The VanNatta's don't keep one of these beauties around 'cause they tend to be priced even in the second hand market at over half a million dollars US. They are something to behold however, bigger and stronger that the Fiat Allis 31.
This model weighs in at around 140,000 lbs and features over 500 horsepower. It is not the largest dozer around, as there is a 750 horsepower class as well, but the D10 is still a serious dozer. Dozers of this size haven't been around all that long (perhaps 20 years) but they are very productive. This compares to the D9 class machine (the next size smaller) which has been around since the late 1950's. Cat was not the first out with a over 500 horsepower machine--the credit for that goes to Fiat Allis with their FA 41 (big brother to the FA 31 featured on another page, but Fiat Allis is out of the giant tractor market, and Cat is dominating it.
The enormous cost and logistical problems in moving these machines limits their usefulness to major mining operations, but there they shine. this lower picture shows a machine partially disassembled for moving. The ripper and the blade are both off of it. Removal of these items it not technically difficult as the blade bolts on with only a few bolts, and the ripper pins on with a few pins and some hydraulic hoses, but the sheer mass size of the pieces makes it a challenge and requires that a substantial crane be available at the assembly site.
Viewed here is a different machine which presents a particularly good view of the ripper. It is of a 4 barrel type with 2 cylinders to lift the ripper and the upper 2 cylinders to adjust the angle of attack. It is a single tooth ripper. Notice the little 'shelf' on the back of the ripper. This is a 'push pad' in that you can set the blade of a second dozer on this pad and the weight of the blade will assist holding the ripper down in the ground as well as provide a place to push forward.
The Cat D10N, of course, is no longer the latest and greatest. Cat now has the "R" series which in keeping with tradition is a little larger, and a little more productive. One of the things that I am really fascinated about is what Cat is going to do for model numbers when the alphabet runs out. their number models have been around for so long (sixty years or so) that abandoning them would be a big loss. Accordingly for the last 25 years or so whenever they made a revision of the product, they have just incremented the letter designation following the number. For a while different models had a different number of revisions, so for example the D6C, D8H and D9G were all made at the same time. More recently however, they have adopted a uniform letter series, so dozers with the "R" on the end are a family of dozers introduced over a period of a few years in the late 1990's.