Overview
ISO 7918:1995 is an international standard focused on forestry machinery, specifically regulating the cutting attachment guard dimensions for portable brush-cutters and grass-trimmers powered by internal combustion engines. This standard aims to ensure the safety of operators working primarily in forestry environments by specifying the minimum size requirements for guards protecting users from accidental contact with cutting attachments. Not applicable to lawn-trimmers, ISO 7918:1995 addresses hand-held machines used for tougher, outdoor vegetation management tasks.
Developed by ISO Technical Committee ISO/TC 23/SC 17, this second edition replaces the 1985 version by extending coverage to various blade types beyond circular saws and broadening the scope of guards for multiple machine types.
Key Topics
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Cutting Attachment Guard Dimensions
Specifies minimum guard dimensions to provide adequate protection behind the cutting mechanism. These dimensions vary among:
- Brush-saws
- Brush-cutters (excluding brush-saws)
- Grass-trimmers
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Safety Design Criteria
The guard must cover a defined sector at the back of the cutting attachment and feature a rounded lower rear edge to prevent snagging on stumps or obstacles in forestry conditions.
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Clearance Specifications for Saw-Blades
Axial and radial clearances between saw-blades and guards are tightly regulated (maximum 3-4 mm axial clearance where the blade enters the guard, expanding to a minimum of 10 mm at discharge points) to prevent operator injury while maintaining effective cutting.
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Test Methods for Guard Strength
While ISO 7918:1995 focuses on dimensional requirements, it refers to ISO 8380 for mechanical safety and strength testing of the cutting attachment guards.
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Exclusions
Lawn-trimmers, as defined by ISO 10518, are explicitly excluded to focus the standard on forestry-specific applications.
Applications
ISO 7918:1995 is essential for manufacturers, forestry equipment designers, safety inspectors, and regulatory bodies involved in:
- Developing and certifying portable hand-held brush-cutters and grass-trimmers intended for forestry use.
- Ensuring operator safety by minimizing risks associated with contact or debris ejection from cutting attachments.
- Designing machine guards that comply with international minimum safety dimensions and reduce hazards related to forest environment operation.
- Facilitating compliance with international safety norms, enhancing machinery market acceptance, and meeting safety regulatory requirements in forestry machinery.
Related Standards
For comprehensive safety and performance in portable forestry cutting equipment, ISO 7918:1995 references and complements these standards:
- ISO 8380:1993 – Specifies mechanical safety requirements and test methods for cutting attachment guards’ strength.
- ISO 7113:1991 – Defines specifications for saw blades used in portable brush-saws.
- ISO 11806 (to be published) – Focuses on safety requirements and testing for manually portable forestry machines.
- ISO 10518:1991 – Defines powered walk-behind and hand-held lawn trimmers, helping distinguish the scope of ISO 7918 by excluding lawn-trimmer applications.
Keywords: ISO 7918, forestry machinery safety, brush-cutter guards, grass-trimmer dimensions, cutting attachment guard standard, portable forestry equipment, operator protection, mechanical hazards, brush-saw safety, machine guard dimensions.
Open preview (PDF)Forestry machinery — Portable brush-cutters and grass-trimmers — Cutting attachment guard dimensions
