BC Transit – Air Brake Course

Identifying Primary and Secondary Systems (continued)
On a long wheel base vehicle such as a semi-trailer or other larger
commercial vehicle, a bus for instance, there is no such transfer of
weight onto the front axle. During braking, even heavy braking, the
weight of the vehicle remains over the drive axles and the trailer axles
(if equipped.) Therefore, the majority of braking effort is
concentrated at the rear axle or axles. …next slide...
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