What does the tether IDEALLY do in a frontal crash?

B

broxbourneDELETE

Guest
If anyone has a video link so I can see how the tether is supposed to perform, this will probably clear up my questions about the physics of a crash and the tether's impact.

If this does not exist, could someone please answer:
(1) What does the tether ideally do in a crash? What is its primary function?
(2) What other things does it do in a crash that may help?
(3) What things can you do wrong with a tether that is worse than not tethering at all? (If answering this question, please go into detail ... thanks)

I've read lots of opinions on the prescribed tautness ("not too") of the tether and the necessity of the tether ("pretty good without but better with") and centeredness ("better centered but a little off okay") and its preferred winding path (too varied to put into words).

(I have two children in a Britax WZ and BV, both rear facing. The WZ will need to turn FF pretty soon though.)

Thanks everyone!
 
ADS

SPJ&E

New member
(1) What does the tether ideally do in a crash? What is its primary function?
It improves the stability of the seat and doesn't allow the carseat to rebound up into the seatback. It is especially beneficial in side-impacts and rollovers, where there's more force and more chance of the seat moving all over the place and is great for older/heaver rear-facing children. Go to this page and at the bottom there are crash test videos of a tethered RF seat to give you an idea of what happens: http://www.cpsafety.com/articles/stayrearfacing.aspx

I don't know about the other 2 questions, but I'm sure someone else will be very helpful!
 

wendytthomas

Admin - CPST Instructor
Staff member
If anyone has a video link so I can see how the tether is supposed to perform, this will probably clear up my questions about the physics of a crash and the tether's impact.

If this does not exist, could someone please answer:
(1) What does the tether ideally do in a crash? What is its primary function?
(2) What other things does it do in a crash that may help?
(3) What things can you do wrong with a tether that is worse than not tethering at all? (If answering this question, please go into detail ... thanks)

I've read lots of opinions on the prescribed tautness ("not too") of the tether and the necessity of the tether ("pretty good without but better with") and centeredness ("better centered but a little off okay") and its preferred winding path (too varied to put into words).

(I have two children in a Britax WZ and BV, both rear facing. The WZ will need to turn FF pretty soon though.)

Thanks everyone!

Well, RFing the tether helps secure the seat so that it doesn't rebound. Britax doesn't like it seats rebounding for some reason. They want their seats to be one with the car.

FFing a tether reduces head excursion. While Britax and Sunshine Kids are the only two companies that produce seats that can be tethered RFing, all seats can be, and should be, tethered FFing. Without the tether the seat must not allow the head excursion to go more than 32" (how far from the seat back the head goes in a collision). With the tether it cannot go more than 28".

As far as I know that's the only thing it does in a crash.

Things you can do worse than not tethering... Well, not tethering is not the end of the world, all seats are designed to perform without a tether. Things you could do wrong. Tether it improperly so that it fails in a crash (tethering it to a moving part of the car, the steering wheel, gear shift, something wrong). FFing you could tether it to the cargo hooks by mistake in an SUV and have it tear up the cargo hook and throw it about the cabin like a projectile. If you don't tether put it away so that it doesn't go thrashing about.

Others may think of other things, I'm sure.

Wendy
 

SafeDad

CPSDarren - Admin
Staff member
If anyone has a video link so I can see how the tether is supposed to perform, this will probably clear up my questions about the physics of a crash and the tether's impact.

If this does not exist, could someone please answer:
(1) What does the tether ideally do in a crash? What is its primary function?
(2) What other things does it do in a crash that may help?
(3) What things can you do wrong with a tether that is worse than not tethering at all? (If answering this question, please go into detail ... thanks)

I've read lots of opinions on the prescribed tautness ("not too") of the tether and the necessity of the tether ("pretty good without but better with") and centeredness ("better centered but a little off okay") and its preferred winding path (too varied to put into words).

(I have two children in a Britax WZ and BV, both rear facing. The WZ will need to turn FF pretty soon though.)

Thanks everyone!


At the simplest level, Both a rear-facing and front-facing tether act the same for the top of a carseat as the seatbelt [or lower attachments] that are used to secure the bottom of the seat. It couples the child restraint to the vehicle seat. That lets the restraint take best advantage of the crushing vehicle frame in a crash to increase the time a passenger has to ride down the crash forces.

The less coupling, the more movement you will have during the crash. That movement will eventually come to a more abrubt (i.e. more forces applied to the occupant) stop, if the stop happens after the vehicle frame has absorbed all the energy it can.
 
B

broxbourneDELETE

Guest
At the simplest level, Both a rear-facing and front-facing tether act the same for the top of a carseat as the seatbelt [or lower attachments] that are used to secure the bottom of the seat. It couples the child restraint to the vehicle seat. That lets the restraint take best advantage of the crushing vehicle frame in a crash to increase the time a passenger has to ride down the crash forces.

The less coupling, the more movement you will have during the crash. That movement will eventually come to a more abrubt (i.e. more forces applied to the occupant) stop, if the stop happens after the vehicle frame has absorbed all the energy it can.

Ok that makes sense. So actually the tether ought to be pretty darn taut to the point that is starts to change the seat angle. Is that right?
 

SafeDad

CPSDarren - Admin
Staff member
Ok that makes sense. So actually the tether ought to be pretty darn taut to the point that is starts to change the seat angle. Is that right?


There should be no slack in the tether. It doesn't need to be so tight that you are using a lot of strength to tighten it or such that it is gouging the fabric at the top of the seat.
 

Car-Seat.Org Facebook Group

Forum statistics

Threads
219,656
Messages
2,196,898
Members
13,530
Latest member
onehitko860

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