Sri Ram, I'm actually a field mechanic for a gas field construction company, we build all the roads and locations for the drilling rigs, as well as do reclamation work. In the picture I posted, my truck is sitting on a recently pioneered road, still not finished (dozer broke before he could finish it).
So I'm not a Cat- employed field mechanic, but we have mostly all Cat equipment, around 30 dozers, including D7's, D8's and D9's, as well as 14 cat motor graders, 8 cat front end loaders, about 20 cat hoes (and a couple john deere's) a cat scraper, a cat articulated truck, and a couple john deere backhoes, and some other miscellaneous equipment (as well as dump trucks and lowboys).
So we're not near as big as some companies, but a lot bigger than we used to be.
In addition to our 3 service trucks and one "oil changer" truck, we have a Cat field mechanic assigned to us. Most Cat mechanics I know are pretty good, I have a buddy that works for Cat, but in the truck shop.
If you like working with your hands, and a new challenge every day, I'd say go for it! Of course there's always the downsides of working in mud, snow, dust storms, heat, etc, but it's fun.
And we wear blue coveralls.
Sorry for the long post...