Page 39 - TBIS_15194-2019_(EN)_3nd
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TBIS 15194:2019
4.3.5.9.5.3 Test machine
The test machine shall incorporate a system that drives the wheel under test by tyre
contact and a means of measuring the braking-force, and typical examples of two
types of machine are illustrated in Figure 6 and Figure 7.
Figure 6 shows a machine in which a roller drives the individual wheels, and Figure 7
shows a machine in which a driven belt contacts both wheels. Other types of
machine are permitted, provided they meet the specific requirements listed below
and those specified in 4.3.5.9.5.4 and 4.3.5.9.5.5.
The specific requirements are as follows:
a) the linear surface velocity of the tyre shall be 12,5 km/h and shall be controlled
within ± 5 %;
b) a means of laterally restraining the wheel under test shall be provided which does
not influence the measurement of braking force;
c) a means of laterally applying forces to the brake-levers at the point specified in
Figure 4 — shall be provided, with the width of the contact on the lever not greater
than 5 mm. In the case of back-pedal brake, a means of applying forces to a pedal
is also required.
4.3.5.9.5.4 Instrumentation
The test machine shall be instrumented to include the following:
a) a device to record the surface velocity of the tyre, accurate to within ± 2 %;
b) a device to record the braking force (see Figures 14 and 15, for example),
accurate to within ± 5 %;
c) a device to record the operating force applied to the hand-lever or pedal,
accurate to within ± 1 %;
d) a water spray system, to provide wetting of the brakes of the bicycle, consisting
of a water reservoir connected by tubing to a pair of nozzles arranged as shown
in Figure 8. Each nozzle shall provide a flow of water at ambient temperature of
not less than 4 ml/s. The wheel shall be suitably enclosed to ensure that, in
addition to the rim, any hub-or disc-brake is thoroughly wetted before a test
begins;
e) a system for loading the wheels of the bicycle against the driving mechanism (see
4.3.5.9.5.5).
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