Diesel engines and HCCI
Diesel Ignition Process
Diesel engines and HCCI (Homogeneous charge compression ignition) engines, rely solely on heat and pressure created by the engine in its compression process for ignition. The compression level that occurs is usually twice or more than a gasoline engine. Diesel engines take in air only, and shortly before peak compression, spray a small quantity of diesel fuel into the cylinder via a fuel injector that allows the fuel to instantly ignite. HCCI type engines take in both air and fuel, but continue to rely on an unaided auto-combustion process, due to higher pressures and heat. This is also why diesel and HCCI engines are more susceptible to cold-starting issues, although they run just as well in cold weather once started. Light duty diesel engines with indirect injection in automobiles and light trucks employ glowplugs (or other pre-heating: see Cummins ISB#6BT) that pre-heat the combustion chamber just before starting to reduce no-start conditions in cold weather. Most diesels also have a battery and charging system; nevertheless, this system is secondary and is added by manufacturers as a luxury for the ease of starting, turning fuel on and off (which can also be done via a switch or mechanical apparatus), and for running auxiliary electrical components and accessories. Most new engines rely on electrical and electronic engine control units (ECU) that also adjust the combustion process to increase efficiency and reduce emissions.
Is it worth it to celebrate the day without a car?
In particular, many major urban centers there is more and more a problem with the huge traffic jams, especially during rush hours, which is why the authorities of many cities persuade motorists to give up to move your own vehicle and elected public means of transport. Although using public transport for sure we are exposed to the crowd on trams or buses, it should be induced to such exchange. True, motoring fans argue that the use of own car is much more comfortable, but we must bear in mind also that choosing the bus instead of the car contribute to fewer exhaust emissions.
Surfaces in contact and relative motion
Diagram of an engine using pressurized lubrication
Wikimedia Commons has media related to Internal combustion piston engine lubrication systems.
Surfaces in contact and relative motion to other surfaces require lubrication to reduce wear, noise and increase efficiency by reducing the power wasting in overcoming friction, or to make the mechanism work at all. At the very least, an engine requires lubrication in the following parts:
Between pistons and cylinders
Big end bearings
Valve gear (The following elements may not be present):
Timing chain or gears. Toothed belts do not require lubrication.