Wet sump
Encyclopedia
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.
Four-stroke engines are lubricated by oil which is pumped into various bearing
s, and thereafter allowed to drain to the base of the engine under gravity. In most production automobile
s and motorcycles, which use a wet sump system, the oil is collected in a 3 litre capacity pan at the base of the engine, known as the sump
or oil pan, where it is pumped back up to the bearings by the oil pump
, internal to the engine.
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 is dependent on the engine design.
A wet sump design can be problematic in a racing car, as the large g force
pulled by drivers going around corners causes the oil in the pan to slosh, gravitating away from the oil pick-up, briefly starving the system of oil and damaging the engine. However, on a motorcycle this difficulty does not arise, as a bike leans into corners and the oil is not displaced sideways. Nevertheless, racing motorcycles usually benefit from dry sump
lubrication, as this allows the engine to be mounted lower in the frame; and a remote oil tank can permit better lubricant cooling.
Early stationary engine
s employed a small scoop on the extremity of the crankshaft
or connecting rod
to assist with the lubrication
of the cylinder
walls by means of a splash
ing action. Modern small engines, such as those used in lawnmowers, use a "slinger" (basically a paddle wheel) to perform the same function.
Motor oil
Motor oil or engine oil is an oil used for lubrication of various internal combustion engines. The main function is to lubricate moving parts; it also cleans, inhibits corrosion, improves sealing, and cools the engine by carrying heat away from moving parts.Motor oils are derived from...
management design for four-stroke
Four-stroke cycle
A four-stroke engine, also known as four-cycle, is an internal combustion engine in which the piston completes four separate strokes—intake, compression, power, and exhaust—during two separate revolutions of the engine's crankshaft, and one single thermodynamic cycle.There are two...
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
Dry sump
A dry sump is a lubricating motor oil management method for four-stroke and large two-stroke piston internal combustion engines that uses external pumps and a secondary external reservoir for oil, as compared to a conventional wet sump system....
design.
Four-stroke engines are lubricated by oil which is pumped into various bearing
Bearing (mechanical)
A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...
s, and thereafter allowed to drain to the base of the engine under gravity. In most production automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
s and motorcycles, which use a wet sump system, the oil is collected in a 3 litre capacity pan at the base of the engine, known as the sump
Sump
A sump is a low space that collects any often-undesirable liquids such as water or chemicals. A sump can also be an infiltration basin used to manage surface runoff water and recharge underground aquifers....
or oil pan, where it is pumped back up to the bearings by the oil pump
Oil pump (internal combustion engine)
The oil pump in an internal combustion engine circulates engine oil under pressure to the rotating bearings, the sliding pistons and the camshaft of the engine...
, internal to the engine.
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 is dependent on the engine design.
A wet sump design can be problematic in a racing car, as the large g force
G force
The g-force associated with an object is its acceleration relative to free-fall.It may also refer to:* G-Force , a 2009 film by Disney** G-Force , a 2009 video game based on the film...
pulled by drivers going around corners causes the oil in the pan to slosh, gravitating away from the oil pick-up, briefly starving the system of oil and damaging the engine. However, on a motorcycle this difficulty does not arise, as a bike leans into corners and the oil is not displaced sideways. Nevertheless, racing motorcycles usually benefit from dry sump
Dry sump
A dry sump is a lubricating motor oil management method for four-stroke and large two-stroke piston internal combustion engines that uses external pumps and a secondary external reservoir for oil, as compared to a conventional wet sump system....
lubrication, as this allows the engine to be mounted lower in the frame; and a remote oil tank can permit better lubricant cooling.
Early stationary engine
Stationary engine
A stationary engine is an engine whose framework does not move. It is normally used not to propel a vehicle but to drive a piece of immobile equipment such as a pump or power tool. They may be powered by steam; or oil-burning or internal combustion engines....
s employed a small scoop on the extremity of the crankshaft
Crankshaft
The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...
or connecting rod
Connecting rod
In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion....
to assist with the lubrication
Lubrication
Lubrication is the process, or technique employed to reduce wear of one or both surfaces in close proximity, and moving relative to each another, by interposing a substance called lubricant between the surfaces to carry or to help carry the load between the opposing surfaces. The interposed...
of the cylinder
Cylinder (engine)
A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...
walls by means of a splash
Splash
Splash may refer to:* Splash , sudden disturbances on the surface of water* Splash, in erosion, is the detachment and airborne movement of small soil particles caused by the impact of raindrops on soils-Computing:...
ing action. Modern small engines, such as those used in lawnmowers, use a "slinger" (basically a paddle wheel) to perform the same function.