Document ID: chunk:federal_register_of_legislation:F2015C00542:reg:1:p16
Version: federal_register_of_legislation:F2015C00542
Segment Type: reg
Provision Reference: reg 1 (pt 16/43)
Character Range: 186932–189846

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4. Optical qualities
4.1. The provisions concerning regular light transmittance set out in Annex 3, paragraph 9.1., shall apply to uniformly-toughened glass panes or parts of glass panes located at places which are essential to the driver's vision.
4.2. The provisions of paragraph 9. of Annex 3 shall apply to uniformly-toughened glass panes used as windscreens of slow-moving vehicles which, by construction, cannot exceed 40 km/h. This shall not apply to flat windscreens which fall within an already approved group.

Annex 6
  Ordinary laminated-glass windscreens
1. Definition of type
 Ordinary laminated-glass windscreens shall be deemed to belong to different types if they differ in at least one of the fallowing principal or secondary characteristics.
1.1. The principal characteristics are as follows:
1.1.1. The trade names or marks.
1.1.2. The shape and dimensions,
 Ordinary laminated-glass windscreens shall be deemed to belong to one group for the purposes of tests of mechanical properties and of resistance to the environment.
1.1.3. The number of layers of glass,
1.1.4. The nominal thickness 'e' of the windscreen, a manufacturing tolerance of
0.2 . n mm ('n' being the number of layers of glass in the windscreen) above or below the nominal value being allowed,
1.1.5. The nominal thickness of the interlayer or interlayers,
1.1.6. The nature and type of the interlayer or interlayers (e.g. PVB or other plastics-material interlayer or interlayers).
1.2. The secondary characteristics are as follows:
1.2.1. The nature of the material (polished (plate) glass, float glass, sheet glass),
1.2.2. The colouring (total or partial) of the interlayer or interlayers (colourless or tinted),
1.2.3. The colouring of the glass (colourless or tinted),
1.2.4. The incorporation or otherwise of conductors,
1.2.5. The incorporation or otherwise of opaque obscuration.
2. General
2.1. In the case of ordinary laminated-glass windscreens, tests other than headform tests (paragraph 3.2. below) and tests of optical qualities shall be conducted on flat test pieces which are either cut from actual windscreens or are specially made for the purpose. In either case the test pieces shall be in all respects rigorously representative of the serially-produced windscreens for which approval is sought.
2.2. Before each test the test pieces shall be stored for not less than four hours at a temperature of 23 °C ± 2 °C. The tests shall take place as soon as possible after the test pieces have been taken out of the receptacle in which they were stored.
3. Headform test
3.1. Indices of difficulty of the secondary characteristics
 No secondary characteristic is involved.
3.2. Headform test on a complete windscreen
3.2.1. Number of test pieces
 Four test pieces from the smallest-developed-area series and four samples from the largest-developed-area series selected in accordance with the provisions of