Principal Investigators: Julie Mansfield, MS, The Ohio State University; John H. Bolte IV, PhD, The Ohio State University
WHAT WAS THE PURPOSE OF THIS PROJECT?
This study seeks to establish a method for CRS test engineers to tighten the harness on the CRS consistently. If you are testing 10 CRS in a day, you need to ensure they are all set up identically so that variability in harness tension does not influence the crash test results.
HAS THIS BEEN A SIGNIFICANT CONCERN?
There is some suspicion in the industry that it might be a problem. Unfortunately, variations in crash test setup can come from several sources, such as different tension in the harnesses or seat belts or different angles at which the ATD or the CRS is positioned. Our industry representatives in CChIPS suggested studying harness tightening methods across different test facilities to improve the procedure.
HOW WAS THE STUDY CONDUCTED AND WHAT WERE THE FINDINGS?
We recruited seven different associates across four companies within CChIPS. At each of their facilities, they tightened the harness of a CRS using five different methods, with each person conducting a total of 100 different trials.
We found substantial variability in the repeatability of each harness tightening method. However, we discovered two promising tightening methods. One was a 3-prong tension gauge that is clipped onto the harness webbing and measures the tension in that portion of harness. It is a fairly reliable tool that produced repeatable results across different users. The users also liked having a tool that provided an objective reading.
A second somewhat effective method was the “two finger test” in which the operators simply slide two fingers underneath the harness to feel its tightness. The reproducibility for this method was poor, which means that different people have different ideas about how tight is tight enough. However, once users established a feel for their target tension, they were able to produce similar tension trial after trial.
We are hoping these results can help create more harmonization across different facilities and perhaps even establish a better standard for harness tightening procedures.
Gretchen Baker, The Ohio State University; Stephen Rudolph, The Ohio State University
Keith Nagelski, Britax Child Safety, Inc.; Eric Dahle, Goodbaby International; Yibing Shi, FCA US LLC; Lan Xu, FCA US LLC; Kendal Fowler, Graco Children’s Products Inc.; Mark LaPlante, Graco Children’s Products Inc.; Jerry Wang, Humanetics Innovative Solutions Inc.; Jason Stammen, National Highway Traffic Safety Administration; Hiromasa Tanji, TK Holdings Inc.; Julie Kleinert, Emeritus Chair; Uwe Meissner, Technical Advisor