How a car's engine is being lubricated:- Dry and wet sump

                             A dry sump is a lubricating oil management method for four-stroke and large two-stroke piston internal combustion engines that uses the secondary external reservoir for oil, as compared to a conventional wet sump system. Four stroke engines are lubricated by oil which is pumped into the various bearing and thereafter allowed to drain to the base of the engine. In most production cars, which use a wet sump system, this oil is simply collected in a three to the seven-liter capacity pan at the base of the engine, known as the oil sump, where it is pumped back up to the bearings by the oil pump, internal to the engine. In a dry sump, the oil still falls to the base of the engine, but rather than being collected into an oil sump, it is pumped into another reservoir by one or more scavenger pumps, run by a belt from the front or back of the crankshaft. Oil is then pumped from this reservoir to the bearings of the engine by the pressure pump. Typical dry pump systems have the pressure pump and scavenger pumps stacked up, so that one pulley at the front of the system can run as many pumps as desired, just by adding another to the back of the stack.



                               A dry sump offers many advantages, namely increased oil capacity and a lower center of gravity for the engine. Because the reservoir is external, the oil sump can be much smaller is a dry sump system, allowing the engine to be placed lower in the vehicle, in addition, the external reservoir can be as large as desired, whereas a larger oil sump raises the engine even further. Increased oil capacity by using a larger external reservoir leads to cooler oil. Furthermore, dry sump design is not susceptible to the oil starvation problems wet systems suffer from if the oil sloshes in the oil sump, temporarily uncovering the oil pump pickup tube. Having the pumps external to the engine allows them to be maintained or replaced more easily, as well. Dry sumps are common on larger diesel engines such as those used for ship propulsion. Many racing cars, sports cars, and aerobatic aircraft also utilize dry sump equipped engines because they prevent oil starvation at high loads and because their lower center of gravity positively affects performance.

                                "Dry sump system is used in situations where the vehicle has to change its position continuously like air crafts. The main advantage of this system in that there is no chance of breakdown. The oil supply during the up and down movement of the vehicle."


                                On the other hand, dry sump systems add cost and complexity, and the extra pumps and lines require more oil, so maintenance costs go up as well. A wet sump is a lubricating oil management design for four-stroke piston internal combustion engines which uses a built-in reservoir for oil, as opposed to an external or secondary reservoir used in a dry sump design. A wet sump offers the advantage of a simple design, using a single pump and no external reservoir. Since the sump is internal, there is no need for hoses or tubes connecting the engine to an external sump which may leak. An internal oil pump is generally more difficult to replace, but that depends on the engine design. Four stroke engines are lubricated by oil which is pumped into various bearings and thereafter allowed to drain to the base of the engine. In most production cars and motorcycles, which use a wet sump system, the oil is collected in a three to a seven-liter capacity sump at the base of the engine, where it is pumped back up to bearings by the oil pump, internal to the engine.


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