| 摘要 |
MEANS FOR SECURING ELASTOMERIC SHEATHING TO A ROOF SUR FACE A pair of plates are interposed between the head of a screw means fastened through a roof covering and into a roof surface and truss therebelow. One plate is a lock nut composed of ratchet toothed means fixed to and facing downwards of the screw head and the second plate is a disc-shaped member fixed to the sheath of the roof covering and has ratchet teeth facing upwards and engageable with the teeth of the screw lock nut member when the screw is mated with the disc-shaped member.
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