In transport vehicles such as buses which are used for transporting people, many of the window structures therein comprise single panes which are secured in window frames. It is a requirement, however, that some of these window structures provide an evacuation passage for the passengers when in an emergency situation and therefore the window pane must be secured in a frame structure which will cause the pane to release itself from the frame by applying pressure against the pane. Such window structures are also commonly provided in ships where the pane cannot be opened to prevent water from infiltrating into the cabins but may be released by applying an outward pressure on the pane under emergency situations. A major disadvantage of such window structures is that they do not make it readily apparent that the window pane can be removed by applying pressure thereon from inside the vehicle. Also, the securing structure of the panes may not always cause the pane to be released by pressure due to malfunctions usually resulting from rust formation or the infiltration of foreign matter into the release mechanism. Another disadvantage of such window panes is that they cannot be forced out by children nor do children have the intelligence of realizing, particularly under a crisis situation, that a window pane can be opened by applying pressure thereon.
There is also a need to provide, in combination with such panes, a window lock which is easy and obvious to operate in order to open a window pane quickly under a crisis situation. There is also a need to provide a reliable window pane opening technique which is easy to assemble and to operate and which provides through-passage without destruction to the window pane or any part of the window frame structure.
A major inconvenience with offset sliding window panes provided on moving vehicles is that they cause friction noise with air flow when the vehicle is in motion. They also accumulate debris in the outer exposed track and cavities due to a vacuum effect caused by the air turbulence. The dirt infiltration also affects the sliding displacement of the panes in their respective track and cause wear of the nylon glide bushings. They also accumulate road salt deposits in winter months which lead to corrosion. This also makes it more difficult to remove the panes for cleaning.
Further when a single pane breaks it is often necessary to remove the frame to effectuate the glass pane replacement.