Page 77 - TBIS_15194-2019_(EN)_3nd
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TBIS 15194:2019
4.3.8.6 Front fork – Bending fatigue test plus rearward impact test
4.3.8.6.1 Requirement
When tested by the method described in 4.3.8.6.2, there shall be no fractures in any
part of the fork, and the permanent deformation, measured as the displacement of
the axis of the wheel-axle or simulated axle in relation to the axis of the fork steerer,
shall not exceed 45 mm.
For composite forks, the running displacement (peak-to-peak value) at the points
where the test forces are applied shall not increase by more than 20 % of the initial
values(Suspension-forks shall not increase by more than 40 % of the initial
values. )(see 4.3.1.6).
4.3.8.6.2 Test method
Mount the fork according to Annex G as shown in Figure 28.
4.3.8.6.2.1 Stage 1 Front fork – Bending fatigue test
Apply cycles of fully-reversed, dynamic forces of F6 in the plane of the wheel and
perpendicular to the fork steerer tube to a loading attachment and swivel on an axle
located in the axle-slots of the blades for 120 000 test cycles. The forces are given in
Table 20. The maximum test frequency shall be maintained as specified in 4.3.1.5.
Conclude the test if the running displacement (peak-to-peak value) at the point
where the test forces are applied increases by more than 20 % for rigid forks or more
than 40 % for suspension forks from the initial values.
Stop the test after 120 000 cycles and inspect the sample carefully for fractures. If
fractures are found, conclude the test.
If the sample completes 120 000 cycles without exceeding the displacement limits
noted above, and if no fractures or can be observed, perform the impact resistance
test described in 4.3.8.5 (The drop heights are given in Table 18). When the striker
has come to rest on the roller, measure the permanent deformation under the roller
and inspect the sample carefully for fractures.
4.3.8.6.2.2 Stage 2 Front fork – Bending fatigue test
With the same mounted as in 4.3.8.6.2.1. Apply cycles of fully reversed, dynamic
forces for 100 000 test cycles. The forces are given in Table 20.
If the sample completes 100000 cycles bending fatigue test without exceeding the
displacement limits noted above, and if no fractures can be observed, perform the
impact resistance test described in 4.3.8.5 (the drop heights are given in Table 18).
When the striker has come to rest on the roller, measure the permanent deformation
under the roller and inspect the sample carefully for fractures.
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