Overview - ISO/TR 20571:2018 (Dynaload)
ISO/TR 20571:2018 is a technical report that specifies the design, construction, use and maintenance of the Dynaload - a dynamic loading device used with hand‑held power tools (percussive and rotary‑percussive). The Dynaload is a metallic cylinder filled with steel balls that absorbs blow energy from tools and is intended for use during vibration testing, noise measurement, and other test standards that require a reproducible working load.
Key topics and technical requirements
- Basic construction: The Dynaload is a cylinder containing steel balls and a tool interface (tool piece and tool foot). It may be mounted on a surface or buried below ground for tests such as concrete breaker assessments.
- Device name: Commonly referred to as DYNALOAD in test specifications.
- Preferred sizes: Two standard internal cylinder diameters are cited - 40 mm and 60 mm - chosen according to tool power and absorbed power capability.
- Tool interface types:
- Type 1 - one‑piece solid formed tool piece and tool foot (unitary assembly). Optional recoil spring described.
- Type 2 - two‑piece tapered tool piece with a mating tool foot (taper fit).
- Energy behaviour: The device absorbs most shock; approximately 15%–20% of shock energy is reflected back to the tool, simulating normal working conditions.
- Cooling: Low‑pressure air through the steel balls is the preferred cooling method; alternative suction cooling is possible. Grease or oil is not permitted as coolant.
- Operational guidance:
- New ball charge should be run for 15 minutes to allow settling (running‑in).
- Replace the full charge when surface fragmentation appears; do not mix old and new balls.
- Specified tool piece lengths must not be exceeded to avoid flexing and measurement errors.
- Maintenance: Simple construction but requires inspection for rust and ball wear; remove balls for long‑term storage or protect the cylinder.
Applications and users
- Use cases: vibration testing, noise measurement, tool performance testing, and any test standard that requires a reproducible dynamic load for percussive/rotary‑percussive hand tools.
- Typical users: test laboratories, standards committees, tool manufacturers, quality and compliance engineers, and safety professionals who perform standardized measurements of hand‑held power tools.
Related standards and references
- ISO/TR 20571 supplements test standards - notably it has been used alongside ISO 28927‑10 (vibration test code for percussive tools).
- Prepared by ISO/TC 118 (Compressors and pneumatic tools, Subcommittee SC 3).
Keywords: Dynaload, ISO/TR 20571, dynamic loading device, percussive hand‑held power tools, vibration testing, noise measurement, test rig, guide bush, steel balls, cooling, maintenance.