Hi ! Can someone tell me what the "H" stands for in the HD 21 Allis-Chalmer ??? also anyone knows what the "T" would stand for TD25 International ?? regards
As far as I know the T in TD stands for "Tractor" and when when they later beame available with diesels the D was for "Diesel". In case of Allis Chalmer, I´m not so sure though.
Same for the "D" in today's Cat machines. The old gas burners of the early 20th Century were known as Caterpillar 20s or 60s............with the intro of diesel engines the designations became "D-2" or "D-6" signifying the diesel engine vs. the previous gas engines in the same machines. I always assumed, just on my own, that the "HD" in AC's line was probably a reference to "heavy duty" or "heavy, diesel" but that's just my own mind wondering. Agree about IH.......TD........is internal nomenclature for "tractor, diesel" in their language. Komatsu adopted so much of the Caterpillar methodology in it's infancy that I believe they simply used the "D-" designator since it was so common and well known around the world for labeling and sizing tracked machines.
International system was track diesel (TD), they offered numerous products back then, often using the same engine in various forms WD wheel diesel, rubber tire tractor UD utility diesel, graders, air compressors, etc where a prime mover was req PD power diesel, gensets
Hi ! Thank you to all who replied , it is been useful