designed to interface with that operator, that owner and that technician through language,” says John Walker, senior sales and marketing consultant for Caterpillar’s Heavy Construction Division.
Caterpillar maintained the C-Series’ 500-hour engine service interval with its ACERT-technology Tier 3 engine. It also doubled the hydraulic return filter service interval to 2,000 hours. Other maintenance-focused features include color- and number-coded electric wires and connectors, and sample tabs for fast system checks.
