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4.8.6 Frame — Fatigue test with a vertical force

When tested by the method described in TBIS 4210-6:2017, 4.5, there shall be no visible cracks or
fractures in the frame and there shall be no separation of any parts of the suspension system.

For composite frames, the running displacement (peak-to-peak value) at the point where the test forces
are applied shall not increase by more than 20 % of the initial value (see TBIS 4210-3:2016, 4.6).

Conduct the test in two stages on the same assembly.

4.8.7 Folding mechanism - special requirements

For the frames with folding mechanisms, the folding mechanisms should conform to the requirements of
Sec. 4.8.1~4.8.6; besides, it is necessary to measure the opening force and the closing force of the folding
mechanisms before and after the test (if the opening force and the closing force are adjustable, the
opening force and the closing force should be adjusted to the maximal value); the opening force and the
closing force should not be lower than 90% before test, and should not be stuck; in addition, the rotation
shaft of the folding mechanisms should not be loose because a gap appearing in the shaft.

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