Fitting seats and seatbelts to a van requires design to meet the loading requirements in a frontal collision. The LVV Standards for seats and for seatbelt anchorages set out the different ways of meeting these requirements.

In the Hiace shown, some second-hand seats were to be fitted, [...]]]>

Van seatbelts - view from side

Fitting seats and seatbelts to a van requires design to meet the loading requirements in a frontal collision. The LVV Standards for seats and for seatbelt anchorages set out the different ways of meeting these requirements.

In the Hiace shown, some second-hand seats were to be fitted, these had the seatbelt anchorages in the seat frames, making them “Stressed Seats”. This is much neater than having all the seatbelts going to the floor, however it means that the seat has to be strong enough to take the seatbelt loads.

Van seatbelts - view from rear

A quick stress calculation showed that the back beams were not strong enough, and had to be strengthened by adding a 50 x 25 box beam to the original 50 x 50 box beam to make a 50 x 75 box beam.

The mounting system is the “Over-floor mounting bar” system, as in the LVV Standard.

Also visible are headrest mounts on the rear seat back, because of the closeness of the rear window.

Installation by owners Eastern Rentals 66 TeRakau Drive 09 577 0128
Design calculations and LVV Certifification by John Brett Technology Ltd. 0800 LOW VOLUME (0800 569865)

The LVV Standards are here- Seats and seat anchorages [692kB PDF] and here Seatbelts [1024kB PDF]

REAR FACING SEATS
Rear facing seats have to restrain occupants from frontal impact. This means that the seat backs have to be far stronger than normal, or a supporting structure provided.
This is a matter which is often overlooked by some commercial modifiers.

The requirements from ADR VSb 5B are:
Appendix B
Rear-Facing Seat Strength

Rear-facing seats and their anchorages must comply with the requirements of the latest edition of ADR 3/…
In addition, a rear-facing seat should withstand, without imposing any load on any other seat in the vehicle, a load equivalent to twenty times the weight of the seat and its occupants applied in the forward direction relative to the vehicle. Seats intended to accommodate more than one occupant should withstand the loads applied by all occupants simultaneously. This requirement should be demonstrated with the occupant load uniformly distributed over the backrest and head restraint of the seat.
The occupant mass to be used to determine the test loads for each category of seat must be:
Category 1 – 68 kgs
Category 2 – 38 kgs
Category 3 – 26 kgs.

Reasearch link:-
[DOC]
COMMERCIAL MANUFACTURE AND INSTALLATION OF ADDITIONAL SEATS
– 8:15am
File Format: Microsoft Word – View as HTML
Rear-Facing Seat Strength. Rear-facing seats and their anchorages must comply with the requirements of the latest edition of ADR 3/. …
www.infrastructure.gov.au/roads/vehicle…/bulletin/…/vsb_05_b.doc