Ring oiler

A ring oiler or oil ring is a form of oil-lubrication system for bearings.

Ring oilers were used for medium-speed applications with moderate loads, during the first half of the 20th century. These represented the later years of the stationary steam engine, and the beginnings of the high-speed steam engine, the internal combustion oil engine[1] and electrical generating equipment.[2] Before this time plain bearings were lubricated by drip-feed oil cups or manually by an engine tender with an oil can. As speeds or bearing loads later increased, forced pressure lubrication became more prevalent and the ring oiler fell from use.

A ring oiler is a simple device, consisting of a large metal ring placed around a horizontal shaft, adjacent to a bearing. An oil sump is underneath this shaft and the ring is large enough to dip into the oil. As the shaft rotates, the ring is carried round with it. The rotating ring in turn picks up some oil and deposits it onto the shaft, from where it flows sideways and lubricates the bearings. The oil ring is effectively a simple lubrication pump, with only one moving part and no complex or high-precision components. The device is crude, but automatic, effective and reliable. Unlike a drip oiler, there is also no need to close off the oiler or remove oil wicks when the machine is stopped.

Ring oilers were used for speeds up to around 1,000 rpm.[1] Above this, the oil tended to be thrown centrifugally from the ring, rather than carried by it (although it is still currently applied on steam turbines with speeds around 3200 rpm). The bearing must also remain horizontal and stable, so although suitable for crankshaft main bearings, they could not be used on connecting rod big end bearings. They were not used on vehicles for similar reasons, although the engines concerned at this time were anyway too large and heavy for practical mobile use. Automatic ring oilers were particularly useful for large engines with multiple horizontally opposed cylinders, where it was otherwise difficult to access the central main bearings.[1] Ring oilers were most suited where bearing side-loads were relatively light, but the bearing capacity required more lubrication than could be supplied by a drip feed oiler. For this reason they were widely used on larger electric motors and generators.[2][3]

Bearing with ring oiler, coloured (Electrical Machinery, 1917)
Section through a bearing, showing the oil sump beneath (green) and the ring oiler (orange) in place around the shaft
Bearing with ring oiler, longitudinal section (Electrical Machinery, 1917)
Section though a long Babbitt metal sleeve bearing, with two ring oilers fitted through grooves in the upper part of the bearing.


  1. ^ a b c Williams, D.S.D.; Millar Smith, J. (1939). The Oil Engine (journal) (ed.). The Oil Engine Manual. London: Temple Press. pp. 65–67.
  2. ^ a b Croft, Terrell (1917). Electrical Machinery. McGraw-Hill. p. 144.
  3. ^ "Lubrication". p. 6-3.
Bearing (mechanical)

A bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Most bearings facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts.

Rotary bearings hold rotating components such as shafts or axles within mechanical systems, and transfer axial and radial loads from the source of the load to the structure supporting it. The simplest form of bearing, the plain bearing, consists of a shaft rotating in a hole. Lubrication is often used to reduce friction. In the ball bearing and roller bearing, to prevent sliding friction, rolling elements such as rollers or balls with a circular cross-section are located between the races or journals of the bearing assembly. A wide variety of bearing designs exists to allow the demands of the application to be correctly met for maximum efficiency, reliability, durability and performance.

The term "bearing" is derived from the verb "to bear"; a bearing being a machine element that allows one part to bear (i.e., to support) another. The simplest bearings are bearing surfaces, cut or formed into a part, with varying degrees of control over the form, size, roughness and location of the surface. Other bearings are separate devices installed into a machine or machine part. The most sophisticated bearings for the most demanding applications are very precise devices; their manufacture requires some of the highest standards of current technology.

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. This lubricates the bearings, allows the use of higher-capacity fluid bearings and also assists in cooling the engine.

As well as its primary purpose for lubrication, pressurized oil is increasingly used as a hydraulic fluid to power small actuators. One of the first notable uses in this way was for hydraulic tappets in camshaft and valve actuation. Increasingly common recent uses may include the tensioner for a timing belt or variators for variable valve timing systems.

Oiler (occupation)

An oiler (also known as a "greaser") is a worker whose main job is to oil machinery. In previous eras there were oiler positions in various industries, including maritime work (naval and commercial), railroading, steelmaking, and mining. Today most such positions have been eliminated through technological change; lubrication tends to require less human intervention, so that workers seldom have oiling as a principal duty. In the days of ubiquitous plain bearings, oiling was often a job description in and of itself.

Today, shipping is the economic segment that most thoroughly retains the notion of the oiler as a separate position. On a merchant ship, an oiler is an unlicensed rate of the engineering department. The position is of the junior rate in the engine room of a ship. The oiler is senior only to a wiper. Once a sufficient amount of sea time is acquired, the Oiler can apply to take a series of courses/examinations to become certified as an engineer.

As a member of the engineering department, the oiler operates and maintains the propulsion and other systems on board the vessel. Oilers also deal with the "hotel" facilities on board, notably the sewage, lighting, air conditioning, and water systems. They assist bulk fuel transfers and require training in firefighting and first aid. Moreover, oilers help facilitate operation of the ship's boats and other nautical tasks – especially with cargo loading/discharging gear and safety systems. However, the specific cargo discharge function remains the responsibility of deck officers and deck workers.

Plain bearing

A plain bearing, or more commonly sliding bearing and slide bearing (in railroading sometimes called a solid bearing or friction bearing), is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Therefore, the journal (i.e., the part of the shaft in contact with the bearing) slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion; e.g., a drawer and the slides it rests on or the ways on the bed of a lathe.

Plain bearings, in general, are the least expensive type of bearing. They are also compact and lightweight, and they have a high load-carrying capacity.

Total-loss oiling system

A total-loss oiling system is an engine lubrication system whereby oil is introduced into the engine, and then either burned or ejected overboard. Now rare in four-stroke engines, total loss oiling is still used in many two-stroke engines.

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