Special Test Equipment
3.1 The loading bar, used in 5.1 and 5.2, shall be a rigid cylinder
with an outside diameter of 152 mm (6 inches) that has hemispherical ends
with radii of 76 mm (3 inches) and with a surface roughness that does
not exceed 1.6 mm (63 micro-inches) root mean square.
3.l.1 The length of the loading bar shall be 100 mm (4 inches) less
than the width of the seat back in each test.
3.1.2 The stroking mechanism applies force through a pivot attachment
at the centre point of the loading bar which allows the loading bar to
rotate in a horizontal plane 30 degrees in either direction from the transverse
position.
3.1.3 A vertical or lateral force of 17 793 N (4,000 pounds) applied
externally through the pivot attachment point of the loading bar at any
position reached during a test specified herein, shall not deflect that
point more than 25.4 mm (1 inch).
3.2 The head form used for the measurement of acceleration shall be
a rigid surface comprised of two hemispherical shapes, with total equivalent
weight of 51 N (11.5 pounds). The first of the two hemispherical shapes
shall have a diameter of 165 mm (6.5 inches). The second of the two hemispherical
shapes shall have a diameter of 50.8 mm (2 inches) and shall be centred
as shown in Figure 1 to protrude from the outer surface of the first hemispherical
shape. The surface roughness of the hemispherical shapes shall not exceed
1.6 mm (63 micro-inches) root mean square.
3.2.1 The direction of travel of the head form shall be coincidental
with the straight line connecting the centre points of the two spherical
outer surfaces which constitute the head form shape.
3.2.2 The head form shall be instrumented with an acceleration sensing
device whose output is recorded in a data channel that conforms to the
requirements for a 1000 Hz channel class as specified in SAE Recommended
Practice J2lla (December 1971). The head form shall not exhibit resonant
frequency below three times the frequency of the channel class. The axis
of the acceleration sensing device coincides with the straight line connecting
the centre points of the two hemispherical outer surfaces which constitute
the head form shape.
3.2.3 The head form shall be guided by a stroking device so that the
direction of travel of the head form is not affected by impact with the
surface being tested at the levels called for in the standard.
3.3 The knee form for measurement of force shall be a rigid 76 mm
(3 inch) diameter cylinder with an equivalent weight of 44.5 N (10 pounds)
that has one rigid hemispherical end with a 38 mm (1.5 inch) radius forming
the contact surface of the knee form. The hemispherical surface roughness
shall not exceed 1.6 mm (63 micro-inches) root mean square.
3.3.1 The direction of travel of the knee form shall be coincidental
with the centreline of the rigid cylinder.
3.3.2 The knee form shall be instrumented with an acceleration sensing
device whose output is recorded in a data channel that conforms to the
requirements of a 600 Hz channel class as specified in the SAE Recommended
Practice J2lla (December 1971). The knee form shall not exhibit resonant
frequency below three times the frequency of the channel class. The axis
of the acceleration sensing device shall be aligned to measure acceleration
along the centreline of the cylindrical knee form.
3.3.3 The knee form shall be guided by a stroking device so that the
direction of travel of the knee form is not affected by impact with the
surface being tested at the levels called for herein.
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