A braking system for a cab of a boarding bridge configured for accessing aircraft and ships, the boarding bridge comprising a round structure to which the cab is rotatably attached, the braking system having braking means configured to halt rotation of the cab, and also having an operating sensor, wherein the braking means are activated by the operating sensor when the operating sensor detects a failure of the drive system of the cab,
- the braking means comprising a cab rotation blocking mechanism comprising a linearly movable lance which is attached to a frame that supports the round structure, and further comprising a coupling part, shaped to engage the lance and that is integral to and rotates with the cab;
- wherein the lance is aligned with the coupling part, and wherein the breaking means further comprise retention means, the retention means being capable of keeping said lance in an inactive position separated from the coupling part, and wherein the breaking means further comprise pushing means, the pushing means being capable of propelling said lance toward the active position in which said lance fits into the coupling part and thereby engages the coupling part and blocks rotation of the cab;
- wherein the retention means is released when the operating sensor detects a failure of the cab drive system, so as to allow the lance to be propelled to its active position by the pushing means.