Abstract: An improved hold-down clamp (14) is disclosed for fastening a non-metallic grate (10), preferably formed of fiberglass, to a structural member (12). The clamp (14) includes a restraining clip (20) which prevents spreading of adjacent beams of the grate, and a hold-down clamp (46) which bears on the inner portion of the base of each beam. A threaded fastener (50) urges the hold-down clamp (46) toward the structural member (12), thereby forcing the bases of the beams into engagement with the structural member to clamp the grate to the structural member.

Abstract: An interlock grate structure is provided which includes longitudinal load bearing span bars having lateral locating holes spaced therealong for receiving transverse tie bars, the transverse tie bars having axial locking means which engage the longitudinal span bars at the point of juncture to prevent axial displacement of the tie bar relative to the span bar. A longitudinal lock rod serves to interlock the position of the transverse tie bar locking means with respect to the longitudinal span bar.

Abstract: There is provided a roll-type door having horizontally positioned slats which is normally held by operator means in an open position against gravity. Said operator means includes fusible means responding to a predetermined heat level for releasing said door and permitting same to move under gravity in a closing direction. Said operator means includes a device for initiating said door movement immediately after the response of said fusible means to said heat level and further includes a connection to braking means for insuring against too rapid a descent by the door. The door may be manually opened if desired or mechanical means, power driven if desired, may be provided for opening or assisting in opening such door. In the latter case, clutch means are provided for disconnecting same immediately upon breakdown of said fusible means whereby said door will be enabled to close freely in response to gravity subject only to control by the above-mentioned braking means.