The Classic Machinery Network

i have seen photos of the twin d9 but never one working check it out at this link http://www.youtube.com/watch?v=9gAYeyUB7oA

Rare footage there good find.
Martyn

Two, but not dual, D9s pushing a Blackwell 657 in about 1966.

i think we are both wrong they where called Caterpillar Quad-Track D9G check this link out http://www.pbase.com/onetrack/caterpillar_technical

Think that they were known as Dual D9s during the Petersen prototype stage and were re named the DD9 when Cat bought the rights and made them as a factory option but were often refereed to as Quadtrack. I have a Cat spec sheet headed Caterpillar DD9H (Dual D9H)with no mention of Quadtrack anywhere!

The Peterson version was called the Peterson Quad-trac D9G. The Caterpillar version was called the D9G. They were quite the machine to work with. I never ran them but a company I worked for in the mid 80s still had two sets of them. I quit working there in 1993 & they still had them but they had split up both sets & made single push cats out of them.

OOPS. Cat called them the DD9G.

How do you think they steered? Looks like the front unit steers normally and the rear follows the line - just wondering if the rear steers too or if just directed by the front?

Dah wrote:How do you think they steered? Looks like the front unit steers normally and the rear follows the line - just wondering if the rear steers too or if just directed by the front?

I believe that there were two steering modes. For gentle turns the two left of right tracks were braked/clutched conventionally while for sharp manoeuvres the opposite tracks were braked/clutched diagonally so as to "jack-knife" the machines. However, never seen one in the metal !