(57) A safety arrangement for vehicle doors (2) which are operated by a pressure medium,
which arrangement limits the risk of a person's becoming trapped in a bus door with
consequent risk of personal injury. The invention brings about a temporary reduction
in the air pressure in the door machinery (14). The pressure is reduced during the
door closing process and reverts to full pressure when the vehicle exceeds a certain
limit speed. This function reduces the risk of injury and makes it easier for someone
who becomes trapped, e.g. between door and bodywork while alighting, to free him/herself.
It is also possible for another passenger to push the door open and free the trapped
person.
The desired function is achieved by leading the pressure medium from the pressure
tanks (3) to the door machinery (14) via a pressure limiting value (10) at the time
of door opening and by thereafter allowing the air to flow through a different clear
passage (11,13), resulting in full pressure, when the doors have closed and the vehicle
has reached a certain speed.
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