Question Can someone please tell me all about over-rotation?

ADS

Aurezalia

Well-known member
Over-rotation is when the RF'ing seat is pressed downward towards the front of the car. I imagine it as sort of the opposite of cocooning.
As far as I know, the higher (55lb) RF'ing limits on Swedish seats is possible because of the foot prop to prevent rotation backwards. That's the only way I can think of off the top of my head to prevent over-rotation.
 

aeormsby

New member
The main danger I would think is that a child will 'ramp up' in an accident when RF (they will slide upward in the seat). And if they don't have adequate shell above their head they could come in contact with the seat in front of them.

Also, having a RF seat directly behind a seat (like in an outboard position) would limit the rotation also since the seat would only rotate until it came in contact with the front seat (unless there is so much space between the RF seat and front seat that it wouldn't).
 

Pixels

New member
The further down a seat rotates, the harder the harness has to work to keep the child in the seat. Less of the force is directed into the shell, and more into the harness.

A footprop or Australian tethering would reduce the rotation, as would bracing. Bracing can be a bit of a crapshoot, because the vehicle seats will move forward as well in a collision, and depending how much they move, the vehicle seat may not even be there to provide any support to the child restraint.
 

LISmama810

Admin - CPS Technician
Routing the seatbelt around the back of the seat (a la the Coccoro) would also reduce downward rotation.

If I had a Britax convertible I'd be tempted to Australian-tether it, to be honest. I'm more concerned with downward rotation than rebound. (Not that I'm losing a ton of sleep over either one, mind you.)

For the record, Australian tethering is when you bring the tether back up to the regular forward-facing tether point, as opposed to tethering toward the front of the car (Swedish).
 

safeinthecar

Moderator - CPS Technician
The further down a seat rotates, the harder the harness has to work to keep the child in the seat. Less of the force is directed into the shell, and more into the harness.

Also, as the seat dumps down toward the horizontal, the pull of the weight of the child's head can cause neck injuries.
 

Minnesota

CPST Instructor
Another way to prevent or minimize the possibility of over-rotation for older RF kids in convertible seats is to ensure that the seat is more upright than the 45 degree recline angle meant for newborns. Most manufacturers allow the convertible seat to be as upright as 30 degrees for older kids who have good head control.
 

MarathonMama

New member
Is it more of a concern for older RF kids? Heavier children/babies?

Are convertables vs infant seats more likely to over rotate?

Is it more likely to happen in certain conditions (ie higher speeds)?

Over rotation doesn't always happen does it? Or does it always partially happen (assuming frontal impact)?

How much does the front passenger/driver seat actually move in an impact? I know everything moves in the direction of impact, but if the seat is locked into position then it can only move so much, no?

I guess I'm also having a hard time visualizing how far a seat could rotate unless it actually lifted off the seat itself or the method of installation was either loose or stretched a lot.
 

Pixels

New member
No seat will over rotate if it's used properly. There is a limit on how much the seat is allowed to rotate in the crash test standard.

How much the front seat moves depends a lot on the vehicle. Some vehicles, it won't move much. Some vehicles, it can move a foot or two. Even if it's locked into position, it's not unusual for the locking mechanism to break.
 

MarathonMama

New member
No seat will over rotate if it's used properly. There is a limit on how much the seat is allowed to rotate in the crash test standard.

How much the front seat moves depends a lot on the vehicle. Some vehicles, it won't move much. Some vehicles, it can move a foot or two. Even if it's locked into position, it's not unusual for the locking mechanism to break.

Thank you so much!

Another question: how does bracing affect over rotation? Could it be beneficial for the front seat to stop/slow down the movement of the CR or could it be hazardous for a CR to slam into the front passenger seat (as far as advanced air bags or CR breakage go, etc)? Even if both the CR and the passenger seat do both move in an impact, is it possible that they move at different rates or that one moves and the other doesn't move as much?

Do seats that allow bracing (like Britax or Radians) allow it because they perform different in testing in regard to over rotation? Or is it from other factors?

Sheesh, if you've made it through all of these questions I'm impressed :thumbsup: and forever grateful :love:
 

Pixels

New member
Thank you so much!

Another question: how does bracing affect over rotation? Could it be beneficial for the front seat to stop/slow down the movement of the CR or could it be hazardous for a CR to slam into the front passenger seat (as far as advanced air bags or CR breakage go, etc)? Even if both the CR and the passenger seat do both move in an impact, is it possible that they move at different rates or that one moves and the other doesn't move as much?

Do seats that allow bracing (like Britax or Radians) allow it because they perform different in testing in regard to over rotation? Or is it from other factors?

Sheesh, if you've made it through all of these questions I'm impressed :thumbsup: and forever grateful :love:

I don't think we really know the answers to all of these questions, definitively. Britax and Radians allow bracing. Most other seats allow for light touching or at least positioning the seat so close that it probably doesn't matter that there was a millimeter before the crash. Evenflo infant seats require an inch and a half of clearance between the handle and the seat in front because of the interaction between the two.
 

Car-Seat.Org Facebook Group

Forum statistics

Threads
219,690
Messages
2,200,936
Members
13,435
Latest member
pcarter

You must read your carseat and vehicle owner’s manual and understand any relevant state laws. These are the rules you must follow to restrain your children safely. All opinions at Car-Seat.Org are those of the individual author for informational purposes only, and do not necessarily reflect any policy or position of Carseat Media LLC. Car-Seat.Org makes no representations as to accuracy, completeness, currentness, suitability, or validity of any information on this site and will not be liable for any errors, omissions, or delays in this information or any losses, injuries, or damages arising from its display or use. All information is provided on an as-is basis. If you are unsure about information provided to you, please visit a local certified technician. Before posting or using our website you must read and agree to our TERMS.

Graco is a Proud Sponsor of Car-Seat.Org! Britax is a Proud Sponsor of Car-Seat.Org! Nuna Baby is a Proud Sponsor of Car-Seat.Org!

Please  Support Car-Seat.Org  with your purchases of infant, convertible, combination and boosters seats from our premier sponsors above.
Shop travel systems, strollers and baby gear from Britax, Chicco, Clek, Combi, Evenflo, First Years, Graco, Maxi-Cosi, Nuna, Safety 1st, Diono & more! ©2001-2022 Carseat Media LLC

Top