Slide-plate drop head and grid shoring systems

A universal prop system for a grid shoring system for building construction, comprising:

• a plurality of interchangeable prop stands;
• a plurality of interchangeable stringer jacks;
• a plurality of interchangeable slide-plate drop heads, each slide-plate drop head for removably interconnecting a selected one of the interchangeable prop stands with a selected one of the interchangeable stringer jacks, each slide-plate drop head further comprising a drop seat defining a bottom rail interface to removably support a bottom rail of the grid shoring system;
• wherein each drop seat is selectively movable between an upper drop seat position and a lower drop seat position to move the bottom rail between an upper bottom rail position and a lower bottom rail position;
• and
• a variety of stringer jacks, each stringer jack comprising a threaded rod, a threaded collar movably captured on the threaded rod, and a stringer head connected to the threaded rod to support a top rail of the grid shoring system;
• wherein each stringer jack telescopically interconnects with a selected slide-plate drop head to selectively move the stringer head with respect to the selected slide-plate drop head between an upper stringer head position and a lower stringer head position in response to rotation of the threaded collar to move the top rail between an upper top rail position and a lower top rail position;
• wherein each slide-plate drop head comprises a slide plate, a rail interface extending in a release direction, and an impact interface positioned to receive a strike from a hammer with sufficient force to drive the slide plate in the release direction to release the drop seat to fall from the upper position to the lower position.