Splash lubrication is a rudimentary form of lubrication found in early engines. Such engines could be
external combustion engines (such as
stationary steam engine
Stationary steam engines are fixed steam engines used for pumping or driving mills and factories, and for power generation. They are distinct from locomotive engines used on railways, traction engines for heavy steam haulage on roads, steam c ...
s), or
internal combustion engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal co ...
s (such as petrol, diesel or paraffin engines).
Description
An engine that uses splash lubrication requires neither oil pump nor oil filter. Splash lubrication is an antique system whereby scoops on the
big-ends of the
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 cranksha ...
s dip into the oil
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 cav ...
and splash the lubricant upwards towards the cylinders, creating an
oil mist which settles into droplets. The oil droplets then pass through drillings to the bearings and thereby lubricate the moving parts. Provided that the bearing is a
ball bearing
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.
The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this ...
or a
roller bearing
In mechanical engineering, a rolling-element bearing, also known as a rolling bearing, is a bearing which carries a load by placing rolling elements (such as balls or rollers) between two concentric, grooved rings called races. The relative m ...
, splash lubrication would usually be sufficient; however,
plain bearing
A plain bearing, or more commonly sliding contact bearing and slide bearing (in railroading sometimes called a solid bearing, journal bearing, or friction bearing), is the simplest type of bearing, comprising just a bearing surface and no roll ...
s typically need a pressure feed to maintain the oil film, loss of which leads to overheating and seizure.
The splash lubrication system has simplicity, reliability, and cheapness within its virtues. However, splash lubrication can work only on very low-revving engines, as otherwise the sump oil would become a frothy mousse. The Norwegian firm,
Sabb Motor
Sabb Motor is a Norwegian maker of small marine diesel engines, mostly single-cylinder or twin-cylinder units. The firm was established as Damsgaard Motorfabrikk by two brothers, Alf and Håkon Söyland in 1925. The firm started building engines ...
, produced a number of small marine diesel engines, mostly
single-cylinder or
twin-cylinder units, that used splash lubrication.
Modern use of splash lubrication
Splash lubrication is still used in modern engines and mechanisms,
[Lubrication systems https://learnmechanical.com/lubrication-system/] such as:
* the
Robinson R22 helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attribut ...
uses splash lubrication on some
bevel gear
Bevel gears are gears where the axes of the two shafts intersect and the tooth-bearing faces of the gears themselves are conically shaped. Bevel gears are most often mounted on shafts that are 90 degrees apart, but can be designed to work at ot ...
s.
* all
BMW motorcycle
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, cruisin ...
s with shaft drive use splash lubrication in the final drive hub.
* British
pre-unit and
unit construction : ''For the vehicle design where the vehicle's skin is used as a load-bearing element, see Monocoque.''
Unit construction is the design of larger motorcycles where the engine and gearbox components share a single casing. This sometimes includes ...
motorcycle
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, cruisin ...
s, (such as
Triumph,
BSA and
Norton) used splash lubrication in their gearboxes.
* Cars and lorries invariably still use splash lubrication in their
differentials.
See also
*
Oil pressure
References
External links
International Council for Machinery LubricationMachinery Lubrication magazine
Lubrication
Tribology
Lubricants
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