Simpson SEAT BELT - Manual (Page 2)

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Version 1
Figure 1: Shoulder and Lap Belt Mounting Zones – Upright Seating Position
The Lap Belts should be mounted off the center of the drivers’ hip at an angle of 45 to 65 degrees down from the
horizontal. (see Figure 1) All seat belt mounts need to be as close to the seat system as possible. In some
cases, it is advantageous to mount the belts inside the seat. The lap belts should be mounted with a double
shear type mount and the lap anchor should be allowed to rotate freely.
It is advantageous to have the Pull Up style adjuster on the lap belt inside the seat, just on top of the leg radius.
Custom size anchors can be ordered to facilitate this. In some cases, this may not be a viable option because of
driver size. If this is the case, the adjuster must be mounted outside the seat with a short pull up mount.
The path that the lap belt takes from the anchor to the buckle must be free of obstruction. If the belt routes
through a seat opening, it must allow for the belt to rotate forward by at least 30 degrees without being cut or
frayed.
The lap belt mount needs to have a secure anchor to the chassis or frame of the vehicle. The mount should be
capable of withstanding a 3500 lb shock load.
Lap Belt Mounting for a Reclined Seating Position ( Less than 65 Degrees of back angle ) For Lap Belt
mounts in a reclined seating position it is necessary to change the lap belt mounting zone to 0 degrees, vertical,
+/- 10 degrees. This is because of the lower angle of the pelvis. The belt should route over the flats on your
pelvis on both sides.
The Shoulder Belts should be mounted at an angle of 0 to 20 degrees down from the top of the shoulder.(see
Figure 1) The shoulder belts need to be mounted as close to the driver as possible. They may also angle
( +10 / -10 deg )