Overview
ISO 11687-3:2020 - Plain bearings - Pedestal plain bearings - Part 3: Centre flange bearings specifies design characteristics for centre flange bearings and associated shaft design for the size range 9 to 28. Intended mainly for the electrical and turbo engineering industries, the standard defines dimensional limits, material choices, surface finish, tolerances and designation conventions used when specifying or manufacturing centre flange pedestal plain bearings.
Key topics and requirements
- Scope and sizes: Applies to centre flange bearings in size range 9–28 and provides corresponding shaft dimensions (see Tables 1 & 2 in the standard).
- Types and coding: Bearing features are designated by letter symbols for housing (e.g., M = housing with cooling fins), heat dissipation (N, W, U, T, Z), bore shape and lubrication (C, L, Y, V), thrust bearing type (Q, B, K, A) and seals.
- Dimensions and interchangeability: The standard prescribes critical dimensions for housings and half‑bearings; conformance is required to specified dimensions though detailed designs can vary.
- Shaft design and fits: Shaft limits, tolerances, form and surface roughness are specified (references to ISO 12129‑1 and ISO 12129‑2).
- Materials: Recommendations include housing material grade 300 (ISO 185); half‑bearing back options (S235 B per ISO 630‑2, C10R/C15R per ISO 683‑3 or GE/GS 200 per ISO 14737); bearing metal as tin‑casting alloy (ISO 4381); and oil ring and seal materials (ASTM B124/B124M and others by agreement).
- Surface finish and tolerances: Surface roughness per ISO 1302 - sliding surfaces Ra = 0.8 µm, mounted surfaces Ra = 3.2 µm. General machining tolerances per ISO 2768‑1 and ISO 2768‑2 (mH); unmachined surfaces per ISO 8062‑3 (DCTG 9 for grade 300).
- Housing and design details: Requirements for lifting/conveyance means, oil‑resistant inner paint, corrosion protection, pressure compensation between oil spaces, and connection arrangements (connections to be provided on both sides or by agreement).
- Designation example: Centre flange bearing ISO 11687‑3 - 14 - 125 - MZLK (size 14, shaft 125 mm, M housing, Z lubrication, L bore, K thrust).
Applications and users
- Who uses it: Mechanical design engineers, bearing manufacturers, OEMs in electrical generators/turbomachinery, maintenance engineers, procurement/specification writers.
- Where used: Support and guiding bearings in generators, turbines and other rotating equipment where pedestal centre flange bearings are required, ensuring interchangeability, correct lubrication, material compatibility and serviceability.
Related standards
Normative references include ISO 185, ISO 630‑2, ISO 683‑3, ISO 1302, ISO 2768‑1/2, ISO 8062‑3, ISO 12129‑1/2, ISO 4381, ISO 14737 and ASTM B124/B124M - useful cross‑references when specifying materials, tolerances and surface requirements.
Keywords: ISO 11687-3:2020, centre flange bearings, pedestal plain bearings, shaft design, surface roughness, bearing materials, bearing dimensions, electrical engineering, turbo engineering.