Large transportation projects systems, like mass transit networks in cities, require quiet HVAC systems for comfort in the passenger environment. Additionally, the mass-transit coaches have severe cooling requirements within the traction and braking machinery in the DC drive system. These same traction motor systems are used in heavy- duty construction equipment and railway locomotive designs. Custom designed OEM fans by DECENT MACHINERY fill these requirements. Aircraft cooling and avionics cooling devices use DECENT MACHINERY Commercial Pressure Blowers to maintain critical temperatures for both commercial and military applications.