Car Seat Safety: Correct Harness Positioning

This article is meant to help you understand why using the correct harness position is a key part of safe car seat use in daily life.

The Correct Harness Position for Rear-Facing Car Seats

Please note: The best thing you can do to make sure you are using your Orbit Baby car seat safely is to follow all product instructions, and regularly refer back to your car seat's manual.  In this article, we cover harness positioning for rear-facing car seats, including both our Infant Car Seat, and our Toddler Car Seat when used rear-facing.

Shoulder Harnesses: Overview

For all rear-facing car seats – not just Orbit Baby's – the correct positioning of the shoulder harness is at or below your child’s shoulders (see illustration at right). 

While this might seem like a simple rule, correctly setting the harness shoulder height is critical to your child being fully secured in the event of a sudden stop or impact.

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"DO NOT use shoulder strap slots that are above your child's shoulders. With the rear-facing Infant Car Seat, shoulder straps positioned in slots above the shoulders will not hold your child securely in a sudden stop or crash." - Orbit Baby Infant Car Seat Manual, page 53.

 

Orbit Baby's product instructions

The illustration below shows incorrect usage of a rear-facing car seat harness.  A version of this illustration appears in our manuals, along with the accompanying text:

Shoulder Harness: Concepts explained

Rear-Facing: Explaining the "At or Below" shoulder harness positioning

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Incorrect Installation

A harness slot above the child's shoulders can allow the child to move upwards.  As you can see in this illustration, a harness belt that is too high potentially allows for the child’s torso to travel twice the distance compared to the proper positioning below the shoulders. 

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Correct Installation

The harness straps are anchored snugly below a rear-facing child’s shoulders, and better restrain the child from sliding upwards. 

The widely known standard that a rear-facing child should have harness straps at or below their shoulders has to do with the way a child's body would move in a collision.  Simply put, many new parents don’t realize that putting shoulder harnesses too high for rear-facing car seats has a similar effect as not fully tightening the safety harness itself.  Most car collisions happen when the car is moving forward (including the 72% that are purely frontal or frontal-offset collisions (Ref1)), causing a rear-facing child’s back to be pressed against the seatback of the car seat.  This means that a main goal of a rear-facing car seat harness is to keep the child's body from sliding upwards against the car seat's seatback.

Any additional acceleration of the child upward influences the performance of any rear-facing car seat.  Also, every tiny increment of increased distance the child moves exponentially amplifies the forces on the child's body.  The more a child’s body accelerates, the more the child’s head and chest are subjected to increased g-forces both at the beginning of the collision and during the deceleration after the collision.

Shoulder slot positions relative to child size

Given all of the information above, some parents have asked us why we do not recommend certain harness positions for specific child weights or heights.  The reason is that the shoulder harness position depends only on your child’s seated "torso height," and there have been no studies we know of that correlate a child's torso length to the child’s height or weight.   As you can imagine, a big child could have a relatively short torso (in which case they might not use the top shoulder slots), or an average child could have a tall torso (in which case they might well need to use the top slot).

Confirming Shoulder Harness Positions: Test Lab Results

Proper harness positioning for rear-facing car seats

We have validated our instructions to position the shoulder harness at or below your child’s shoulders.  Two different independent labs have performed fitment tests on our Infant Car Seat to confirm this.

Photo A: This photo shows the first independent lab confirming that for the official test dummy (the 22-lb CRABI 12-Month-Old dummy), the middle slot is correct as it is below the shoulder line.  The technician is flipping up the upholstery to show how the higher slot is clearly NOT "at or below" the test dummy's shoulder.

The yellow arrow points to the highest shoulder harness slot - the lab ruled that the middle slot is correct instead of this top slot.

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Photo B: This photo shows a second independent test lab performing a fitment check, on the same regulated dummy.  This photo again confirms that the middle slot is correct, and shows how the top slot is grossly higher than proper (this lab performs fitment tests by cutting away the foam to expose the slots visibly, but leaves the foam under the dummy to represent an accurate seated position).

The yellow arrow points to the top shoulder harness slot – this lab also ruled that the middle slot is correct instead of this top slot.

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Photo C: As part of their recommendation that the middle slots are appropriate for a child sized like the CRABI 12 dummy, this photo shows the second independent lab evaluating the top slot as being above the dummy’s shoulders, in contradiction to our instructions.

The yellow arrow points to the highest shoulder harness slot, which is clearly NOT "at or below" the regulated test dummy's shoulder.

In addition to the lab confirmations above, our instructions are in line with recommendations from all leading safety groups and car seat technicians, including the one below: 

"Orbit instructions are very clear that the harness slots that are at or below the child’s shoulders should be used when restraining the rear-facing child in the Orbit seat.

"The photos that I viewed [Photos B and C above] showed two very different uses of the harness; one [Photo B] showed a harness coming from below the shoulders (correct position), and the other [Photo C] showed the harness clearly above the child’s shoulders (incorrect position). To be in compliance with manufacturer's instructions, the first [Photo B] is the correct orientation of harness location. Use of a harness that comes from above the shoulders [Photo C] is clearly a misuse and would be documented as such at a checkup event."

- Lorrie Walker, Training Manager and Technical Advisor, Safe Kids USA

As a responsible car seat manufacturer, we have designed our car seats to accommodate children both above and below average in size and seated torso height, which is why we have slot positions to accommodate a very wide range of body shapes.  The CRABI 12-Month-Old dummy is made to represent the average size of a one-year old child, and therefore has an "average" seated torso height that is shown above to be appropriate for the Orbit Infant Car Seat’s middle shoulder harness position.  (While the CRABI dummy is the maximum weight of 22 lbs, it does not represent the "biggest baby" in terms of seated torso height.)

We have provided additional informational links to car seat safety recommendations at the end of this article.

Crash testing: the consequences of shoulder harness position in dynamic lab testing

In the numerous and regular safety compliance tests we have performed on our production car seats at an independent test laboratory, we have never seen an Orbit Baby car seat fail a test.  Also, our Infant Car Seat is in compliance with all of the crash testing requirements of FMVSS 213 according to NHTSA’s own testing. Our crash tests, as well as NHTSA's, were all performed according to our shoulder harness instructions, and all passed. These results point to how important it is that product instructions are followed for lab testing, and that specifically the harness position is properly set.

Correct harness positioning has an especially large influence on crash testing results.  This is because safety testing is an extremely high-g, forceful event.  These tests represent quite severe auto accidents; the peak g-force load in a compliance test sled reaches up to 25 g's (while accelerometer readings on the dummy can reach upwards of 50 g's).  For context, astronauts aboard the Space Shuttle experience a maximum of 3 g's at launch.  Improperly securing the test dummy allows it to accelerate upwards in a significant way, resulting in unpredictable test conditions.

Orbit Baby is Committed to Real-World Safety

Nothing is more important to us at Orbit Baby than the safety and well-being of children.  While we believe all car seat companies prioritize safety, we believe that Orbit Baby uniquely prioritizes real-world safety.  We understand that even the most safely made products can be compromised if they are not used correctly, which is why we educate Orbit Baby customers on proper car seat usage.  We develop and patent technologies like our StrongArm™ mechanism, that allow everyone to more easily achieve a safe car seat installation. 

We believe that by providing more information to Orbit Baby parents, they will better understand the reasons behind important product instructions, and are therefore more likely to follow them in daily life.  Properly following product instructions is crucial to real-world car seat safety, and we emphasize that you should always refer back to your car seat’s manual.  Given that even experienced technicians can sometimes overlook importantinstructions, we cannot over-emphasize this aspect of car seat safety.

More information

(Ref1 ) http://www.car-safety.org/rearface.html: “[F]rontal and frontal offset crashes combine for about 72% of severe crashes.   Side impacts are about 24%.   Rear and rear offset crashes only account for about 4%. The NHTSA FARS database shows similar numbers.”

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