Caterpillar introduces new track-type tractor to replace the D6G and the D7G 
(21/01/2008)
Caterpillar has introduced new track-type tractor models D6G Series 2 XL and D7G Series 2, replacing the D6G and the D7G. Both models have been designed to provide companies in Africa and the Middle East with proven, robust machines that are simple to use and service. The high reliability and performance are guaranteed by the Cat® 3306 engine and the proven Cat designed and manufactured power train and undercarriage.
The D6G Series 2 XL and the D7G Series 2 tractors are an ideal choice for multiple industry applications ranging from general construction to forestry and agriculture. In forestry the D6G Series 2 is particularly suited for access road construction and maintenance, re-forestation, land clearing and light harvesting and the D7G Series 2 for building, logging roads building and pulling logs. Both machines are well-matched for residential, commercial and industrial building sites as well as for site preparation in landscaping and land improvement in the agricultural applications. In addition the D7G Series 2 is an excellent choice for landfill construction and maintenance.
The D6G Series 2 XL and the D7G Series 2 track-type tractors are powered by the 3306 direct injection turbocharged engines with 10.5-litre (638 in3) displacement. In the D7G Series 2 the engine is also aftercooled. These six-cylinder, four-stroke diesel engines deliver 119 net flywheel kW (160 net flywheel hp) at 1,900 rpm in the D6G Series 2 XL and 150 net flywheel kW (202 net flywheel hp) at 2,000 rpm in the D7G2. The large displacements allow lower engine speeds for reduced stresses and increased engine life.
The 3306 engine delivers a 24 percent net torque rise in the D6G Series 2 XL and an 18 percent net torque rise in the D7G2 for excellent lugging capabilities without down shifting under tough loading conditions.
The 3306 engine maintains good productivity per unit of fuel burned by using direct injection to control fuel consumption. The 3306 provides optimum weight-to-horsepower ratio to minimize cycle times, allow larger blade loads and shorten blade load times.
The 3306 engine is designed for easy maintenance and can be rebuilt for a second life. Caterpillar remanufactured parts are available to economically replace many components.
The 3306 engine is directly attached to a Caterpillar single stage torque converter with output torque divider combining smoothness with economy. An oil-to-water cooler cools the torque converter oil with full-flow filtered oil.
The torque divider arrangement is a Caterpillar exclusive that provides high torque multiplication when under load with direct drive efficiency when completing lower engine load functions such as backfilling trenches or spreading material. The torque divider transmits 70 percent of the engine torque through the converter and 30 percent via a planetary gear set connected to the output shaft.
The torque divider provides parallel power paths to combine the advantages of converter and direct paths. This means the operator gets the broader load handling capabilities of converter drive plus an increase in peak drive efficiency due to power flowing directly to the transmission without significant increases in dynamic torques.
The power shift transmission uses 381 mm large-diameter, high-capacity, oil-cooled clutches for smooth automatic shifting. Oil is forced through the clutch packs to provide optimum cooling and maximum clutch life and the oil-to-water cooling provides maximum cooling capacity and reliability.
Quick, smooth speed and directional changes are achieved through a special valve that modulates oil flow to the clutches. The result is a single manufacturer design of key power train components in the diesel engine, torque divider and power shift transmission. This ensures compatibility of components that deliver power for a variety of conditions and applications.
To maximise the long component life to guarantee high performance, the track roller frame both in the D6G Series 2 XL and in the D7G Series 2 is a reinforced box section construction with lifetime-lubricated rollers. D6G Series 2 XL features seven track rollers (XL) as standard and two outside mounted carrier rollers feature per side. D7G2 features six track rollers.
Track roller frames oscillate to provide operator comfort when working on uneven underfoot conditions. Idlers have two adjustable positions and are also lifetime-lubricated. Standard track is the 560 mm moderate service single grouser shoe with optional 610 mm and 510 mm single grouser shoes available.
Standard tracks feature the sealed and lubricated links and eliminate internal bushing wear as a maintenance consideration by surrounding the track pin with a lubricant. Track links are “strutted” for added durability against breakage. Two piece-master links for easy track removal is standard. This provides reduced downtime when changing or maintenance on undercarriage is being completed.
As in all Caterpillar machines, special attention has been paid to a comfortable operator station. In the D6G Series 2 XL and in the D7G Series 2 the cab provides excellent viewing area to the blade and rear of the machine for maximum productivity and safety. To increase operator efficiency, the foot brake and decelerator pedals are suspended.
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