diesel locomotive models

The EGR system routes a number of the exhaust gases (6 ? 10%) through the EGR valve, back in for the Intake System, and finally inside combustion chamber. The exhaust gases are inert i.e. they do not burn inside the combustion chamber; also, the exhaust gases occupy a few of the space which may otherwise be taken from the intake air. This cuts down on level of intake air readily available for the combustion process during each Power Stroke; which often decreases the peak combustion temperatures. This ends in lower NOx emissions. For wild animals, showing teeth doesn't imply smiles on the camera and photographers. The only reason for their exposing teeth is because face-up with brutal situation leading to battles for food, dating mate and territory. These fightings are always very intense but it shows how nature occasionally works and indicates view of cruel life.