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Document Title TRL EC child safety project–summary of chest behaviour results
Reference Number CRS-54-09
Date
28 Oct 2015
Summary Summary of investigations into belt slippage (clavicle and neck) and chest deflection to define areas for improvement of the test procedures under UN R129.
Source(s) TRL
Rulemaking Area(s) UN R129 Enhanced Child Restraints
Meeting(s)
Downloads
UNECE server .pdf format
Excerpts from session reports related to this document
CRS | Session 54 | 27 Oct 2015

6.3.2. CRS-54-09e on chest behaviour results. The Q-series dummies are able to measure chest deflection (P-series dummies are not) but the shoulder belt tends to move towards the neck. The maximum deflection is due to chin to chest contact. Chest deflection limits are proposed but still not validated. We can see some potential solutions to solve previous problems by creating a test environment that prevents belt slippage from occurring, propose an assessment procedure for the static belt lie & useful injury threshold limits. For this study, deflections were measured on the clavicle for the Q3 & Q6 dummy.

However, during testing a bottoming-out was observed; there was a hard contact between clavicle and neck bracket. Two input conditions were tested (R129 & extreme D ring position) without CRs, with booster seat & with booster cushion.

In conclusion and for summary:

  • the shoulder belt tends to slip toward the neck with Q3 & Q6 dummy,
  • Confirmed clavicle to neck bracket contact affects chest deflection measurements,
  • CRS seem safe using R129 setup with Q3,
  • For Q6 an extreme upper anchorage position can influence belt path and interaction,
  • The belt stays on Q10 shoulder.

Recommendations for TRL are:
  • To test with modifications to upper anchorage position,
  • Can we “fix” the Q3 dummy shoulder & clavicle?
  • Need a static belt path assessment, if nothing else exercises belt guides