Sorry to be off topic of the Nautilus...
Mamabear:
Here is the email to Jody from Russ @SKJP about the Radians top slots:
Jody,
So here goes:
Radian's unique design and incredible strength permits a child's shoulders
to go above the top harness slots as long as the child's ears are below
thetop of Radian's seat back. While there will be some very tall 65 lb
occupants for whom this will make a difference, more practically it is
focused towards the Radian80 to allow the highest percentage of larger
andolder occupants to still be able to take advantage of Radian80's
harnessedcapacity and yet continue to maintain an overall height that allows the
flexibility of rear-facing.
Radian65 is the strongest car seat in its class and (to our knowledge)
Radian80 is the strongest car seat in the world.
So, how can Radian allow a child's shoulders to go above the top
harnessslot?
Simply put, both Radian65 and Radian80 were crash tested with large size
dummies whose shoulders were above the top harness positions and the
performance results were excellent. Currently there are NO established
governmental requirements for child seat certification when crash testing
with a test dummy above 50 lbs other than structural integrity (ie. no
breakage in the CRS). At Sunshine Kids, we have developed our own
internal requirements that go far above what is required by law. Even for the
80 lb child occupant, we have adopted the FMVSS213 excursion requirements for
the under-50 lb occupant of 720 mm with tether and 813 mm without tether.
As well, compliance to those same biomechanical requirements of FMVSS213
required for the under-50 lb occupant, we have decided to adopt for the
heavier occupants: below 60 G to the chest, under 1000 HIC for the head
injury criterion. As well, we have internal requirements for neck
loading - hence the use of Safe Stop for the lighter occupant.
The test dummies used for crash testing (whose shoulders are above the
top harness slots) were fully instrumented to record loads in all 3 vectors
of movement: X, Y and Z (i.e. fore-aft, horizontal and vertical). The
numerical values recorded during crash testing show that the biomechanical loads
experienced by the dummy in each of these three vectors. Results of
these crash test showed that all the biomechanical values were all well below
those values established by NHTSA in FMVSS213.
What this means is that even with the child's shoulders above the top
slots, Radian's vertical chest loading (Z- vector) was sufficiently low enough
(i.e. well within NHTSA's values) to demonstrate that there is no
excessive spinal loading.
The current trend to harness heavier occupants in child restraints
requires the restraints to be built in a manner that truly adjusts performance
for each size occupant as the physical characteristics of a 3 yr old are
very different that that of a 6, 7 or 8 year old. Radian's design embraces
that approach exemplified by Safe Stop energy management for the small
forward facing occupant, unmatched strength for the larger occupant and
incredible stability for the rear facing occupant up to 33 lbs.
Sunshine Kids' policy is to always encourage the use of top tether, as
long as its installation and intended use conforms to the instructions of
the vehicle and for the child with whom it will be used. There are some
professionals who take a well-thought, but different, position on this
issue. While we have great respect for their experience and knowledge,
as a car seat maker we must maintain a certain position on this matter that
does not compromise the instructions of the vehicle. The use of top tether
with the higher weight occupant (50 lb to 80 lb) in a harnessed child seat,
is not allowed by most if not all vehicle manufacturers. The fact that
the Radian can safely and conveniently utilize just the lap belt in these
heavy occupant applications gives the consumer the ability to safely secure
their child and follow all manufactures instructions (Child Restraint and Car
Manufacturers).
I understand and appreciate the concerns about shoulder harness heights
as it relates to safety and performance. I hope all this information helps
explain both our design and performance criteria.
Best regards,
Russ
------------------------------------
Sunshine Kids
Russ Berger
russ@skjp.com
147 Tower Avenue
Needham, MA 02494
USA
tel: 781-453-0309
fax: 305-574-0309
mobile: 617-817-3201
www.skjp.com