Caterpillar’s D9G, which was first introduced in 1961, is probably the most famous bulldozer in the world, and my heart certainly has a soft spot for them, having watched the powerful beasts in action as a youngster back in the early 1970’s. However, there was also a number of special conversion models available back in the day, including the SxS D9G, which was essentially two D9G’s joined together side by side, with a massive 24 foot dozer blade up front. The other model was the DD9G, also known as the Quad-Nine, which was once again a double tractor configuration, only this time they were coupled together one behind the other.
These 770hp monsters were primarily designed to push load scrapers faster than had ever been achieved before. The dozer was the most powerful Caterpillar model available, until the introduction of the D10 in 1978, was controlled by one operator who was seated in the front tractor which was fitted with controls for both units. I think you will agree this is awesome footage, and just listen to the growl of those big Cat engines as they power up into the push!