EN ISO 28927-2:2009/A1:2017 PDF

Overview

EN ISO 28927-2:2009/A1:2017 is a CEN-endorsed amendment to ISO 28927-2 (Part 2 of the ISO 28927 series) that updates test methods for evaluating vibration emission from hand-held portable power tools - specifically wrenches, nutrunners and screwdrivers. Amendment A1 replaces Annex C (brake device specification) and adds Annex D (example brake-block drawings and parts tables). The changes clarify the brake-device design, assembly and test-rig requirements used when measuring tool vibration (hand–arm vibration).

Key topics and technical requirements

• Brake device specification (Annex C)

  • Socket sizes and weights are defined (see Figures C.1–C.5) to ensure repeatable loading.
  • The difference between static and dynamic friction coefficients of the brake must be ≤ 20%.
  • Brake force variation during a test run must not exceed ±20%; use of conical disc springs is recommended to meet this requirement (other designs may be used if verified by measurement).
  • The mounted test rig must not exhibit resonances in the hand–arm vibration frequency range; recommended practice is bolting the base frame to a concrete block ≥ 400 kg.

• Brake-block design and parts (Annex D)

  • Includes example drawings, bill-of-materials and sizing for large and small brake devices, brake blocks, cover plates, sockets, springs, bolts and washers.
  • Brake blocks may be phenolic laminate or aluminium with a friction lining; lining material must be tested so static/dynamic friction difference is