Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/335762
chine Control provide improve- ments in dozing efficiency of 9 and 13 percent, respectively. This is achieved through automatic control of the blade during both rough and finish dozing com- bined with minimizing track slip by monitoring blade load. Both models have three user- selectable load settings plus four dozing modes to tailor machine performance to the application: cut, cut and carry, spreading and simple grading. All directional movements and the dual-path hydrostatic transmissions are con- trolled with Komatsu's Palm Com- mand Control System joystick. Komatsu builds the D51i-22 with a Tier 3 engine while the D61i-23 has a Tier 4 Interim en- gine with DPF aftertreatment. All Komatsu models come standard with KOMTRAX machine monitor- ing system. Additionally Tier 4 In- terim models come with Komatsu Care complimentary maintenance. Liebherr The PR 736 (201 horsepower) will soon replace the PR 734. Tier 4 Final compliance is achieved with the use of an SCR. According to Robert Klima, Liebherr's product manager of crawler tractors, SCR has lower operating costs than using a DPF, is simpler to main- tain, and does not require the regeneration cycle of DPF sys- tems. While SCR requires the use of DEF, topping off the DEF tank typically occurs during refueling. With a displacement of 7.0 liters, the inline 4-cylinder en- gine on the PR 736 is larger than many inline 6-cylinders engines found in other dozers of this size. The intent is to provide excellent power and performance along with gains in fuel efficiency. In heavy dozing applications, the PR 736 has an up to 6 percent increase in fuel efficiency over the PR 734. Even greater fuel savings can be had under light and medium loads when using the ECO mode. The hydrostatic travel pumps and motors are car- ried over from the PR 734 but the electronic controls are all new. Liebherr chose to develop their machine control system entirely in-house. As with other machine control systems, the one on the PR 736 manages engine power and varies hydraulic pump and motor parameters to provide op- timal performance based on load conditions. A seat switch replaces the safe- ty levers of previous designs. A delay allows the operator to rise and check the blade while the dozer continues to operate nor- mally. Once in safety mode the machine can idle but all hydraulic circuits are inactive. Like all Liebherr Generation 6 dozers, the PR 736 is compatible with blade control systems from all major suppliers and can be or- dered GNSS-ready for the system of the customer's choosing. July 2014 | EquipmentWorld.com 38 machine matters | continued Liebherr's 201-horsepower Generation 6 PR736 will replace the com- pany's PR734 and uses a 4-cylinder inline engine offering a 6 percent increase in fuel effi ciency over the previous model.