Overview
ISO 5679:1979 - Equipment for working the soil - Disks - Classification, main fixing dimensions and specifications - defines interchangeability dimensions and basic specifications for agricultural disks. The standard classifies disks into three types (A, B and C), gives nominal fixing dimensions for concave disks (various variants of Type B and Type C), and specifies tolerances, flatness and edge bevelling rules to ensure compatibility across ploughs, harrows and disk-tillers.
Key topics and technical requirements
- Classification
- Type A: Flat disks (reference: ISO/TR 4122).
- Type B: Concave disks with three variants:
- Variant 1 - square centre hole (Figure 1)
- Variant 2 - round centre hole (Figure 2)
- Variant 3 - several fixing holes, with or without centre hole (Figure 3)
- Type C: Concave disks with a flat area around the centre hole (Figure 4).
- Nominal fixing dimensions
- Main interchangeability dimensions for concave disks are tabulated (Table 1 for centre-hole variants; Table 2 for multiple-fixing-hole variant).
- Edge bevelling
- Flat disks: bevelled on both sides.
- Concave disks: bevelled on either concave or convex side.
- Maximum cutting-edge thickness: 0.8 mm.
- Eccentricity and wobble
- Type A (flat): eccentricity and wobble ≤ 0.5% of outside diameter.
- Types B and C: allowable eccentricity/wobble given in Table 3 (values increase with nominal diameter).
- Flatness and distortion
- Flat disks: maximum distortion when laid flat - 1.6 mm for diameters ≤ 510 mm; 2.5 mm for > 510 mm.
- Concave disks (Type B): distortion ≤ 5 mm when laid on a flat surface.
- Local edge distortions limited to 0.3% of outside diameter (measured radially).
Applications and who uses it
- Ensures interchangeability of agricultural disks across manufacturers and implements.
- Primary users:
- Disk and agricultural implement manufacturers and component designers
- Quality control and inspection teams (tolerance checks, flatness, eccentricity)
- Procurement and maintenance teams specifying replacement disks for ploughs, harrows and disk-tillers
- Standards bodies and testing laboratories
- Practical benefits:
- Reduced SKU proliferation through standardized nominal sizes and fixing dimensions
- Easier sourcing of replacement disks and improved compatibility between implements
Related standards
- ISO/TR 4122 - referenced for dimensions of flat (Type A) disks.
- Other ISO agricultural machinery standards may be consulted for implement interfaces and safety requirements.
Keywords: ISO 5679:1979, agricultural disks, concave disks, flat disks, interchangeability, fixing dimensions, eccentricity, wobble, ploughs, harrows, disk-tillers.