Two new crawlers recently added to Doosan Infracore’s lineup were featured as part of the company’s participation at ConExpo 2008. The new models—DX225 and DX255—feature an electronically optimized hydraulic system, next-generation Doosan engine, improved ergonomics and visibility, and reduced maintenance.
The new six-cylinder Doosan DL06 common-rail diesel engine delivers 148 hp (110 kW) for the DX225 and 166 hp (124 kW) for the DX255, both at 1900 rpm. Maximum torque is available from 1400 rpm: 667 N·m (492 lb·ft) for the DX225, and 765 N·m (564 lb·ft) for the DX255. Controlled by the company’s e-EPOS (electronic power optimizing system) electronic control system, the U.S. EPA Tier-3-certified engine is direct-injected, and turbocharged with an air-to-air intercooler.
Also controlled by e-EPOS is the dozers’ hydraulic system. A data transfer link helps to harmonize the operation of hydraulics and the engine based on power demand and working conditions. The system enables independent or combined operation, an auto deceleration system, a cross-sensing pump system for reduced fuel consumption, and two travel speeds, one for higher torque and the other for high speed tracking. The system also offers two operating modes—digging mode for excavation, loading, and digging, and trenching mode with priority to the swing for trenching and digging. There are also two power modes—standard, which uses 85% of engine power for all work, and power, which uses 100% engine power for heavy work.
The DX225 and DX255 dozers deliver a claimed bucket digging force of 33,510 lb (149 kN) and 35,494 lb (158 kN), respectively, and an arm digging force of 27,778 lb (124 kN) and 26,676 lb (119 kN), respectively. Booms measure 5.7 m (18.7 ft) for the DX225 and 5.9 m (19.3 ft) for the DX255, while arms measure 2.9 m (9.5 ft) for the DX225 and 3.0 m (9.8 ft) for the DX255. Bucket capacities are 0.92 m3 (1.2 yd3) for the DX225 and 1.1 m3 (1.44 yd3) for the DX255.
Designed for durability, the DX225’s undercarriage features two upper and nine lower rollers plus 49 track shoes per side, with a total track length of 4.44 m (14.58 ft). The DX255’s undercarriage has two upper and 10 lower rollers plus 51 track shoes per side, with a total track length of 4.63 m (15.17 ft). For both dozers, the undercarriage features an X-chassis section that was designed using finite-element analysis and 3-D computer simulation, as well as a D-type frame and chassis frame that add strength and minimize shock-induced distortions.
Each track is driven by an independent axial-piston motor through a planetary reduction gearbox. Two levers with control pedals provide smooth travel with counter-rotation on demand. Track chains feature self-lubricating sealed links for isolation from external contamination.
Operator performance is supported by the dozers’ cab, with comfort features including an adjustable suspension seat that slides to two positions; control stand with telescopic function; and high-performance air-conditioning. The cab is sound-suppressed and mounted on viscous mounts that help to reduce noise and vibration. Other cab features include a sunroof, LCD color monitor panel, radio, hot/cool storage box, and an optional air-suspension seat with lumbar support and seat warmer.