Within

piston engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common feat ...

s, a wet sump is part of a

lubrication Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces. The study of lubrication is a discipline in the field of tribology. Lubrication mechanisms such as fluid-lubric ...

system whereby the

crankcase In a piston engine, the crankcase is the housing that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block. Two-stroke engines typically use a crankcase-compression design, resulting in the fuel ...

sump A sump is a low space that collects 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. Sump can also refer to an area in a cave ...

is used as an integral oil reservoir. An alternative system is the dry sump, whereby oil is pumped from a shallow sump into an external reservoir.Wet sump and dry sump compared - https://www.knowyourparts.com/technical-resources/engine/oil-system-differences/#:~:text=Dry%20Oil%20Systems%20Wet%20sump%20systems%20store%20the,is%20used%20to%20pump%20oil%20from%20the%20motor. Piston engines are lubricated by oil which is pumped into various bearings, and thereafter allowed to drain to the base of the engine under gravity. In most production

automobile A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods. The year 1886 is regarded ...

s and

motorcycles A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...

, which use a wet sump system, the oil is collected in a capacity pan at the base of the engine, known as the

or oil pan, where it is pumped back up to the bearings by the internal oil pump. 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 the shallow sump allows the engine to be mounted lower in the frame; and a remote oil tank can enables improved lubricant cooling. On some dry sump motorcycles, such as the Yamaha TRX850 and the Yamaha TDM, the oil tank is integral to the engine, sitting atop the gearbox. Early

stationary engine A stationary engine is an engine whose framework does not move. They are used to drive immobile equipment, such as pumps, generators, mills or factory machinery, or cable cars. The term usually refers to large immobile reciprocating engines, ...

s employed a small

scoop Scoop, Scoops or The scoop may refer to: Objects * Scoop (tool), a shovel-like tool, particularly one deep and curved, used in digging * Scoop (machine part), a component of machinery to carry things * Scoop stretcher, a device used for casualt ...

on the extremity of the

crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecti ...

connecting rod A connecting rod, also called a 'con rod', is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the crank ...

to assist with the

of the

cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an ...

walls by means of a splashing action. Modern small engines, such as those used in lawnmowers, use a "slinger" (basically a paddle wheel) to perform the same function.

Two-stroke and four-stroke engines

Small

two-stroke engine A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of ...

s, such as in

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle Steering, steered by a Motorcycle handlebar, handlebar. Motorcycle design varies greatly to suit a range of different purposes: Long-distance ...

s and

lawnmower A lawn mower (also known as a mower, grass cutter or lawnmower) is a device utilizing one or more revolving blades (or a reel) to cut a grass surface to an even height. The height of the cut grass may be fixed by the design of the mower, but g ...

s, have total loss lubrication. Such engines use crankcase compression to feed the fuel/air mixture through the crankcase. This precludes the use of both wet sump and dry sump systems, as excess oil here would contaminate the mixture, leading to excess oil being burned in the engine and so excessive

hydrocarbon emissions In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...

. These small engines run on specifically prepared fuel, a mixture of gasoline and

two-stroke oil Two-stroke oil (also referred to as two-cycle oil, 2-cycle oil, 2T oil, or 2-stroke oil) is a special type of motor oil intended for use in crankcase compression two-stroke engines, typical of small gasoline-powered engines. Use Unlike a four ...

in a ratio recommended by the manufacturer. In some engines this mixture may also be independently pre-injected into the engine cylinders and bearings by a pump.

Four-stroke engine A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directi ...

s and large (non-petrol) two-stroke engines used in locomotives and

ships A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished ...

may have either wet or dry sumps. Large two-stroke engines do not use crankcase compression; instead they use a mechanical blower or a

turbocharger In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pro ...

to aspirate air.

Types of Wet Sump

* The Splash System * The Splash and Pressure System * The full Pressure Feed System

References

{{Automotive engine Engine lubrication systems