Design & selection
Bearings
General bearing knowledge and the design tools that support it. For the specialist gas-bearing core — aerostatic, spiral-groove and narrow-groove — see Gas Bearings.
Calculators
Rolling bearing basic rating life (L10)Basic (L10) rating life of a rolling bearing, in millions of revolutions and in operating hours, from the catalogue dynamic load rating, equivalent bearing load and rotational speed.Equivalent dynamic bearing loadEquivalent dynamic bearing load P for a single-row deep-groove ball bearing under combined radial and axial load, from the SKF e/X/Y factor tables for Normal/C3/C4 radial clearance.Water-lubricated journal bearingPV-value, side-leakage flow, power loss and frictional temperature rise of a water-lubricated journal bearing operating at near-full eccentricity, assuming adiabatic conditions.Hydrostatic circular thrust pad with restrictor choiceLoad capacity, stiffness, flow rate and pump power for a circular hydrostatic thrust pad, with a choice of capillary, orifice or fixed-flow restrictor — after the hydrostatic bearings of the Prins Willem-Alexander locks in Amsterdam.Hydrostatic bearing — wedge-film thrust padDimensionless load, stiffness and load-sensitivity for a wedge-film hydrostatic thrust pad, from the film-thickness ratio h1/h0.Hydrostatic bearing — shallow-recess thrust padDimensionless load, stiffness and load-sensitivity for a shallow-recess hydrostatic thrust pad, from the recess-area and film-thickness ratios.Hydrostatic 4-chamber thrust bearingLoad, stiffness, flow and power for a hydrostatic 4-chamber thrust bearing, with a choice of capillary, orifice, or fixed-flow restrictor.Hydrostatic journal bearing, externally pressurizedLoad, stiffness, flow and power for an externally pressurized hydrostatic journal bearing — separated or connected recess elements, with a choice of restrictor.Partially grooved hydrostatic journal bearingLoad and flow for a partially grooved, externally pressurized hydrostatic journal bearing with k grooves, by numerical summation around the circumference.Hydrostatic shallow-pocket liquid thrust bearing — fixed reference geometryReference-geometry calculator (Ø40mm bearing, 5µm film — fixed, matching the original) for a hydrostatic shallow-pocket liquid thrust bearing fed through a small central inlet hole. Vary pocket/inlet diameter, pressures and viscosity.Hydrostatic thrust bearing, central pocket, capillary restrictor — fixed reference geometryReference-geometry calculator (60mm bearing radius — fixed, matching the original) for a circular hydrostatic thrust bearing with a central pocket fed through a capillary restrictor. Vary pocket radius, film thickness, pressure and fluid properties.Orifice-compensated hydrostatic thrust bearing, central pocket — fixed reference geometryReference-geometry calculator (60mm bearing radius — fixed, matching the original) for a circular hydrostatic thrust bearing with a central pocket fed through a sharp-edged orifice. Vary pocket radius, film thickness, pressure and fluid properties.Orifice-compensated hydrostatic thrust bearing, central pocket (lock-gate scale) — fixed reference geometryReference-geometry calculator (650mm bearing diameter, 0.1mm film thickness, 0.7 pressure factor — all fixed, matching the original) for the alternative single-pocket design to the 4-pocket hydrostatic lock-gate bearings of the Prins Willem Alexander Lock in Amsterdam.Hydrostatic journal bearing, multi-recess — fixed reference geometryReference-geometry calculator (60mm shaft diameter, L/D=1, 50 bar supply pressure — all fixed, matching the original) for an externally pressurized journal bearing with 4 or 5 pockets and a choice of capillary, orifice or fixed-flow restrictor.Hydrostatic collar bearing, slot feed through orifices — fixed reference geometryReference-geometry calculator (40mm outer diameter — fixed, matching the original) for a hydrostatic thrust collar bearing fed via a circumferential groove supplied by discrete orifices. Vary groove/inner diameter, film thickness, pressures and fluid properties.Hydrostatic thrust bearing, single center pocket — fixed reference geometryReference-geometry calculator (650mm bearing diameter, 0.1mm film, β=0.7 — fixed, matching the original) for a single-pocket, multi-orifice hydrostatic thrust bearing. Vary pocket diameter, supply pressure and fluid properties.Pivot bearing — contact pressure and friction torqueContact pressure (Hertz, with interpolation to a plastic/Brinell regime at high loads) and friction torque/power for a pivot bearing ("boltaats").Tilting-pad (Michell) bearing — rectangular padLoad capacity, friction coefficient and film-thickness/eccentricity numbers for a rectangular Michell tilting-pad bearing, sized as a compromise between minimum friction and maximum film thickness.Hydrodynamic journal bearingSommerfeld number, attitude angle, friction, load capacity, stiffness, side leakage and frictional heating for a finite-length hydrodynamic journal bearing. Unlocked from the legacy demo gate; general in shaft diameter, clearance and film thickness.Hydrodynamic bearing under shock (impulsive) loadDimensionless and dimensional impulse capacity of a finite-length hydrodynamic journal bearing (π-film boundary condition) subjected to a shock/impact load.Design of a hydrodynamically lubricated plain bearingSommerfeld number, attitude angle, friction and flow numbers, plus load capacity, friction coefficient and lubricant flow for a hydrodynamically lubricated plain (journal) bearing, from length ratio, eccentricity, clearance ratio, radius, speed and viscosity.Journal bearing — oil flow / pressure dropPressure drop across a journal bearing film needed to produce a prescribed axial (cooling) flow rate, from shaft diameter, bearing length, radial clearance, eccentricity and viscosity.Static load capacity of polymer (thermoplastic) bearingsElastic indentation, contact geometry, load capacity and stiffness of a thermoplastic sliding bearing bush from shaft diameter, bearing length, wall thickness, modulus of elasticity, radial clearance and allowable contact pressure.Load capacity and stiffness of guide ringsContact geometry, load capacity and stiffness of a resilient thermoplastic guide (wear) ring supporting a piston/rod, from piston diameter, ring width/thickness, elastic indentation, radial clearance and modulus of elasticity. Unlocked from the legacy demo gate; general in shaft diameter and indentation.Static load rating of a deep-groove ball bearing (Hertz)Elliptical (Hertzian) contact pressure for a prescribed bearing load, and the ISO 76:1987 basic static load rating C0 for a prescribed maximum contact pressure, from ball and raceway elastic properties and curvatures.Friction in a ball-cage linear guideHertzian contact stiffness and pressure of a single ball in a ball-cage linear guide (loaded at 45° to the guide axis), plus the resulting sliding friction force and coefficient.