| 摘要 |
Grating comprises two sets of mutually parallel, interlocking fibreglass reinforced moulded resin bars extending transversely to one another. One set are underlying bearing bars of rectangular cross-section having a thickness T and a height H. Each bar has inverted U-shaped notches of depth D at longitudinally spaced positions. Each notch includes oppositely directed oblique slots extending downwards and outwards terminating adjacent the upper edge of a bar in oblique cam surfaces diverging outwards and upwards spaced apart a distance W". The second set of bars are of inverted U cross-section including a horizontal base portion and a pair of diverging legs of thickness equal to that of the diver-ging slots in the bearing bars but having a vertical height H' greater than the vertical depth D fo the notches. The cross bars have flat horizontal upper edges and oblique edges diverging outwards. The bars have rectangular locking notches of width W' equal to the thickness T fo the bearing bar but of height H' less than their overall vertical height H". The locking notches form laterally opposed vertical edges which contact the opposite sides of the bearing bars, their horizontal edges being spaced a distance W" between the upper edges of the opposed oblique camming surfaces in the bearing bars. When the cross bars are forced into the inverted U-shaped notches of the bearing bars, their locking notches are deflected inwards by the camming action of the camming surfaces at the upper ends of the oblique slots and momentarily deform the cross bar legs so that they enter the slots. Consequently the cross bars join to the bearing bars with their oblique legs snapping flush with the oblique surfaces of the latter and prevent removal.
|
