Clear definitions for the materials, bearing forms and lubrication principles used in hydrodynamic bearing work.
A bearing can be described by its running material, supported load, mechanical form and lubrication principle at the same time.
What the lined running surface is made from.
Whether the bearing supports radial or axial load.
How the load-carrying surface is constructed.
How lubricant pressure separates the moving surfaces.
Babbitt, with two final t's, is the established name for a family of soft bearing alloys associated with Isaac Babbitt's original patent. Babbit is a common search spelling. In industrial bearing use, Babbitt is broadly equivalent to whitemetal, but the precise tin- or lead-based grade still matters.
The stronger component supporting the bearing lining. It may be steel, bronze, copper chrome zirconium or another engineered material. The backing provides structure and can strongly affect heat transfer and distortion.
The material forming the running surface of a lined bearing. In Oiltech's core applications this is normally a bonded layer of whitemetal or Babbitt on a stronger backing. See the whitemetal lining thickness guide for design and repair considerations.
Temperature measured by a sensor embedded in or beneath the bearing lining. It differs from supply oil, drain oil and local surface temperature, and depends strongly on sensor position and depth. See the bearing temperature-limits guide.
The designed difference between bearing bore and shaft size. Radial clearance is the gap on one side with the shaft centred; diametral clearance is twice the radial value. State which one is being used.
The rotating surface that runs against the thrust bearing pads. Collar is common when the thrust surface is integral with or fitted to the shaft; runner is also used for the rotating mating component.
A controlled oil-supply arrangement that delivers fresh lubricant to the leading edge or inlet of individual pads, reducing hot-oil carryover, churning loss and temperature compared with some flooded arrangements.
The permitted axial movement of a shaft between its thrust-control surfaces. It is an assembly and machine-system value, not simply a pad or lining dimension.
A tilting-pad thrust bearing with a mechanical support system that helps distribute load between pads and accommodate limited misalignment. Non-equalising bearings rely more directly on accurate pad and collar geometry.
A bearing whose running geometry is machined into a stationary bore or face. Sleeve, cylindrical, lemon-bore, multi-lobe and taper-land designs are examples. The surface does not tilt independently like a tilting pad.
An arrangement in which the bearing cavity is substantially filled with lubricant. It is robust and widely used, but high-speed operation can create additional churning and viscous losses.
A bearing in which the stationary and rotating surfaces are separated during normal operation by a load-carrying film of fluid. Oil-film bearings are one subset; other designs can use water, air or process fluid.
Relative motion draws lubricant into a converging gap and generates pressure within the film. That internally generated pressure supports the load. Read the hydrodynamic lubrication guide.
Externally pressurised lubricant supports or lifts the shaft independently of normal running speed. Jacking-oil systems use this principle during start-up, shutdown or low-speed turning.
The cylindrical shaft surface that rotates within a journal bearing. The term describes the shaft surface, not the bearing itself.
A plain bearing supporting load acting radially across a rotating shaft. Journal bearings include fixed-profile sleeve bearings and tilting-pad journal bearings. See Oiltech's journal bearing range.
The leading edge is where the rotating surface first draws lubricant onto a pad or land. The trailing edge is where lubricant leaves the loaded film. They reverse when the direction of rotation reverses.
A regime in which part of the load is carried by the fluid film and part through local surface contact. It can occur during acceleration, coast-down, overload or inadequate film formation.
The thin layer of oil separating moving surfaces. An oil-film bearing is a fluid-film bearing specifically using oil; fluid film is the wider term.
An individual load-carrying segment in a tilting-pad journal or thrust bearing. Pad and shoe are often used interchangeably, although local product terminology may prefer one.
The support about which a bearing pad tilts to form its hydrodynamic wedge. Pivot geometry, alignment freedom and centre or offset position influence pressure, temperature and load distribution.
A bearing in which load is supported across sliding surfaces rather than rolling elements. It is the broad family containing bushes, sleeve bearings, journal bearings and many thrust bearings.
A geometric ratio used particularly in profiled and tilting-pad journal bearings to relate assembled clearance to machined pad clearance. It influences shaft position, stiffness and damping, and is not an externally applied machine load. Read the journal bearing preload guide.
A fixed-profile journal bearing with a continuous bore around the shaft, often cylindrical or specially profiled. It is a type of journal bearing, but not every journal bearing is a sleeve bearing.
Applied load divided by a stated reference area. For journal bearings this is often projected area, diameter times effective length. For thrust bearings it is normally based on active pad area. Always state the area convention.
A local linear description of how bearing reaction force changes with small shaft displacement and velocity about an operating point. Direct and cross-coupled terms are used in critical-speed, response and stability calculations. Read the bearing coefficient guide.
A bearing supporting load acting along the shaft axis. Designs include plain thrust faces, taper-land bearings and fixed or equalising tilting-pad assemblies. See Oiltech's thrust bearing range.
A journal or thrust bearing made from independently supported pads that tilt to establish a load-carrying wedge. Pad geometry, pivot type, offset and lubrication are selected for the duty.
Common names for the soft metallic lining used on many industrial plain bearings. Whitemetal is common UK industry usage; white metal is the spaced search form. In bearing applications both are broadly synonymous with Babbitt.
Directional smearing, displacement or melting of the bearing lining following loss of adequate film separation. It describes the damage appearance; oil starvation, overload, misalignment or overheating may be the initiating cause.
No matching term. Try a broader word or ask Oiltech's engineering team.
Broadly yes in bearing applications. They describe the family of soft bearing alloys used as a lining, but they do not identify the exact alloy grade. Material specification and composition remain important.
A sleeve bearing is one type of journal bearing. Journal bearing is the broader radial-load category and also includes tilting-pad and other fixed-profile designs.
Oil-film bearings are fluid-film bearings using oil. Fluid film is broader because water, air or process fluid can also separate the surfaces in suitable designs.
No. Hydrodynamic pressure is generated by motion through a converging film. Hydrostatic pressure is supplied externally and can support load without normal running speed.
The glossary is aligned with current plain-bearing terminology in ISO 4378-1:2024 for bearing design and materials and ISO 4378-3:2024 for lubrication. Definitions are written for practical industrial use rather than reproduced from the standards.
Continue with the hydrodynamic lubrication guide to see how motion, geometry and oil viscosity create a load-carrying film.