Caterpillar D4

rdf:langString Caterpillar D4

rdf:langString The Caterpillar D4 track-type tractor is a small bulldozer manufactured by Caterpillar Inc. Caterpillar first introduced the RD4 in 1936 as the diesel follow on to the successful CAT 30 gas model. The RD4 originally weighed in at 10,000 pounds (4,500 kg), and used Caterpillar's D4400 engine, an inline four-cylinders, with a 4.25 by 5.50 inches (108 mm × 140 mm) bore and stroke. In 1935 Caterpillar had started the naming convention of "RD" for diesel or "R" for regular gasoline, followed by a number to indicate the relative engine size. In 1937 the "R" was dropped, and just a "D" was used for the diesel versions. At the time of introduction of the RD4, the D4400 engine produced about 43 horsepower (32 kW) at the drawbar so the 4 indicated the relative engine power. The D4 U series was fitted with the more powerful D315 engine. The later D4 series engines quickly increased in power, so the number "4" just became a figure of merit rather than indicating actual engine power.