The Caterpillar D6D crawler tractor was introduced in 1977 in the USA, Japan, and Brazil. Production began in Scotland the following year. It was the replacement for the D6C.

[edit] Features

The D6D has a 3306T six-cylinder engine producing 140 flywheel horsepower (FWHP). It comes standard with oil-cooled brakes and clutches.

All units manufactured in the USA, Japan, and Scotland came standard with roll over protection adaptability and sealed and lubricated tracks.

All units manufactured in the USA came standard with sound suppression and an electric hour meter.

All units manufactured in Brazil came standard with combined steering clutches and brakes, as well as a hydraulic system.

[edit] Configurations

It is available in two configurations: the standard model has a track gauge of 74 inches (188 cm); the Low Ground Pressure (LGP) configuration has an 83-inch (211-cm) track gauge. Both configurations are available with direct drive or powershift transmission.

Standard configuration, direct drive tractors were manufactured in the USA, with a 03X or 05X serial number prefix; in Japan, with a 30X prefix; in Brazil, with a 74W prefix; and in Scotland, with a 19X or 01Y prefix. The 05X and 01Y units were only equipped with 125 FWHP.

Standard configuration, powershift tractors were manufactured in the USA, with a 04X prefix; in Japan, with a 31X prefix; in Brazil, with a 75W prefix; and in Scotland, with a 20X prefix.

LGP configuration, direct drive tractors were only manufactured in Japan, with a 32X prefix.

LGP configuration, powershift tractors were manufactured in the USA, with a 06X prefix, and in Japan, with a 33X prefix.

[edit] Modifications

In 1978, Caterpillar made a standardized fuel system water separator and added it to all the American units, beginning with 03X00634, 04X02844, 05X00543, and 06X00515.

In 1980 and 1981, Caterpillar installed new 3006 direct injection engines to all the Japanese and Scottish units, beginning with 30X02070, 31X01397, 32X01181, 33X00410, 01Y00460, 19X00766, and 20X03041. At the same time, all Japanese units also received an interim scroll fuel system.

Also in 1980 and 1981, Caterpillar introduced a neutral start standard to many of the American and Scottish units, beginning with 01Y00460, 19X00678, 03X00993, and 05X00841.

Again 1980 and 1981, Caterpillar introduced a scroll metering fuel system to many of the American and Scottish units, beginning with 19X00766, 20X03041, 03X01009, 04X06608, 05X00853, and 06X01115.

In 1984, Caterpillar made a standardized folded core radiator and added it to many of the American units, beginning with 03X01187, 04X09182, and 05X01138.

Production of the 03X ended in 1985. The 04X, 06X, 33X, 19X, and 20X ended production in 1986. The 01Y ended in 1987.

Meanwhile, between 1981 and 1985, the American 05X unit received numerous upgrades. A fifth reverse gear was added, beginning with 05X1009, a standardized blower fan was installed, beginning with 05X01076, and its horsepower was increased to 140 FWHP, beginning with 05X1138. In 1985, its tractor mainframe and roller frame were extended; it also received variable flow hydraulics, a halogen daylight extended lighting system, extended fuel range capacity, and improved cab features, beginning with 05X01255.

Two new units were introduced in 1985. The new Japanese unit was given a 6HC prefix; it is an LGP tractor with five forward and five reverse speeds, and 155 FWHP. It was specially designed for forestry applications. The new Brazilian unit was given a 19B prefix; it is a standard tractor that came standard with sealed and lubricated tracks and rollover protection system (ROPS) adaptability.

In 1992, another new unit was introduced in Brazil. It is a standard powershift unit with 155 FWHP. It has a 9FK prefix.

Production of the 05X ended in 1990. The 19B ended production in 1991. The 74W and 75W ended in 1992. The 30X ended in 1994. The 31X ended in 1996.

Based on data from the sales database of Ritchie Bros. Auctioneers, it is estimated that more than 48,800 Caterpillar D6D crawler tractors have been produced.

Highest Serial #

Brazil
19B	N/A
74W	01549
75W	04585
9FK	05345
Japan
30X	03462
31X	04746
32X	03123
33X	00851
6HC	03632
Scotland
01Y	00506
19X	00818
20X	04973
USA
03X	01210
04X	10626
05X	01347
06X	02103
Total = 48,876