ISO 6526:2017

Overview

ISO 6526:2017 specifies the features and tolerances for pressed bimetallic half thrust washers (plain bearings) with an outside diameter up to 160 mm. All linear dimensions and tolerances are expressed in millimetres. The standard defines geometric and manufacturing tolerances (diameters, heights, total thickness, lugs, grooves, fillets, chamfers, flatness), but does not prescribe main nominal dimensions or materials and makes no general specification for surface roughness.

Key topics and requirements

• Scope limit: applies to pressed bimetallic half thrust washers with outside diameter ≤ 160 mm.
• Units: all linear dimensions in millimetres.
• General tolerances: unspecified linear dimensions ±0.25 mm; angular ±5°.
• Diameter and height tolerances: specific tolerances for outside (D) and inside (d) diameters and for heights (H, F) are tabulated. Example: outside diameter tolerance is −0.25 mm for D ≤ 120 mm.
• Thickness (eT): preferred total thickness values (e.g., 1.75, 2.0, 2.5, 3.0 mm) with corresponding negative tolerances and recommendations for oversizes.
• Geometric relations: the difference D − d shall be greater than 7 · eT (outside minus inside diameter greater than seven times total thickness).
• Locating lug: dimensions for lug width (A), lug length (E) and notch recess (JS13 per ISO 286‑2) are specified; lug may be offset to prevent incorrect assembly.
• Grooves: groove width, back-wall thickness, and radial position tolerances are defined (including positional tolerances increasing with diameter).
• Fillets and chamfers: maximum radii and chamfer widths for lug, joint faces and sliding surfaces; joint-face relief depth limits (≤ 30 % of total thickness) and relief angle β ≤ 30°.
• Flatness: half washers must slide between parallel plates set to eT + p, with p specified by diameter range (e.g., p = 0.10 mm for D ≤ 80 mm).
• Surface roughness: not specified due to material variability.

Applications

ISO 6526:2017 is used where pressed bimetallic half thrust washers serve as thrust plain bearing elements in rotating and sliding assemblies. Typical applications include:

• Engine and gearbox thrust guidance
• Transmission assemblies and rotating machinery
• Repair, remanufacture and replacement of standard thrust washer components

Who uses this standard

• Bearing and component manufacturers (production, tool design)
• Mechanical designers and OEMs specifying thrust washer components
• Quality and inspection engineers (acceptance criteria)
• Procurement and maintenance teams sourcing interchangeably specified washers

Related standards

• ISO 286‑2 - tolerances on linear sizes (referenced for notch recess JS13)
• ISO/TC 123 - technical committee for plain bearing standards

Keywords: ISO 6526:2017, plain bearings, pressed bimetallic half thrust washers, tolerances, diameters, lug, groove, flatness, thrust washer standard.